Human and natural causes of marine turtle nest and hatchling mortality and their relationship to hatchling production on an important Florida nesting beach

[From the U.S. Government Printing Office, www.gpo.gov]

Florida Game and Fresh Water Fish Commission
Nongame Wildlife Program

Technical Report No. 1

Human and Natural Causes of Marine Turtle Nest
and Hatchling Mortality and Their Relationship to
Hatchling Production on an Important Florida
� .5 Nesting Beach

COASTAL ZONE
INFORMATION CENTER

j13 Ij

QL
666
.EC536 April 1987
1987
I

Human and Natural Causes of Marine Turtle Nest and
Hatchling Mortality and Their Relationship to Hatchling
Production on an Important Florida Nesting Beach

L. M. Ehrhart and B. E. Witherington

Project Director: L. M. Ehrhart

Research Assistant: B. E. Witherington

Florida Game and Fresh Water Fish Commission
Nongame Wildlife Program
Technical Report No. 1
April 1987

U.S. DEPARTMENT OF COMMERCE NOAA
COASTAL SERVICES CEN1 ER
2234 SOUTH HOPSON AVENJUE
CHARLESTON, SC: T29.5 "- 3

Submitted as

Final Report
S-- As- mProject Number GFC-84-018
cm ~ 12 June 1986

"roperty of CSC Librezay

ABSTRACT
Project Number: GFC-84-018
Project Title: "Human and natural causes of marine turtle nest and
hatchling mortality and their relationship to hatchling production on an
important Florida nesting beach.."

Date of final report: 12 June 1986
Project Director: L.M. Ehrhart

Populations of Western Atlantic loggerheads ICaretta caretta) and
Florida Green turtles (Chelonia mydas) have been in historical decline.
The identification and protection of beaches that are major producers of
loggerhead and green turtle hatchlings are vital to the preservation of
these species.
A study assessing loggerhead and green turtle hatchling production
was initiated at a 21 km stretch of beach in south Brevard County,
Florida (Melbourne Beach) during the 1985 nesting season. Nesting
densities were assessed from a season-long (10 May - 12 September)
census, in which every nest was counted and identified to species. An
analysis of average reproduction success was made from 100 loggerhead and
27 green turtle sample nests. Daily tallies of specific disturbances to
nests aided in formulating dimensional descriptions of factors which
caused clutch and hatchling mortality.

An unprecedented 10,240 loggerhead and 281 green turtle nests were
counted within the Melbourne Beach study area in 1985. Approximately 48
and 51 percent of the constituent eggs of loggerhead and green turtle
nests resulted in hatchlings that successfully entered the surf. These
values are very high compared to data from other nesting beaches.

A severe September northeaster storm was the major cause of
mortality for clutches of both species. Raccoon predation and the
disorientation of hatchlings by beachfront lighting were also significant
in limiting reproductive success. Beachfront lighting was also found to
significantly deter green turtles from nesting. Predation of nests by
raccoons was limited to a small portion of the study area. The rate of
hatchling disorientation was found to decrease following the enforcement
of a regional ordinance restricting beachfront lights.

Management recommendations include: bestowing a special protective
status for the Melbourne Beach area; providing efforts to monitor and
regulate beach and nearshore activities; initiating specific management
practices to mitigate mortality; and enhancing research and public
education efforts regarding Melbourne Beach's marine turtles.

~~0 12,28qQ2%~ ~ ~ ~

ACKNOWLEDGEMENTS

The financial support for this research was provided by a contract

with the Nongame Wildlife Program of the Florida Game & Fresh Water

Fish Commission. We acknowledge that support with sincere thanks and

also thank the staff members of the program with whom we worked: Jim

Cox, Brad Gruver and David Cook. They maintained a cooperative,

business-like relationship throughout the course of the contract. We

work continuously with the professional cooperation of Major Robert

Patterson and his staff at the Titusville headquarters of the Florida

Marine Patrol. Also, the dispatchers and south Brevard deputies of the

Brevard County Sheriff's Department are always courteous and helpful.

We thank both law enforcement agencies.

Once again this year the Board of County Commissioners of Brevard

County generously provided a special permit for use of three-wheel

motorcycles on the beach. We thank them for the privilege.

A number of students provided competent assistance in the field.

From UCF these include Carol Glaros, Thom Schmid, Lawrence Leupschen

and Jo Miranda; from elsewhere, Jeanette Wyneken (University of

Illinois @ Urbana-Champaign), Elaine Christens (Queens University,

Ontario), Kazuo Horikoshi (University of Florida), and Mendi Raymond

(University of South Florida).

At IUCF a number of persons in the Division of Sponsored Research

deserve our thanks for their help with contractual matters and word

processing. They include Joan Burr, Rusty Okoniewski, Betsy Swayne and

Bonnie Coller.

iii

We thank the Indian River Audubon Society for its continuous

support of our work in south Brevard County. Also we are grateful to

Capt. Perry Smith and his staff at Sebastian Inlet State Recreation

Area and the management of Holiday Haven Mobile Home Park, who tolerate

our seemingly bizarre activities. Stewart Marcus, of Hobe Sound

National Wildlife Refuge, provided useful, but otherwise unavailable,

comparative data and Dr. Haven C. Sweet, of UCF, provided hardware,

software and sound advice for the computer analysis. We thank theme

all.

A special note of thanks goes to Paul W. Raymond of the National

Marine Fisheries Services (NOAA) in St. Petersburg. He helped in the

field when he could and was instrumental in the creation of our

computer graphics. More importantly, however, as the one who single-

handedly began the work at Melbourne Beach four years ago, he continues

to be the philosophical and practical conscience for the continuing

work on that beach.I

TABLE OF CONTENTS

ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . iii

LIST OF TABLES . . . . . . . . . . . . . . . . . . vii

LIST OF FIGURES . . . . . . . . . . .... .. ix

I. INTRODUCTION . ..... . . . . . ...........

II. METHODS . .. .. .. .. .. .. .. .. .. .. .. .7

Study Area . . . . . . . . . . . . . . . . .... 7
Nesting Census .. . . . . . . . .. 9
Marking Sample Nests. . . .. . . . . . . 10
Assessment of Sample Nest Success...... . 13
Daily Qualitative and Quantitative Observations. . . 17
Assimilation of Data Incidental to Nightly Excursions 18
Statistical Analysis ................. 18

III. RESULTS ... . . . . . . . . . . . . . . ....... 19

Nesting Census ........ 19
Analysis of Initial Sample Nest Data ......... 27
Incubation Period .. .... 32
Analysis of Reproductive Success . ..38
Measures of Success . .... 38
Factors Affecting Reproductive Success of
Sample Nests . . . . .43
Analysis of Daily Qualitative and Quantitative
Observations . . . . . .......57
Mortality Influenced by Numbers of
Nesting Females . . . . . . . ......57
Ghost Crab Predation . . . . . . . . .. 58
Raccoon Predation . . . . . . ..... 58
Minor Forms of Predation . . . . . . . 62
Mortality Attributable to Humans . . . ...... 65
Post-Emergence Hatchling Mortality . . . ..... 66
Hazards to Nesting Females . . ....67
Analysis of Hatchling Production . .....71
Analysis of Data Incidental to Nightly Excursions . . 74

IV. DISCUSSION . . . . . . . ... . 76
Nesting Densities'and'Distributions . . . . . . . 76
Turtle Size, Clutch Size and Incubation Period . . . . 81
Information on Movements of Nesting Females . . . .. 85

Reproductive Success and Productivity . . . . . . .86
Measures and Comparisons . . . . ........86
Factors Affecting Reproductive Success .. ....90
Mortality Influenced by Numbers of
Nesting Females . . . . . . . . . ........90
Damage Related to Sand Accretion and Surf ...91
Damage Due to Storms ...............92
Raccoon Predation . . . . 06. . . . . . . . .93
Ghost Crab Predation. .............. 94
Damage from Plant Roots . ......... . . . 96
Human Induced Mortality . . . . . . . . . . . ..96
Offshore Predation ................99I
The Importance of Melbourne Beach as a Marine
Turtle Rookery . . . . . . . . . . . . . . . . . 100

V. MANAGEMENT RECOMMENDATIONS . . . . . . . . . . . . . . . 101

VI. SUMMARY . . . . .* . . . . . . . . . . * 104
APPENDIX . . . . .. ......................106

L ITERATURE CITED . .. ........ . . . . . . . . . . . . . 132

LIST OF TABLES

1. Nesting and non-nesting emergences of loggerheads and
green turtles counted within the Melbourne Beach study
area in 1985 . . . . . . . . . . . . . . ..26

2. A table of Wilcoxon Rank-Sum Test results for comparing
measurements of loggerhead and green turtle nests/nesting
females .... . . . . . . . . . . . . . . . . ....... 30

3. Tested correlations between measured variables of logger-
head nests/nesting females . . . . . ... . . . ...... 31

4. Tested correlations between measured variables of green
turtle nests/nesting females.. ............... 34

5. A table of Kruskal-Wallis one-way ANOVA results for comparing
loggerhead clutch incubation periods from three zones of
deposition ......................... 37

6. Emergence success of loggerhead and green turtle sample nests
marked at Melbourne Beach in 1985 . . . . ..40

7a. Tables of Kruskal-Wallis one-way ANOVA results for comparing
emerging success of loggerhead sample nests from three zones
of deposition . . . . . . . . .... 41

7b. Tables of Wilcoxon Rank-Sum Test results for comparing
emerging success of loggerhead sample nests from three
zones of deposition ....... .............. 42

8. Descriptive fates of loggerhead sample clutches marked at
Melbourne Beach in 1985 ................... 44

9. Descriptive fates of eggs from loggerhead sample nests marked
at Melbourne Beach in 1985 . . . . . . . . .. .. . . . . . . 45

10. Descriptive fates of green turtle (Chelonia mydas) sample
clutches marked at Melbourne Beach in 1985 ......... 46

11. Descriptive fates of eggs from green turtle sample nests
marked at Melbourne Beach in 1985 . . . . ..47

12. Summary of deformities in nest-trapped hatchlings and
embryos from loggerhead and green turtle sample nests . . . . 55

vii

13. Occurrences of ghost crab burrows in randomly chosen
beach plots . . . . . . . . . ................5

14. Hlatchling disorientations within the Melbourne Beach
study area in 1985 . . . . . . . . . . . . .. ....... 69

LIST OF FIGURES

1. The 2I km Melbourne Beach study area in 1985 . . . . . . . . 8

2. Melbourne Beach study area beach profile showing
three arbitrarily delineated zones . . . . . . . . . . . . 16

3. Temporal distribution of loggerhead (Caretta caretta)
nesting within the Melbourne Beach study area in 1985 . . . 20

4. Temporal distribution of green turtle (Chelonia mydas)
nesting within the Melbourne Beach study area in 1985 . . . 21

5. Horizontal nesting distribution of loggerheads (Caretta
caretta) within the Melbourne Beach study area in 1985 . . . 24

6. Horizontal nesting distribution of green turtles
(Chelonia mydas) within the Melbourne Beach study
area in 1985 ........................ 25

7. Horizontal distribution of loggerhead (Caretta
caretta) non-nesting emergences in 1985 . . . . . . . . . . 28

8. Relationship between loggerhead (Caretta caretta)
clutch size and nesting female size . . . . . . . . . . . . 33

9. Relationship between green turtle (Chelonia
mydas) clutch size and nesting female size . . . . . . . . . 35

10. Clutch fates of loggerhead (Caretta caretta)
sample nests marked within the MelbTourne Beach
study area in 1985 .............................. 48

11. Fates of constituent eggs from loggerhead (Caretta
caretta) sample nests marked within the Melbourne
Beach study area in 1985 . . . . . . . . . . ..... ... 49

12. Clutch fates of green turtle (Chelonia mydas) sample
nests marked within the Melbourne Beach ytu
area in 1985 . . . . . . . . . . . . . . . . . . . . . . . 50

13. Fates of constituent eggs from green turtle (Chelonia
mydas) sample nests marked within the Melbourne Beach
study area in 1985 . . . . . . . . . . . . . . . . . . . . . 51

14. Marine turtle clutches depredated during specific
milestones of incubation . . . . . . . . . . . . . . . . . . 61

15. The relationship between the temporal distributions
of loggerhead nesting and raccoon predation on
Melbourne Beach in 1985 . . . . . . . . .63

16. The spatial distribution of raccoon predation compared
with the spatial distribution of raccoon road-kills . . . . 64

17. The spatial distribution of hatchling disorientation
at Melbourne Beach in 19 85 ................. 68
18. The temporal distribution of hatchling disorientation
at Melbourne Beach in 1985 ................ 70

INTRODUCTION

Florida's beaches serve as regular nesting locations for three

species of marine turtles. Of these three, the Atlantic loggerhead

(Caretta caretta caretta) is the most abundant. Though rare by compari-

son, a significant number of animals from the remnant population of

Florida green turtles (Chelonia mydas mydas) also nest in Florida.

Atlantic leatherbacks (Dermochelys coriacea coriacea) nest sparsely in

Florida, which constitutes the northern extent of their nesting range

(Pritchard, 1979).

All these marine turtles are believed to be in serious worldwide

decline (Ross, 1982; King 1982). The loggerhead (threatened), the green

turtle (endangered) and the leatherback (endangered) are all protected

under the terms of the Endangered Species Act of 1973. In Florida,

historical glimpses of nesting marine turtle abundance exist only as

anecdotes (Audubon, 1926). These accounts frequently lack assured

species identifications and make the past relative abundances of species

rather enigmatic. There is, however, nothing in the literature that

contradicts the belief that past population densities were much higher

than present ones.

Historically, the principal cause of the decline of marine turtle

populations has been unregulated harvest at all life history stages, egg

to adult. Though protected from exploitation in the U.S., these animals

face other direct threats. The explosive proliferation of human

development along Florida's coast may be the most severe of these. The

presence of beach degrading structures constricts present nesting areas

and is likely to severely limit the number of beaches suitable for3

nesting in the future (Coston-Celments and Hoss, 1983).

Beaches where significant numbers of marine turtles still nest are

vital sources of recruitment for these waning populations. To identify

major areas of marine turtle nesting in the U.S., Hopkins and RichardsonI

(1984) reviewed aerial and ground reconnaissance data from several

sources. The resulting compendium suggested that a stretch of beach

from Melbourne Beach to Sebastian Inlet in South Brevard County,3

Florida, supported the largest aggregation of nesting loggerheads in the

U.S. Separate aerial surveys of Florida (the most densely nested state

by far) reinforce these findings (Carr and Carr, 1977; Murphy and

Hopkins, 1984).

In 1981, Ehrhart and Raymond (1983) initiated a systematic, season-

long survey of nesting activity on a stretch of beach at Indialantic and

Melbourne Beach, Florida. High loggerhead nesting densities were found,I

with a disproportionate increase in nesting densities in the southern

sections of the study area (near Melbourne Beach). The study area was

extended southward in 1982 to include the area from Melbourne Beach to3

Sebastian Inlet. Estimates of loggerhead nesting at this 21 km beach

were calculated to be 9,432 and 7,753 clutches in 1983 and 1984 (Ehrhart

and Raymond, ins.). These estimates correspond to an unprecedented 450

and 370 nests per kilometer. Information on loggerheads nesting else-

where in the Western Atlantic suggests that the density of females that

nest on this South Brevard beach is unsurpassed in this hemisphere

(Ross, 1982). Ross recognized that the population that nests in the3

Southeastern U.S. is second in size only to that which breeds at

Masirah, an island off the Oman coast in the Indian Ocean. This Indian

Ocean population may or may not have a different subspecific identity

(Caretta caretta gigas; Pritchard, 1979).

The term "Florida green turtle" is not a taxonomic distinction but

will be used henceforth to identify those turtles which nest almost

exclusively in Florida. These animals may be remnants of a larger

population whose nesting grounds were disjunct from other Atlantic

populations. The only significant nesting of Florida green turtles

occurs on the central-southeast coast of Florida (Dodd, 1981). Even

within this restricted area, very few stretches of beach are reported to

host an excess of one nest per kilometer (Hopkins and Richardson, 1984).

Florida green turtle nesting densities on the South Brevard beach (21km)

were found to average approximately 2.2 and 1.6 nests per kilometer in

1983 and 1984 (Ehrhart and Raymond, ms.).

Marine turtles are recognized nonconformers to the prescribed r-K

selection continuum (Ehrhart, 1982). While adults display a relatively

horizontal survivorship curve, eggs and hatchlings suffer tremendous

losses during these short life history stages. The reproductive stra-

tegy of marine turtles is to anticipate these huge losses with a pro-

fusion of eggs and resultant hatchlings. This strategy dictates laying

large clutches of eggs multiple times over several nesting seasons. It

is currently uncertain what losses eggs/hatchlings can incur and still

provide stasis-maintaining recruitment (Richardson, 1982).

Very few accurate assessments of natural hatchling recruitment from

marine turtle nesting beaches exist in the literature. Most accounts of

"hatchling production" or "hatch rates" refer to artificial hatchery

operations (Richardson, 1978; Andre and West, 1981; Bustard, 1972) or

experimentally manipulated clutches of eggs (Bustard, 1971; McGehee,

1979; Ackerman, 1980). Other studies involve naturally deposited nests

in situ, though concentrate primarily on elucidating rates of major

predation (Gallagher, 1972; Davis and Whiting, 1977; Anderson, 1981;

Hill and Green, 1971) and seldom quantify mortality beyond major distur-

bances to nests. Some studies exist that identify both conspicuous and

subtle mortality factors (Mortimer, 1981; Schulz, 1975; Carr and Hirth,

1962; Ragotzkie, 1959; Balazs, 1980; Bjorndal et al., 1985), but concen-

trate primarily on comparisons of reproductive success between similarly

sampled nests on the same beach or the establishment of baseline repro-

ductive success for undisturbed nests. Such studies typically sample

only from nests exhibiting hatchling emergences, nests from limited

areas or limited numbers of nests, rendering the extrapolation of nest

reproductive success to beach productivity refutable. Studies that

present relatively unbiased assessments of marine turtle reproductive

success applicable to nesting beach hatchling production exist only for

South Carolina loggerhead nesting beaches (Hopkins et al., 1978; Cald-

well, 1959a) and the Tortuguero, Costa Rica green turtle nesting colony

(Fowler, 1979).

Although estimates of nesting beach productivity are rare, approxi-

mations of maximum productivity may be made using frequently reported

rates of nest predation, assuming that nests not depredated display

predictable success. By far, the most significant predator of marine

turtle nests in the U.S. is the raccoon (Procyon lotor). Estimates of

damage caused by raccoon predation range from 40 to 100% nest destruc-

tion for Cape Sable, Florida (Davis and Whiting, 1977); Hutchinson

island, Florida (Worth and Smith, 1976) and South Carolina beaches

(Stancyk et al., 1980). At the major nesting beach at Cape Canaveral,

Florida, as many as 90% of the natural nests are destroyed within 24

hours of deposition (Ehrhart, 1976). The estimates given for these

areas represent nests totally destroyed and not overall mortality which

may be much higher. These high rates of raccoon predation contrast with

those surmised for the South Brevard nesting beach. Raccoon predation

was judged superficially by Bjorndal et al. (1983) to be quite low,

based on nightly turtle tagging efforts. They further speculated that

because of this, the South Brevard nesting beach may produce more

hatchling loggerheads than any other Florida beach.

South Brevard's current lack of high density development and

vehicular beach traffic may also contribute to high reproductive suc-

cess. This attribute is quickly waning, however, given the currently

phenomenal rate of coastal development there. This condition warrants a

* ~~~rapid analysis of man's influence on the nesting beach while actions

taken to curtail his effects are still possible.

The Recovery Plan for Marine Turtles (Hopkins and Richardson, 1984)

stresses the necessity of monitoring levels of hatchling production,

especially on densely nested beaches. Given the apparent importance of

the South Brevard nesting beach, a study systematically quantifying its

reproductive output was proposed. The primary objective of this study

was to determine overall hatchling production for this beach by assess-

ing the number and fate of the clutches deposited there. An additional

objective was to identify factors which were significant causes of egg

and hatchling mortality. A further objective was to suggest means by
which those various biotic and abiotic factors could be mitigated.

There exists an implied potential for the production of over one million

hatchling turtles per season from this South Brevard beach. This study

sought to assess the extent to which this vast reproductive potential is3

actually realized.

METHODS

I ~~~Study Area

The area of study was a previously delineated 21 km stretch of

beach in south Brevard County, Florida (Figure 1), henceforth referred

to as Melbourne Beach. The northern study area boundary was an arbi-

trary zero point, located exactly 5 km south of 5th Avenue in India-

l~antic, Florida. Sebastian Inlet State Recreation Area served as the

opposing boundary, 21 km to the south. The study area was divided into

I ~~~21, one kilometer sections which were identified by numbered stakes and

permanent landmarks. Each of these one-kilometer areas will be referred

to as sections, with section I beginning at the zero point and sections

2 through 21 extending southward. Unless otherwise stated, all research

activities took place within these prescribed boundaries.

Melbourne Beach's physical attributes include a relatively sloped

5 ~~~berm, coarsely grained sands often consisting of broken shell, a surf

that breaks in close proximity to the beach, and most other general

traits that characterize high energy beaches (Bascom, 1960). During the

1985 marine turtle nesting season, the profile of Melbourne Beach

I ~~~retained the effects of a severe storm that occurred in November of

1984. Evidence of erosion remained in the form of a steeply scarped

foredune. By the beginning of the 1985 nesting season, sea rocket

3 ~~~(Cakile edentula) had begun to pioneer the bare substrate at the base of

I ~~~~~~~~~~~~~~~~7

INDIALANTIC

MELBOURNE
BEACH
80� 30' W

28� N

\0 21

SEBASTIAN
Go I INLET

Figure 1. The 21 km Melbourne Beach study' area in 1985. The shaded
regions are areas of denser residential development.
Numbered sections are one kilometer in length. The
northernmost section (1) begins five kilometers south of
5th Avenue in Indialantic, Florida.

1 ~~~~~~~~~~~~~~~9

the foredune. Later in the summer, this area became sporadically sodded

as precarious clumps of sea oats (Uniola paniculata) fell from the

crests of the sandy cliffs and runners of beach morning-glory (Ipomoea
pes-caprae) crept out onto the berm. By mid-summer, the base of the

dune in certain sections had become sparsely vegetated, but the formid-

able dune escarpment continued to preclude any marine turtle nesting in

the heavily vegetated portion of the dune.

The vast majority of beachfront properties along Melbourne Beach

are privately owned. Four centers of residential development are

indicated by Figure 1. This development consists primarily of single-

family dwellings with scattered single or two-story motels. Multi-story

condominiums exist mainly in the northernmost sections of the study

area, though two rather large projects exist in sections 11 and 15, and

additional buildings are currently under construction in sections 9, 12,

and 15. No major "armoring" of the dune (seawalls, revetments) is

currently present at Melbourne Beach. Even in areas where substantial

residential development exists, the dune has been left relatively intact

and some dune vegetation remains. Other areas, up to one kilometer in

length, remain undeveloped, and the dune is naturally vegetated with saw

palmetto (Seranoa repens).
Nesting Census

For an uncompromised assessment of marine turtle nesting within the

21 km study area, exhaustive daily surveys were conducted. These daily

nesting surveys were initiated 13 May and continued until 12 September,

1985. Because of favorable beach conditions on 13 May, an additional

10 May survey and an 8 May aerial survey, an accurate assessment of

nesting could be made from 8 to 12 May. This addition completed an

unbroken interval spanning 8 May to 12 September, 1985.

Very little nesting was missed due to the 8 May starting date.3

This conclusion was based on interviews with beachfront residents and

the first observation of hatchling emergence evidence, which placed the

date of first significant nesting at 4-6 May. Nesting surveys were

discontinued when two consecutive days of zero nesting were observed.I

Each day's nesting survey was accomplished by traversing the 21 km

study area by means of small, three-wheeled motorcycles. The survey was

begun each day at about 0545 hrs, just after the cessation of most3

turtle nesting activity and before the resulting sign could be obscured.

The numbers of nesting and non-nesting emergences for each I km section

were recorded for each species. Characteristics of the tracks and nest

sites were used to differentiate nesting and non-nesting emergences, and

to make species identifications. Differences in gait and nesting

behaviors which determine track and nest sign evidence are described by

Bustard (1972).I

Marking Sample Nests

To assess clutch and hatchling mortality, a representative sample

of nests deposited within the study area were marked and followed3

throughout their incubation. A sampling method was employed that

assured proper representation of the overall distribution of nesting

within the study area. On randomly chosen nights, one to three investi-

gators patrolled the study area on three-wheeled motorcycles. Starting

points (north, middle, and south access sites) and starting directions

(north or south) were chosen randomly prior to the beginning of each

night's field work. Only nests of turtles encountered during the early5

stages of nesting behavior (emergence from surf, constructing the body

pit or digging the egg chamber) were marked as sample nests. Turtles

U ~~~encountered during latter stages (oviposition, covering, returning) were

generally ignored because of the difficulty in counting eggs already in

the egg chamber. This method of sampling eliminated spatial and tem-

3 ~~~poral bias in sample nest selection.

With a few exceptions noted below, clutches were counted and nests

were marked at the time of deposition according to the following proto-

* ~~~col.

1. Clutch size was determined by counting eggs as they fell into the

egg chamber. Investigators caught each egg instantaneously with

one hand and then let it pass into the egg chamber as it was

I ~~~~recorded on a digital counter in the other hand.

2. The species of turtle, nest identification number, date and time of

deposition, activity of the animal at discovery, and approximate

location (to the nearest 0.1 kmn) were recorded.

3. For the purpose of relocating the clutch, the exact location of

each egg chamber was determined by making a precise measurement to

* ~~~~a numbered stake at the dune base and to any permanent landmarks.

A 20 cm diameter aluminum disc was buried 0.5 in to the south of

each nest to facilitate relocation (by the use of a metal detector)

in the event that the stake was removed.

1 ~~~4. A monel metal tag was applied to the proximal trailing edge of the

left front flipper on each turtle. These tags were provided by Dr.

Archie Carr of the University of Florida and had a University of

3 ~~~~Florida return address engraved on them.

5. Using a graduated forestry caliper (straight line measurements) and

a graduated metal tape (over curvature measurements), (standard)

straight line and greatest (total) carapace length, straight line3

carapace width, curved carapace length and width, and maximum head

width (Pritchard et al., 1983) were measured and recorded for each

turtle. Indications of carapace and flipper injury and evidence of

previous tags (calluses, tearouts) were also noted.

6. Each nest's position on the beach was measured in relation to

nearness to vegetation, spring high tide mark, and dune escarpment

base. Ghost crab burrows and obstructions in the egg chamber,I

height of the dune scarp and type of nearest vegetation were also

noted.

A total of 100 loggerhead and 27 green turtle nests were marked and3

included in the sample. In order to obtain numbers of green turtle

nests adequate for analysis, it was necessary to mark and use some

without the benefit of observing the nesting female. In these cases,3

clutch size was determined by carefully excavating with nest within

12 hours of deposition. At that time, the eggs were counted and

returned to their original positions within the egg chamber. Success

among nests treated in this fashion was found not to differ from thoseI

nests whose clutches were counted during deposition. Green turtle

sample nests, although most often chosen in a fashion dictated by the

sampling protocol, were otherwise chosen randomly from nests discovered3

during the daily nesting surveys.

Two leatherback nests were marked as samples within the study area

boundaries, although as noted for some green turtle nests, the adult

female was not seen in either case. An additional leatherback nest was

discovered about 1 km north of the study area and dangerously near the

surf. It was relocated within the study area for convenience of obser-

vation.

Assessment of Sample Nest Success

As part of the clutch and hatchling survivorship assessment, all

sample nests were observed each day during the nesting surveys for signs

of depredation or other disturbances. Notes describing disturbances to

sample nests were recorded in a daily log. When sample nests exhibited

signs of a hatchling emergence, the sand immediately surrounding the

emergence was smoothed, so that subsequent emergences could be dis-

cerned. Hatchling emergence sign was, in many cases, partially effaced

by wind, rain, or tide. In those cases where hatchling tracks could be

distinguished, the number of hatchlings leaving the nest was estimated.

Tracks of predators, drag marks, evidence of hatchling disorientation,

and dead or dying hatchlings in the vicinity of the emergence were

noted.

When sample nests no longer displayed any sign of emergence acti-

vity, or at 60 days post-deposition, nests were excavated and their

contents inventoried. From the exhumed nest contents, the following

were determined: (1) The number of successfully hatched eggs; (2) the

number and condition of live and dead hatchlings remaining in the nest;

(3) the number and condition of hatchlings that had pipped the egg but

had not successfully emerged from the shell; (4) the number, and onto-

logical and physical condition of unhatched embryos; (5) the number of

apparently infertile eggs and those for which no judgment about fertil-

ity could be made; and (6) evidence of subterranean perturbation or

predation and the number of eggs affected.

To determine the modus operandi of subterranean ghost crab preda-

tion, several unmarked nests which displayed signs of obvious ghost crab

damage (eggshells in the spoil of an accompanying crab burrow) were3

excavated. Samples of obviously deprediated eggs were collected and

cataloged, so that comparisons could be made with suspect eggs discov-

ered in sample nests.

Four different measures of reproductive success were formulated to3

describe aspects of survivorship and productivity. Three of the mea-

sures of success are based on the fraction of eggs/hatchlings that

attain certain developmental milestones. These milestones bound the3

period of marine turtle life history that begins with deposition as eggs

and ends with submergence in the surf as hatchlings. These three

measures of success (hatching success, emerging success, and approximate3

ocean-bound success) were calculated for each sample nest where such a

determination was possible. An additional measure of success, emergence

success (not to be confused with emerging success), was not calculated

for each sample nest, but was instead, a single value based on allI

sample nests.

Definitions of the aforementioned measures of success are as

follows.3

Hatching success - The fraction of eggs which result in hatchlings

that successfully extricate themselves from the eggshell, calculated as

a percentage of yolked eggs within each clutch.

Emerging success - The fraction of eggs which result in hatchlings

that successfully escape from the nest (i.e., reach the surface of the

sand), calculated as a percentage of yolked eggs within each clutch.

Approximate ocean-bound success - The fraction of eggs which result

in hatchlings that successfully enter the ocean, calculated as a per-

I ~~~centage of yolked eggs within each clutch. This measure is termed an

approximation, because it is based largely on circumstantial evidence of

hatchling mortality en route from nest to surf.

3 ~~~~Emergence success - The fraction of sample nests that result in at

least some emergent hatchlings, calculated as a percentage of total

sample nests for each species.

A number of important characteristics were recorded for each sample

nest. The following is a list of characteristic definitions.

Deposition date - The date the clutch was deposited by the female

turtle.

I ~~~~Incubation period - The period of time, beginning with the deposi-

tion date and ending with the date of the largest hatchling emergence.

For clutches that had only small hatchling emergences, the period ended

with the first hatchling emergence. When clutches emerged during

daylight hours (most often following afternoon rainshowers), the final

day of incubation was counted as one-half day.

3 ~~~~Zone of deposition -The region of beach where a sample nest was

deposited by the female turtle (Figure 2). Three arbitrary zones, each

with boundaries parallel to the surf line, were established as conven-

ient descriptive localities: zone A, within 2 m of the dune escarpment

I ~~~base; zone B, between the boundary of zone A and I m above the spring

high-tide mark; zone C, below the lower boundary of zone B.

Disturbance - Any perturbation to the nest which causes mortality

3 ~~~of eggs or hatchlings.

Figure 2. Melbourne Beach study area beach profile showing three arbitrarily
delineated zones of deposition; A, B and C. Zone A lies within
2 m of the dune escarpment base; zone B lies between the
boundary of zone A and I m above the spring high tide mark; and
zone C lies seaward of the lower boundary of zone B.

IDUNE
1ESCARPMENT

I I I

ATLANTIC OCEAN
al

* ~~~~~~~~~~~~~~~17

Daily Qualitative and Quantitative Observations

A daily log of events was maintained throughout the 1985 nesting

I ~~~season. Detailed notes on meteorological conditions such as tides,

precipitation, temperatures (air and surf) and surf and beach conditions

were kept, in addition to notes on significant or unusual events per-

3 ~~~taining to the nesting beach.

In addition to the sample nest assessment, a survey of the inci-

dence of raccoon predation was carried out each day. During daily

nesting surveys, the location, type, and extent of any deprediated nests

were noted in a daily log. Each incidence of raccoon predation was

described using evidence within the nest (eggshells, embryos and other

egg contents). These descriptions indicated whether the incident

I ~~~involved fresh nests (nests less than 24 hours old), nests in early

incubation (containing eggs not near pipping), nests in late incubation

or pre-emergence (containing term embryos or hatchlings), or post-

emergence nests (containing only shells from emergent hatchlings).

Observations were limited to days which offered favorable beach condi-

tions for accurate sign interpretation.

As a relative measure of raccoon population density, the locations

N ~~~of all raccoon road kills occurring on Highway AIA were recorded from

10 May to 12 September, 1985. Highway AlA parallels the nesting beach

study area on the west at a distance of approximately 100-150 meters.

3 ~~~~Hatchling disorientation due to beachfront lighting was hypothe-

sized to be a significant cause of post-emergence mortality. For this

reason, an extensive survey of hatchling disorientation was undertaken.

3 ~~~During daily nesting surveys, every observable hatchling emergence trace

was tallied in a daily log. These emergences were described as being

properly oriented or disoriented. Disorientations were further noted as

being major (involving the majority of the clutch) or minor (involving

the minority).

To supplement information gathered from sample nests on post-

emergence hatchling loss, 48 non-disoriented and 18 disoriented clutches

were examined for ghost crab predation. Assessments of post-emergence

mortality were based on a combination of sign evidence (drag marks and

dead hatchlings) and ghost crab burrow excavation.

Assimilation of Data Incidental to Nightly Excursions

During nightly excursions to mark sample nests, many turtles whose

nests were not marked were encountered. These turtles were consistently

checked for previous tags and tag scars. As often as possible, measure-

ments were obtained on those turtles previously tagged, so that data

concerning growth, nesting interval, and interim travel could be

acquired.

Statistical Analysis

Comparisons and correlations between data were made using primarily3

nonparametric statistical tests (Ott, 1984). Although no test for

normality was attempted, the distribution of most data (especially

reproductive success data) did not approximate a normal curve. Small3

sub-sample sizes made the application of statistical tests invalid in

very few cases. Individual statistical tests are mentioned where

appropriate in the results section of this report.

RESULTS

Nesting Census

The first survey of nesting activity within the study area was

conducted on 8 May. By this date, it was apparent that some loggerhead

nesting had already occurred. Initial nesting of loggerheads on Mel-

1 ~~~bourne Beach in 1985 was believed to have occurred between 4 and 6 May.

This conclusion was based, in part, on interviews with beachfront

residents. The first recorded loggerhead hatchling emergence, observed

30 June, reinforced this conclusion, assuming a 55-57 day incubation

I ~~~period (a range encompassing values recorded for early season clutches).

Loggerhead nesting continued until 12 September, after which nesting was

considered insignificant. One loggerhead nest was observed as late as

3 October. Loggerhead nesting occurred exclusively during the hours of

darkness, except for two reported afternoon nestings. These afternoon

nestings each occurred during daily high-tide periods. Initial green

3 ~~~turtle nesting occurred on 31 May and continued until 10 September.

Commiencement of nesting varied by one month between loggerheads and

green turtles (figures 3 and 4). These different dates of initial

nesting manifested a distinct difference between the two species in the

I ~~~time of the season at which the heaviest concentration of nests were

active. The greatest concentration of loggerhead nests were incubating

on 22 July (63%), while for green turtles, the greatest portion of nests

3 ~~~were incubating on 19 August (75%).

NO. LOGGERHEAD
NESTS
220
200
180
160= !

14130 140 150 0 10 0 10 200 21 220 230 240 250

MAY J UJE |JULY AUXT UAN TEEN0IR

JULIAN DATE/MONTH

Figure 3. Temporal distribution of loggerhead (Caretta caretta) nesting
within the Melbourne Beach study area in 1985.

m - m -

NO. GREEN TURTLE
NESTS
12
10

1 i 2 240 0 260
130 140 150 160 170 180 190 200 210 220 230 240 250 260
MAY JUNE I JULY AUGUST SEPTEMBER

JULIAN DATE/MONTH

Figure 4. Temporal distribution of green turtle (Chelonia mydas) nesting
within the Melbourne Beach study area in--Il57'

Temporal nesting distributions of loggerheads (Figure 3) and green

turtles (Figure 4) indicate that nesting in both species reaches a

plateau rather than a single peak of activity. Overlapping cycles of

various periodicities may or may not be present in these nesting distri-

butions. The considerable daily variation in nesting numbers, with some

exceptions, did not correspond with changes in any measured variable.

These daily oscellations did not appear synchronous between species.

Sharp fluctuations in surf temperature are known to influence nesting

activity (Williams-Walls et al., 1983); however, no such fluctuations of

sufficient amplitude to affect nesting occurred off Melbourne Beach in

1985. Tropical Storm Bob passed the study area briefly on 24 July and

did cause a temporary drop in loggerhead nesting activity, probably due

to rough surf conditions (Figure 3).

The total census of nesting activity within the study area revealed

10,240 loggerhead, 281 green turtle, and two leatherback clutches depos-

ited in 1985. These counts of loggerhead and green turtle nests exceed

all estimates from previous surveys on this same stretch of beach
(Ehrhart and Raymond, ms.). Average loggerhead nesting density within

the study area was 490 nests per kilometer.

The number of green turtle nests recorded within the study area in

1985 surpassed estimates from previous seasons by over five-fold. Green

turtle nesting densities averaged 13.4 nests per kilometer and were as

high as 30 nests per kilometer within some parts of the study area in3

1985.

Leatherback nesting within the study area was minor. Because

leatherbacks are known to nest in April on Florida Beaches (Fletemeyer,

1984), some nesting may have gone unobserved because surveys were not

* ~~~~~~~~~~~~~23

begun until 8 May. One leatherback nest, in addition to the two discov-

ered within the study area, was deposited just beyond the northern

boundary. The dates of these three leatherback nestings were 14 May,

11 June, and 20 June.

Figure 5 depicts loggerhead nesting by I km sections. Northern and

southern sections of the study area displayed consistently lower nesting

densities compared to central sections. No definite correlation could

be made between this spatial nesting distribution and any measured or

observed 'attribute of the beach. Loggerhead nesting densities by

section ranged from 209 to 666 nests per kilometer (Table 1).

Figure 6 represents green turtle nesting by section. Areas of

nesting preference differed greatly between loggerheads and green

turtles. The greatest densities of green turtle nesting occurred in the

southern sections of the study area. General attributes of these

southern sections included sparser development, less nightly human

activity, and less beachfront lighting than the northern sections. As a

general observation, lighted areas of the beach were typically devoid of

green turtle nesting, while darker areas, especially areas shrouded by

trees, enjoyed extensive green turtle nesting. Green turtle nesting

densities within the study area ranged from 3 to 30 nests per kilometer

(Table 1).

Crawls from female turtles that advanced beyond the recent high

tide mark but did not result in a successful nesting were considered

non-nesting emergences. Table I lists numbers of non-nesting emergences

for each species by section. Forty-four percent of all loggerhead

emergences and 31 percent of all green turtle emergences resulted in

abandoned attempts. This difference was found to be significant (bino-

Figure 5. Horizontal nesting distribution of loggerheads (Caretta caretta)
within the Melbourne Beach study area in 1985. Section one is
located five kilometers south of 5th Avenue in Indialantic,
NO. NESTS Florida.
700-

1 3 5 7 9 11 13 1 17 19 2
600 7

300-

1 3 5 7 9 11 13 15 17 19 21
LOCATION (one km sections)

Figure 6. Horizontal nesting distribution of green turtles (Chelonia mydas)
within the Melbourne Beach study area in 1985. Section one is
located five kilometers south of 5th Avenue in Indialantic,
Florida.
NO. NESTS
35-

30 -

/ /
/ / Zr

1 3 5 7 9 11 13 15 17 19 21
LOCATION (one km sections)

TABLE 1

Nesting and non-nesting emergences of loggerheads (Caretta caretta) and
green turtles (Chelonia mydas) counted during a census of 21 km of beach
in south Brevard Co., Florida, 1985. Locations are specified as one km
sections, the northernmost section (1) beginning five km south of 5th
Avenue, Indialantic, Florida.

Loggerhead Emergences Green Turtle Emergences

Location Nesting Non-nesting Nesting Non-nesting

1 292 178 4 3
2 424 371 7 6
3 467 378 14 4
4 440 398 7 0
5 454 407 8 6
6 599 582 11 9
7 506 495 7 5
8 469 573 3 0
9 504 639 8 3
10 607 591 18 6
11 629 428 6 3
12 666 458 12 4
13 532 413 5 2
14 633 311 12 6
15 554 289 23 11
16 661 369 18 6
17 510 268 21 10
18 468 215 29 8
19 306 194 16 9
20 310 184 30 19
21 209 130 22 12

Total 10,240 7,871 281 124

* ~~~~~~~~~~~~~27

mial two-population test, P K0.05). Loggerhead non-nesting emergences

are depicted by section in Figure 7. Loggerheads emerging in the

northern sections of the study area appeared to abandon nesting attempts

more frequently than loggerheads emerging farther south.

Analysis of Initial Sample Nest Data

Appendix tables I and 2 contain respectively, measured morphologi-

cal characteristics of loggerheads and green turtles encountered during

this study. Turtles whose nests were incorporated as sample nests are

included with their identifying sample nest numbers. Means, standard

deviations, and ranges are included for all morphological characters.

Some turtles listed in these tables were encountered twice within the

nesting season; in these cases, only initial measurements were used in

calculating means. One green turtle with a grotesquely malformed

(kyphotic) carapace was also excluded from these calculations.

Sample nests were categorized as having been deposited within three

3 ~~~specified zones, A, B, and C (Figure 2). Due to a sharply scarped dune

profile caused by a severe storm in November of 1984, nesting was, for

the most part, restricted to an area seaward of the primary dune face.

Despite this restriction, distinct variation in vertical nest site

choice was observed, both within and between species (Appendix tables 3

and 4). On the average, green turtles nested higher on the beach than

did loggerheads. The majority of loggerheads nested within zone B,

* ~~~while most green turtles nested within zone A. The mean distance

measured from clutch to dune base was 6.8 m (SD = 4.6 m, n = 100) for

loggerhead and 1.9 m (SD = 2.5 m, n = 27) for green turtle sample nests.

3 ~~~A student's t-test revealed significant differences between these means

(P < 0.05). Variations in these vertical distributions of loggerhead

Figure 7. Horizontal distribution of loggerhead (Caretta caretta)
non-nesting emergences in 1985, expressed as a percentage
of total emergences. Section one is located five
100 - kilometers south of 5th Avenue in Indialantic, Florida.

90-

80 -

70 -

50 0-

10-

0
1 3 5 7 9 11 13 15 17 19 21
LOCATION (one km sections)

* ~~~~~~~~~~~~~29

and green turtle nests did not appear to correspond to cycles of spring

and neap tides. Likewise, there was no apparent trend toward higher

nest placement later in the season. There was, however, some relation-

ship apparent between daily tide conditions and loggerhead nest place-

ment. Based on subjective observations, loggerheads emerging during

daily high-tide periods deposited clutches closer to the dune than those

emerging during low tide.

Clutch sizes for loggerhead and green turtle sample nests are

listed in Appendix tables S and 6. One green turtle clutch was excluded

from the mean. The turtle that deposited this clutch was frightened by

the bright lights of an onlooker and appeared to have aborted midway

through oviposition without attempting to cover her clutch. Three

leatherback clutches contained a mean of 94 yolked eggs (SD = 7.0) and

26 yolkless eggs (SD = 9.4). Mean clutch size for loggerheads was found

to be 116 eggs. Seven clutches of green turtle eggs were excavated and

given to Ross Witham (Florida DNR) for incorporation into a head-

starting program. With the inclusion of these clutches, mean green

turtle clutch size was 145 eggs (SD = 21.7, n = 33). Clutch sizes of

* ~~green turtles and loggerheads were found to differ significantly

(Table 2).

Loggerhead clutch size was found to be negatively correlated with

advancing dates of deposition (Table 3). No significant correlation was

found, however, between green turtle clutch size and date of deposition

(Table 4).

Mean straight line carapace length (CLSL) measurements differed

significantly between loggerheads and green turtles (Table 2). The

TABLE 2

A table of Wilcoxon Rank-sum Test results for comparing measurements of
loggerhead (Caretta caretta) and green turtle (Chelonia mydas)
nests/nesting females sampled from 21 km of beach in south Brevard
Co., Florida, 1985. Abbreviations: IP, incubation period; CLSL,
carapace length straight line of nesting female; ES, emerging success of
clutch; CS, clutch size; DFD, distance the clutch was deposited from the
dune escarpment base.

LOGGERHEAD GREEN TURTLE Significance
Measurement N x Mean Rank N i Mean Rank One-tailed(P)

IP* 67 53.1 da 42.3 20 54.0 da 49.7 NS
CLSL 119 92.2 cm 50.1 27 101.5 cm 100.6 <0.0001
ES 97 55.7 % 61.8 25 56.6 % 60.5 NS
ES* 85 63.6 % 54.1 24 58.8 % 48.7 NS
CS 100 116.2 51.9 33 144.7 99.8 <0.0001
DFD 118 6.8 m 83.1 27 1.9 m 28.8 <0.0001

*only measurements from nests not affected by a September storm tested

TABLE 3

A table of correlations between sets of variables tested by Spearman's
Rank Order Correlation Coefficient (Rsp). The data source is a group of
loggerhead (Caretta caretta) nests/nesting females sampled from 21 km of
beach in south Brevard Co., Florida, 1985. Abbreviations: CLSL,
carapace length straight line of nesting female; IP, incubation period;
ES, emerging success of clutch; DD, date clutch was deposited; DO, date
female observed nesting; CS, clutch size.

Variables Tested n Pairs Rsp Significance
One-tailed (P)

CLSL/CS 97 0.71 <0.0001
CLSL/DO 97 -0.23 0.013
CLSL/ES 97 0.10 NS
CLSL/ES* 83 -0.02 NS
IP/CS* 67 0.17 NS
IP/DD* 67 -0.37 0.0015
IP/ES* 67 -0.05 NS
ES/CS 97 0.12 NS
ES/CS* 83 0.05 NS
ES/DD 97 -0.28 0.004
ES/DD* 83 0.02 NS
CS/DD 97 -0.37 <0.0002

*only variables from nests not affected by a September storm tested.

finding that nesting loggerheads were, on the average, smaller than

Florida green turtles agreed with the conclusions of Ehrhart (1979).

A significant positive correlation was found between body size ofI

nesting loggerheads (CLSL) and their respective clutch sizes (Table 3,

Figure 8). Ehrhart (1979) observed a similar relationship between body

size and clutch size of nesting loggerheads.

A significant negative correlation was found between the CLSL of

nesting loggerheads and the Julian date on which they were observed

nesting (Table 3). These findings indicate that larger loggerheads were

nesting earlier in the season than smaller ones. This condition prob-

ably explains the observed diminution in clutch size with advancing date

of deposition.

As for loggerheads, a significant positive correlation was foundI

between green turtle CLSL and clutch size (Table 4, Figure 9), but no

correlation was detected between CLSL and nesting dates of females

(Table 4).

Incubation Period

The determination of incubation period relied upon favorable beach

conditions and could not be made accurately for all sample clutches.

The conclusion of incubation was marked by the first substantial emer-

gence of hatchlings from the nest. The emergence of marine turtle

hatchlings is thought to be in response to declining ambient tempera-

tures (Bustard, 1972). Though most hatchling emergences from sampleU

nests occurred at night, a significant number occurred during afternoon

rain showers (10 percent of all loggerhead and green turtle sample

nests). Evidence indicating this phenomenon was the presence of a

depression resulting from the collapse of the egg chamber with hatchling

CLUTCH SIZE

170

150 -
�
.1 ....3~~~ ~0
0 .00 00
-130 - � ' .' .t. '

1 10 **..
~~~~~~�90 0

~~~~~70

80 s0 100 110

CLSL

Figure B. A scatter-graph showing the relationship between loggerhead
(Caretta caretta) clutch size (no. of eggs) and nesting
female straight-line carapace length (CLSL) in centimeters.
0 0 400
O00�
90 ' ' %

80 90 100 110

CLSL

Figure 8. A scatter-graph showing the relationship between loggerhead
(Caretta caretta) clutch size (no. of eggs) and nesting
female straight-line carapace length (CLSL) in centimeters.

TABLE 4

A table of correlations between sets of variables tested by Spearman's
Rank Order Correlation Coefficient (Rsp). The data source is a group of
green turtle (Chelonia mydas) nests/nesting females sampled from 21 km
of beach in south Brevard Co., Florida, 1985. Abbreviations: CLSL,
carapace length straight line of nesting female; IP, incubation period:
ES, emerging success of clutch; DD, date clutch was deposited; DO, date
female observed nesting; CS, clutch size.

Variables Tested n Pairs Rsp Significance
One-tailed (P)

CLSL/CS 17 0.40 0.05
CLSL/DO 18 -0.25 NS
CLSL/ES 16 0.26 NS
IP/CS 19 -0.28 NS
IP/DD 20 0.28 NS
IP/ES 20 0.04 NS
ES/CS 16 0.26 NS
ES/DD 25 -0.09 NS
CS/DD 26 0.08 NS

CLUTCH SIZE

200

180 - .

160

140 .

120

100

100 110 120

CLSL

Figure 9. A scatter-graph showing the relationship between green
turtle (Chelonia mydas) clutch size (no. of eggs) and nest-
ing female straight-line carapace length (CLSL) in centi-
meters.

tracks leading from this depression effaced by rain. When showers were

known to have occurred during daylight hours and not at night, this

evidence was assumed to indicate a daylight emergence.

Sixteen percent of all loggerhead and sixty-five percent of all

green turtle sample clutches exhibited multiple hatchling emergences

from the same clutch (modes = one and two emergences per clutch, respec-3

tively). Mean incubation period was 53 days for loggerhead and 54 days

for green turtle sample nests (Appendix tables 3 and 4).

No significant correlation was found between incubation period and

clutch size of either species (tables 3 and 4). Only loggerhead sample

clutches displayed a significant negative correlation between incubation

period and date of deposition (Table 3). Because incubation period is

known to shorten with increasing ambient temperatures (Bustard, 1972),

these findings are consistent with sand temperature data taken within

the nesting season. Average mid-berm sand temperatures at a depth of

40 cm were found to be 28.0, 28.5, 30.0, and 29.0 C for the months of

May, June, July, and August, respectively. Late-season sand temperature

probably did not influence the correlation of incubation period with

date of deposition, because many late-season sample nests were destroyed

by a September storm. Differences in loggerhead incubation periodI

between three zones of deposition were not found to be significant

(Table 5). The small number of green turtle sample nests within zones B

and C made a similar analysis invalid. Shaded and heavily vegetated1

nesting sites, known to influence incubation periods negatively (Fowler,

1979), were generally absent within the study area.

TABLE 5

A table of Kruskal-Wallis one-way ANOVA results for comparing incubation
periods of sample loggerhead (Caretta caretta) clutches from three zones
of deposition. Zone A is located nearest the dune escarpment, Zone C
nearest the surf and Zone B between zones A and C.

Zone of Deposition No. Nests ~ Incubation Period (days) Mean Rank

A 12 52.7 30.9
B 40 53.0 32.3
C 15 53.8 41.1

H = 2.63
P = NS

381

Analysis of Reproductive Success

Measures of Success

Values indicating reproductive success were calculated separately3

for sample nests not affected by a severe mid-September storm (non-storm

nests). The focus of the analysis of reproductive success centers on

these nests. The rationale for this is presented in the discussion3

section of this report. An analysis of clutch mortality caused by this

storm is given later in this section.

Values for three defined measures of reproductive success are

listed for loggerheads (Appendix Table 5) and green turtles (AppendixI

Table 6). Some sample clutches could not be relocated and were excluded

from analysis. Overall, reproductive success was judged quite high for

both species. Mean hatching and emerging success values for non-storm

loggerhead sample nests were 66 and 64 percent. These same measures

calculated for undisturbed loggerhead sample nests were 84 and 83

percent.I

Mean hatching and emerging success of non-storm green turtle sample

nests were 63 and 59 percent. These values did not differ significantly

from those of loggerhead sample nests (Table 2).

Sample size for the calculation of mean approximate ocean-boundI

success for both species was very limited, because assessment of this

measure was dependent on beach conditions which were not always ideal.

Assessments of approximate ocean-bound success were not made under

less-than-ideal conditions, but regardless of beach conditions, clutches

that were totally destroyed due to disturbances were known to have a

success of zero percent. For this reason, the mean values for

approximate ocean-bound success are probably artificially depressed. A

1 ~~~~~~~~~~~~~39

more accurate measure of post-emergence hatchling mortality is given

later in this section.

I ~~~~Three leatherback clutches marked within the study area failed to

hatch. No embryological development was detected within any of the

eggs. All eggs were entire, non-addled, had intact vitelline membranes

and were probably infertile.

The proportion of loggerhead sample nests which produced some

emergent hatchlings (emergence success) was 85 percent (Table 6). Green

I ~~~turtle emergence success was 80 percent. Undisturbed loggerhead and

green turtle nests had emergence success values of 95 and 100 percent.

Loggerhead emerging success was found to differ (P = 0.06) between

three zones of nest deposition (Table 7a). The results *of a Wilcoxon

I ~~~Rank-Sum Test revealed that central values of loggerhead emerging

success did not differ significantly between zones A and C (Table 7b).

Zone B, however, was found to contain nests which displayed higher

3 ~~~central values of emerging success than the more seaward zone (C) and

the zone closer to the dune vegetation (A).

No significant correlation was detected between emerging success of

loggerhead and green turtle sample nests and clutch size, date of

deposition, incubation period, and CLSL of the corresponding nesting

female (tables 3 and 4). A negative correlation between emerging

success and date of deposition indicated in Table 3 includes late season

I ~~~nests destroyed by the September storm.

An opportunity was afforded to compare values of emerging success

between subsequent nests of three different loggerheads (Appendix

j ~~~Table 5). Success was high for both clutches of one female (nest no.s

TABLE 6

Emergence success (ESS) of loggerhead (Caretta caretta) and green turtle
(Chelonia mydas) sample nests marked during the 1985 nesting season in
south Brevard County, Florida. Emergence success is defined in the
report text.

Nests Not Affected
Undisturbed Nests By September Storm Total Nests
ESS(%) n ESS(%) n ESS(%) n

Loggerhead 95.3 43 84.7 83 74.2 97
Green turtle 100.0 12 80.0 24 80.0 25

TABLE 7a

Tables of Kruskal-Wallis one-way ANOVA results for comparing measures of
emerging success of sample loggerhead (Caretta caretta) clutches from
three zones of deposition. Zone A is located nearest the dune escarp-
ment, zone C nearest the surf, and zone B between zones A and C.

ALL SAMPLE NESTS

Zone of Deposition No. Nests x Emerging Success (%) Mean Rank

A 15 52.7 43.2
B 50 64.7 54.9
C 31 42.3 40.8

H = 5.67
P < 0.06

NESTS NOT AFFECTED BY SEPTEMBER STORM

Zone of Deposition No. Nests x Emerging Success (%) Mean Rank

A 14 56.5 33.2
B 43 74.0 47.3
C 25 52.4 36.1

H = 5.58
P = 0.06

TABLE 7b

Tables of Wilcoxon Rank-Sum Test results for comparing measures of
emerging success of sample loggerhead (Caretta caretta) clutches from
three zones of deposition. Central values of emerging success for zones
with the same Roman numeral grouping are not significantly different at
the P = 0.05 level.

ALL SAMPLE NESTS

Grouping Zone of Deposition x Emerging Success (%)

I A 52.7
II B 64.7
I C 42.3

NESTS NOT AFFECTED BY SEPTEMBER STORM

Grouping Zone of Deposition x Emerging Success (%)

I A 56.5
II B 74.0
I C 52.4

1 ~~~~~~~~~~~~~43

8 and 9), but later clutches of the two others were destroyed by the

September storm. Subsequent clutch sizes were lower in all cases.

I ~~~~~~Factors Affecting Reproductive Success of Sample Nests

Descriptive fates of loggerhead clutches and those of constituent

eggs are listed in tables 8 and 9. Fates of green turtle clutches and

3 ~~~eggs are given in tables 10 and 11. Pie charts depicting clutch and egg

fates of sample nests are provided for loggerheads (figures 10 and 11)

and green turtles (figures 12 and 13). The following accounts of

success-limiting factors reinforce their depictions in these tables and

figures.

The breakage of eggs by the depositing female was rare, occurring

in only two green turtle nests and involving a total of five eggs. One

I ~~~instance of a nesting loggerhead uncovering a green turtle sample clutch

was recorded, but no damage was sustained by the clutch. Within

24 hours, however, the green turtle clutch was subjected to extensive

ft ~~~predation by raccoons. Though the uncovering of the nest was probably a

contributing cause, the fate of this green turtle sample nest was

categorized as having been destroyed by raccoons.

Sample clutches exposed to the affects of surf wash and erosion

were usually destroyed completely. The category "damaged by surf"

includes those clutches that were completely washed away or had develop-

ment arrested due to drowning. Among non-storm nests, surf damage

I ~~~played a relatively minor role in destroying 3percent of all loggerhead

sample clutches. Only one non-storm green turtle sample clutch was

destroyed by the surf.

j ~~~~Surf damage played a major role in destroying sample nests sub-

jected to the severe September storm. The observation that only those

TABLE 8

Descriptive fates of loggerhead (Caretta caretta) sample clutches marked
during the 1985 nesting season in south Brevard County, Florida.

No. of Nests
All Non-storm*

Undisturbed 43 43
Emerged 41 41
Did not emerge 2 2

Disturbed 54 54
Emerged 31 31
Ghost crab depredated 27 27
Raccoon depredated 1 1
Root infiltration 3 3
Affected by surf 0 0
Affected by sand accretion 0 0

Did not emerge 23 11
Ghost crab depredated 0 0
Raccoon depredated 6 6
Root infiltration 0 0
Affected by surf 12 3
Affected by sand accretion 5 2

Total 97 85

*Only those nests not affected by a September storm

TABLE 9

Descriptive fates of loggerhead (Caretta caretta) eggs constituting
clutches from sample nests marked during the 1985 nesting season in
south Brevard County, Florida.

No. of Eggs
All Non-storm*

Unhatched 4711 3299
Destroyed by surf 1374 370
Destroyed by sand accretion 542 212
Destroyed by ghost crabs 293 246
Destroyed by raccoons 772 772
Destroyed by plant roots 275 275
No apparent development 466 462
Development arrested with no
apparent physical disturbance 255 245
Contents putrefied with no
apparent physical disturbance 600 585
Hatchling died while pipping 134 132

Hatched 6554 6439
Hatchling died in nest (straggler) 88 85
Depredated in nest by ghost crabs 30 30
Depredated in nest by raccoons 105 105
Emerged from nest 6331 6219

Total 11,265 9738

*Only those eggs from clutches not affected by a September storm

Table 10

Descriptive fates of green turtle (Chelonia mydas) sample clutches
marked during the 1985 nesting season in south Brevard County, Florida.

No. of Nests
All Non-storm*

Undisturbed 12 12
Emerged 12 12
Did not emerge 0 0

Disturbed 13 13
Emerged 8 8
Ghost crab depredated 5 5
Raccoon depredated 0 0
Plant root infiltration 2 2
Affected by surf 1 0
Emergence artificially obstructed 0 0

Did not emerge 5 5
Ghost crab depredated 1 1
Raccoon depredated 1 1
Plant root infiltration 1 1
Affected by surf 1 1
Emergence artificially obstructed 1 1

Total 25 24

*Only those nests not affected by a September storm

TABLE 11

Descriptive fates of green turtle (Chelonia mydas) eggs constituting
clutches from sample nests marked during the 1985 nesting season in
south Brevard County, Florida.

No. of Eggs
All Non-storm*

Unhatched 1246 1122
Broken by nesting female 5 5
Destroyed by surf 142 142
Destroyed by ghost crabs 181 181
Destroyed by raccoons 131 131
Destroyed by plant roots 276 276
No apparent development 67 67
Development arrested with no
apparent physical disturbance 123 89
Contents putrefied with no
apparent physical disturbance 270 190
Hatchling died while pipping 51 41

Hatched 2340 2309
Hatchling died in nest (straggler) 21 21
Drowned in nest due to high surf 26 0
Emergence blocked 136 136
Emerged from nest 2157 2152

Total 3586 3431

*Only those eggs from clutches not affected by a September storm

Figure 10. Clutch fates of loggerhead (Caretta caretta) sample
nests marked within the Melbourne Beach study area in
1985.

Caretta caretta
CLUTCH FATES
nr 85
EMERGED UNDISTURBED
41

3 DAMAGED BY SURF
2 NO DEVELOPMENT

1 '" 7 DAMAGED BY
3 , RACCOONS
INFILTRATED BY 2A '' ' A' ' '
PLANT ROOTS " 2 DAMAGED BY ACCRETION

27
DEPREDATED BY
GHOST CRABS

-11 w t

Figure 11. Fates of consitutent eggs from loggerhead (Caretta caretta)
sample nests marked within the Melbourne Beai-chstudy area
in 1985.

Caretta caretta

EGG FATES
n=9738

',, ~OTHER
HATCHUJNGS EMERGED G OT

DESTROYED BY
246 GHOST CRABS

582 DESTOYED BY SURF
OR ACCRETION
772 DESTROYED BY RACCOONS

DESTROYED BY
PLANT ROOTS

Figure 12. Clutch fates of green turtle (Chelonia mydas) sample
nests marked within the Melbourne Beach study area in
1985.

Chelonia mydas
CLUTCH FATES
n-24
EMERGED UNDISTURBED

1 DEPREDATED BY
RACCOONS
EMERGENCE OBSTRUCTED
DAMAGED BY SURF
DEPREDATED BY
GHOST CRABS 3
INFILTRATED BY
PLANT ROOTS

- -~~~~~~~~~1

m -mm - - - rm

Figure 13. Fates of constituent eggs from green turtle (Chelonia mydas)
sample nests marked within the Melbourne Beach' study area
in 1985.
Chelonia mydas
EGG FATES
n=3431
HATCHUNGS EMERGED
2,152

142 DESTROYED BY SURF
131 DESTROYED BY
RACCOONS
181
DESTROYED BY
;^ . 276 GHOST CRABS
549
OTHER DESTROYED BY
PLANT ROOTS

nests lower on the beach suffered arrested embryological development

attested that surf wash, not rain, was the primary cause of failure for

storm-affected nests. One storm-damaged nest contained hatchlings that3

had apparently drowned during their ascent to emerge.

Accretion of sand over loggerhead clutches was an unusually

,destructive occurrence. All affected nests were totally destroyed with3

embryological development arrested very early or midway throug-h 1.ncuba-

tion. The amount of sand accreted could, in all cases, be determined by

the depth of the aluminum disc used to mark the nest. Up to 75 cm of

sand was found to have been deposited over destroyed clutches. TheI

ultimate cause of failure in these clutches was most likely suffocation.

The zone of accretion was at the center of the berm, just above the

spring high-tide mark. A substantial amount of accretion seemed to have5

been associated with the September storm, though this accretion occurred

much higher on the berm. No green turtle nests were affected by this

phenomenon.3

The major predator of eggs within the study area was the raccoon

(Procyon lotor). Raccoons were very efficient in completely consuming

or destroying nearly all the clutches they deprediated. Seven percent of

all loggerhead sample clutches were deprediated by raccoons. AllI theseI

clutches were totally destroyed, except for a clutch deprediated just

pre-emergence from which several hatchlings escaped. The only green

turtle sample clutch deprediated by raccoons was one previously mentioned3

that had been uncovered by a nesting loggerhead. This clutch was

completely destroyed.

Nests deprediated by raccoons were not inventoried until a timep

suitable for the incubation of any remaining eggs had passed. In all

� ~~~~~~~~~~~~~~53

cases, eggs remaining in the nest were found to be addled due to contact

with the contents of other eggs which had been broken.

I ~~~~~All but one sample nest deprediated by raccoons was done so between

20 and 40 days post-deposition. This was surprising, inasmuch as during

this period, most apparent visual and olfactory cues had been effaced.

Predation by ghost crabs (Ocypode quadrata) was common among

loggerhead and green turtle clutches. Ghost crabs invaded a substantial

fraction of both species' clutches, yet destroyed only a small percent-

age of eggs. Thirty-two percent of all loggerhead and 25 percent of all

green turtle sample nests were invaded by ghost crabs; however, only 2

and 5 percent of the constituent loggerhead and green turtle eggs were

destroyed. These figures of egg damage include several instances where

5 ~~~ghost crabs caused substantial secondary damage. As observed in raccoon

deprediated nests, eggs adjacent to other broken ones were often addled.

Although differences exist in ghost crab predation rates between the two

3 ~~~species, they are not significant (binomial two-population test,

P < 0.05). Ghost crabs were also known to have taken hatchlings from

pre-emergence clutches. This rate for loggerheads was 0.3 percent.

While this value is probably underestimated slightly, it is also quite

I ~~~insignificant.

Ghost crabs were the sole predator of post-emergence hatchlings

from sample nests. Data from evidence of post-emergence predation were

3 ~~~pooled with other random observations and are discussed later in this

section.

A curious form of "predation" affecting sample nests was the

g ~~~destructive invasion of clutches by plant roots. Plants involved were

primarily beach morning-glory vine (Ipomoea pes-caprae) and in a single

541

case, sea oats (Uniola paniCulata). Incidents of plant root invasion

were too infrequent to statistically ascertain differences in rates

between species. It does seem, however, that green turtles suffered a3

greater clutch invasion rate (12%) and egg destruction rate (8%) than

did loggerheads (3% of clutches and eggs invaded and destroyed).

For a substantial number of sample nest eggs, embryological devel-3

opment was arrested with no apparent major physical disturbance. Other

eggs gave the appearance of being infertile. Because no microscopic

examination of each egg was attempted and the fertility of eggs

destroyed by predators was unknown, no conclusions specifically quanti-I

fying fertility were made. Observations of eggs known to have resulted

in some embryological development, however, make the assessment of

minimum fertility rates valid. Minimum fertility rates were 70 percentI

for loggerheads and 71 percent for green turtles. Seemingly infertile

eggs, putrified or addled eggs, and eggs which were arrested during

development made up 13 percent and 10 percent of all loggerhead and

green turtle eggs.

Recognizable teratological deformities of loggerhead and green

turtle embryos are presented in Table 12. Most deformities were mani-

fested in white, late developing fetuses as described by CaldwellI

(1959a). As he observed and as McGehee (1979) also observed, no single

clutch had a preponderance of deformed individuals. All deformities

mentioned were major ones, primarily of the cephalic region. One3

clearly dicephalous green turtle hatchling was found.

One percent of all loggerhead and green turtle eggs resulted in

fully-formed hatchlings that pipped their eggs but could not success-

fully extricate themselves from their shells. About 0.9 and 0.6 percent

TABLE 12

A summary of teratological deformities observed in nest-trapped hatch-
lings and term embryos from sample nests of marine turtles marked during
the 1985 nesting season in south Brevard County, Florida.

Loggerhead (Caretta caretta) Green Turtle (Chelonia Mydas)
No. Individuals No. Nests No. Individuals No. Nests

Hatchlings 4 4 of 97 3 3 of 25
Term Embryos 13 10 of 97 8 4 of 25

of all loggerhead and green turtle eggs resulted in hatchlings that

extricated their shells but did not emerge from the nest. Some of these

hatchlings displayed carapace or flipper deformities and are included in5

Table 12. Live hatchlings remaining in the nest are known to be

unable to emerge without the group effort provided by their siblings

(Carr and Hirth, 1961). Although designated as dead, these live nest-3

trapped hatchlings were released into the surf when found.

Some mortality incurred by sample' nests could be directly or

indirectly attributed to humans. One loggerhead nest was apparently

subjected to the damaging effects of a four-wheeled vehicle prior toI

being deprediated by raccoons. Although uncovering the clutch likely led

to an enhanced probability of depredation, direct damage caused by the

vehicle was unknown.5

One green turtle nest, rescued from a predictable fate, is catego-

rized under "obstructed emergence" in tables 10 and 11. A sizable load

of Casuarina logs was piled over the clutch inadvertently, in an attempt 3

by the beachfront property owners to stabilize the dune. Concluding

that the clutch would have been lost without intervention, a portion of

the debris was removed so that the clutch could emerge. The frequency

and extent of such illegal dune reconstruction practices within the

study area assured that the designation of this clutch as destroyed

would not be misrepresentative.

Disorientation by artificial beachfront lighting was a major cause3

of post-emergence hatchling mortality. Data concerning disorientation

rates of sample nests were pooled with random observations of natural

emergences and are discussed later in this section.

1 ~~~~~~~~~~~~~~57

Marine turtle nests incubating within the study area suffered

considerable damage due to a severe storm which lingered from 15 to

20 September. Evidence from sample nests quantifying the rate of

destruction was reinforced by observations of randomly marked natural

nests. The effects of storm-generated erosion were monitored relative

I ~~~to the placement of these nests. Three of four green turtle sample

nests incubating at the onset of the storm survived while only two of

fourteen loggerhead nests did. These rates closely matched those

j ~~~estimated from observations of the randomly marked nests. Nests impac-

ted by the storm's effect were typically destroyed completely while

unimpacted nests displayed relatively normal success. At the storm's

onset, 53 percent of all green turtle nests were still incubating, while

only 23 percent of all loggerhead nests were (based on known temporal

nesting distributions). Taking into account the number of nests present

and the ratio of destruction for each species, an estimate of storm-

I ~~~related mortality was calculated. Overall mortality this September

storm was about 13 percent of all green turtle and 19 percent of all

loggerhead clutches.

3 ~~~~Two tropical storms, Bob (24 July) and Elena (I September), passed

but did not linger near the study area and caused little or no signifi-

cant damage to marine turtle nests. The effects of Hurricane Gloria

(26 September) were felt only moderately within the study area, and it

I ~~~is doubtful whether any nests not already destroyed by the previous

storm were affected.

Analysis of Daily Quantitative and Qualitative Observations

3 ~~~~~~Mortality Influenced by Numbers of Nesting Females

Clutches destroyed by other nesting females were observed and

tallied during daily nesting surveys. One case of a leatherback dis-

turbing a loggerhead clutch, nine cases of loggerheads disturbing

loggerhead clutches, three cases of green turtles disturbing loggerhead3

clutches and one case of a loggerhead disturbing a green turtle clutch

were noted. Most of these clutches suffered subsequent depredation by

raccoons, ghost crabs and/or fish crows (Corvus ossifragus). These

tallies probably underrepresent somewhat the actual frequency of events.

Ghost Crab Predation

Outwardly visible signs of subterranean ghost crab predation

(broken shells near burrow spoils) were obviously underrepresentative.I

Discernment of spatial patterns in ghost crab predation, therefore, was

limited to systematic observations involving burrow placement. Fifty-

eight observations were made for each of three substrate conditions:I

fresh loggerhead nests, old loggerhead nests, and undisturbed beach. An

analysis of these observations is presented in Table 13. There was a

significantly greater probability of encountering ghost crab burrows in

fresh loggerhead nests than in old nests or in randomly-chosen undis-

turbed beach plots. Surprisingly, there was also a significantly

greater proportion of ghost crab burrows in undisturbed beach than in

old nests. Casual observations of areas of beach with fresh shovel-I

disturbed sand similarly indicated that ghost crabs preferred this

freshly-disturbed sand to undisturbed surrounding beach.

Ghost crabs were found to be the only major predator of post-3

emergence hatchlings. This predation is discussed under the division on

post-emergence mortality.
Raccoon Predation

Conclusions on the nature and extent of raccoon predation on marineI

TABLE 13

Occurrences of ghost crab (Ocypode quadrata) burrows within randomly
chosen 1m2 quadrats at various locations. The study was carried out
within 21 km of beach in south Brevard County, Florida on 29 May, 1985.
Proportions were compared, using a binomial two-population test.

1 - Random, above high tide mark

2 - Fresh loggerhead nest

3 - Loggerhead nest two or more days old

Quadrat Location
Burrows Present 1 2 3

Yes 18 26 10
No 40 32 48

Total n 58 58 58
n 0.31 0.45 0.17

Ha Test Statistic Significance (P)

r1 > w3 2.8 0.003
i2 > r3 4.2 < 0.001
I2 > 1 2.1 0.02

turtle clutches within the study area were based on 408 observations of

raccoon-disturbed nests. Disturbances to nests were judged by outwardly

visible signs to have occurred either within 24 hours (fresh), before3

pipping (early incubation), after pipping (late incubation), or after

hatchlings had already left the nest (post-emergence). Two categories,

early and late incubation, were known to overlap somewhat, because of

difficulties in discerning sign. The proportions of clutches disturbed

during these incubation milestones are represented in Figure 14.

Clearly, a negligible percentage of nests were disturbed by raccoons

while they were still fresh. Strangely, the vast majority of destroyedI

clutches (- 78%) were disturbed during early incubation, when most

visual and olfactory cues have been effaced. These data correspond to

findings from carefully-monitored sample nests. About 21 percent of all

clutches that were destroyed were disturbed during late incubation or

just pre-emergence, when olfactory cues from pipping hatchlings are

present. These olfactory cues appear to have lingered long enough to

prompt raccoons to dig up post-emergence nests from which hatchlings had

already escaped. These cases constituted 40 percent of all disturbances

and probably resulted in little mortality to hatchlings.

Raccoons were observed frequently to have capitalized on distur-I

bances to nests created by extraneous sources. Three nests uncovered by

vehicular traffic and five nests uncovered by nesting turtles were found

to have been subsequently deprediated by raccoons.

The temporal distribution of disturbances to nests caused by

raccoons is compared to the temporal distribution of loggerhead nesting

activity in Figure 15. Raccoons did not begin to fully exploit the

beach until half of the nesting season had passed. Hopkins and Murphy

am s m m

Figure 14. Marine turtle clutches depredated by raccoons during
specific milestones of incubation. Events were tallied
during daily surveys within the Melbourne Beach study area
in 1985.

n=408
193 EARLY INCUBATION

3 FRESH NESTS
LATE ,32 18 UNKNOWN
INCUBATION &
PRE-EMERGENCE

162 POST-EMERGENCE

625

(1980), and Gallagher et al. (1972) also found raccoon predation to

intensify later in the nesting season; however, this pattern is greatly

exaggerated on Melbourne Beach due to an uncommon lack of fresh nest

predation.

The spatial distribution of nest disturbances by raccoons is

represented in Figure 16. Three sections in the southern portion of the3

study area clearly had substantially elevated levels of raccoon preda-

tion, compared to the surrounding sections. These three sections (17,

18, and 19) contained 63 percent of all the observed incidents. In

Figure 16, relative raccoon population density throughout the study area

is represented by the frequency of road-kills occurring along highway

AIA. The distribution of road-kills appears to exhibit no correspon-

dence with the distribution of predation.I

Minor Forms of Predation

Ants (Formicidae) were a commonly observed secondary predator to

previously disturbed clutches, but probably initiated little damage by3

themselves.

Fish crows were the primary avian predator of eggs and hatchlings.

Some egg predation may have been initiated by fish crows, though most

often they appeared to have simply shared in the spoils of nests openedI

by raccoons. Crows, being efficient scavengers, seemed to play a major

role in removing dead and dying hatchlings that remained on the beach

due to disorientation by beachfront lighting. Laughing gulls (Larus3

atricilla) were observed on two occasions to possess live and dead

hatchlings, though the area and manner of predation were not known.

Domestic dogs were common within the study area, though theirI

presence on the beach was prohibited by a county ordinance. Dogs dug

m - m m - m m

Figure 15. The relationship between the temporal distributions of
loggerhead nesting and raccoon predation on marine turtle
clutches within the Melbourne Beach study area in 1985.
3D
- 200
I -s- RACCOON PREDATION 200
LOGGERHEAD NESTING
25

-210

120
15-

6 --/ - 40

0 I I I I I I 0
130 150 170 190 210 230 250 270
JULIAN DATE

Figure 16. The spatial (horizontal) distributions of raccoon
predation and raccoon road-kills on Highway A1A
within the Melbourne Beach study area in 1985.
30- Section one is located five kilometers south of
5th Avenue in Indialantic, Florida.

25- RACCOON ROAD-KIS I
RACCOON PREDATION x

ROAD-KILLS n=25
PREDATION n=408 K
0 X

x x

x x x

X X X

x x
5- x
O - K KX

1 3 5 7 9 11 13 15 17 19 21
LOCATION (one km sections)

_ _ _ _ _

5 ~~~~~~~~~~~~~~65

extensively on the beach but apparently caused no damage to marine

turtle clutches. Emerging hatchlings were known, however, to have been

trapped in the resultant holes.

Mortality Attributable to Humans

One clutch of loggerhead eggs was observed to have been taken by

3 ~~~humans. Because poachers typically take fresh eggs from easily identi-

fied nests, all nests within the study area were observed during the

time they were most susceptible to poaching. In addition to one nest

taken, two other nests bore evidence of attempts to locate their eggs.

Vehicular traffic, banned on Brevard County beaches, appeared to

continue sporadically with apparent impunity. On frequent occasions,

evidence of large four-wheeled vehicles was observed on the beach. In

several instances, deep ruts seriously delayed emerging hatchlings from

reaching the surf. Nests being crushed by such traffic are documented

by Mann (1977), though the extent of this mortality at Melbourne Beach

* ~~~was unknown.

Illegal dune reconstruction activities probably accounted for the

destruction of a large number of marine turtle clutches; however, the

extent of this mortality could not be quantitatively documented.

Truckloads of sand were dumped over the dune onto the beach within four

100 m stretches of beach within the study area. It is reasonably

certain that the nests beneath the dumped sand were suffocated . The

5 ~~~use of heavy earthmoving equipment on the beach to aid in depositing the

sand probably caused additional mortality.

Disorientation of hatchlings by artificial beachfront lighting was

a major form of mortality attributable to humans. Hatchling disorienta-

tion is discussed in the following division.

Post-Emergence Hatchling Mortality

Ghost crabs were found to be the only major post-emergence predator

of non-disoriented clutches. Because conditions revealing evidence of

post-emergence hatchling mortality were not always ideal, evidence from

sample nests was limited. An analysis was made from 48 observations of

sample nests and randomly-chosen, natural hatchling emergences. An

average of 0.5 hatchlings were taken by crabs from each hatchling

emergence. Because many clutches had multiple hatchling emergences, the

average number of hatchlings lost per clutch was slightly higher. These

estimates are based on loggerhead hatchling emergences. Although green

turtle hatchlings are slightly larger and may avoid some crab predation,

green turtles also appear to display a greater frequency of multiple

hatchling emergences. Regardless of an exact quantification, however,

post-emergence hatchling mortality for both species was assuredly quite

small.

Evidence of hatchling emergences disoriented by beachfront lighting

was widespread. This phenomenon has been extensively documented by

Raymond (1984a). Mortality suffered by disoriented clutches was judged

by Mann (1977) to be very extensive, if not complete. This mortality is

difficult to quantify because of the efficiency of scavengers in remov-

ing dead and dying hatchlings from the beach, the confusion of the

resulting sign, and the uncertain fate of hatchlings that manage to

enter the sea after a night of disorientation.

Hatchling disorientation rates of clutches were determined from

observations of 1290 random, naturally occurring hatchling emergences.

The spatial distribution of hatchling disorientation within the study

area is represented by Figure 17. This distribution corresponds very

closely to the areas of higher density development depicted by Figure 1,

and consequently, areas with greater concentrations of beachfront

lighting (observation).

Hatchling disorientations were judged as being major or minor.

Table 14 lists the number of major and minor hatchling disorientations

by ten-day periods. Of all hatchling disorientations, 64 percent were

major and 36 percent were minor. Averaged for the season, 7.5 percent

of all hatchling emergences within the study area were disoriented by

beachfront lights.

This analysis of hatchling disorientation was based primarily on

loggerhead hatchlings. With reasonable certainty, green turtle hatch-

ling emergences could be differentiated from loggerhead ones. It is

notable that no major hatchling disorientations were observed of green

turtle clutches.

Recognizing the threat to marine turtle reproductive success, the

Brevard County Commission adopted an ordinance restricting beachfront

lighting. This ordinance was promulgated prior to the 1985 nesting

season, but its effects were not immediately observed. Figure 18

displays rates of hatchling disorientation broken down by ten-day

periods. Initially, over ten percent of all hatchling emergences were

disoriented. Letters sent to beachfront residents by the Brevard County

Planning Department and a door-to-door campaign to raise awareness of

the lighting ordinance were successful in darkening many problem areas.

Following these actions taken to darken the beach, rates of hatchling

disorientation within the study area were immediately reduced.

Hazards to Nesting Females

No mortality to nesting marine turtles was observed within the

Figure 17. The spatial (horizontal) distribution of hatchling
disorientation within the Melbourne Beach study area
in 1985. Hatchling disorientation is expressed as a
percentage of total hatchling emergences. Section one
30 - is located five kilometers south of 5th Avenue in
Indialantic, Florida.

25-

20-

o15 -

10-

0
1 3 5 7 9 11 13 15 17 19 21
LOCATION (one km sections)

TABLE 14

Marine turtle hatchling emergences and disorientations observed on 21 km
of beach in south Brevard County, Florida, 1985. Major disorientations
are those which involve the majority of a clutch's constituents, while
minor disorientations involve the minority. Observations are pooled
into seven, ten-day periods.

No. Observed Disorientations
Date (1985) No. Observed Emergences Minor Major

7-16 July 212 6 22
17-26 July 133 6 14
27 July-5 August 348 12 6
6-15 August 226 4 12
16-25 August 177 1 6
26 August-4 September 79 5 0
5-14 September 115 1 2

Total 1290 35 62

Figure 18. The temporal distribution (by ten-day increments) of
hatchling disorientation within the Melbourne Beach study
area in 1985. Hatchling disorientation is expressed as
a percentage of total hatchling emergences. The arrow
12 - indicates the date at which an effort was made to darken
specific hatchling disorienting lights.

IC~~~~~)C
10- )

ACTION TAKEN TO
DARKEN BEACH
6_
Q 0

2-
~>00<

188 198 208 218 228 238 248
JULtAN DATE
BEGINNING DATE OF TEN DAY PERIOD

m _ m m a -

1 ~~~~~~~~~~~~~~~71

study area. However, two subadult loggerheads (55-70 cm CLSL) that had

apparently expired due to drowning and boat collisions were found washed

I ~~~ashore within the study area. Shrimp trawling, an activity associated

with elevated mortality of turtles offshore waiting to nest (Hillestad

et al., 1978), was observed only infrequently off the study area.

3 ~~~~Observations of injuries to nesting turtles were few. One nesting

loggerhead was found trapped beneath a wooden boardwalk during a daily

nesting survey. The turtle was freed' with no apparent deleterious

effects. Evidence was observed of a nesting green turtle that had

apparently undermined a cement block wall which partially collapsed on

it, causing unknown damage to the turtle. Sign was also observed of a

loggerhead that became trapped within a trench dug as part of a dune

3 ~~~reconstruction project. The turtle apparently escaped after some

extensive effort.

Human interference with nesting turtles was rather uncommon and,

3 ~~~for the most part, unintentional. Evidence of nesting turtles being

disoriented by bright, beachfront lights was observed, though this

phenomenon was eliminated when the offending lights were dimmed.

Non-nesting emergences prompted by difficulties in digging amidst

I ~~~sandbags and by the flashlights of well-intentioned "turtle watchers"

were the only other human hinderances to marine turtle nesting attempts.

Analysis of Hatchlinq Production

3 ~~~~The following quantification of hatchling production takes into

account all mortality incurred during the terrestrial portion of the

life histories of loggerheads and green turtles nesting at Melbourne

3 ~~~Beach in 1985. Although this analysis provides an accurate assessment

of hatchling production in 1985, the accuracy of future estimates will

probably depend on variations in a few major causes of mortality. Two

mortality factors which seem quite variable are mortality due to severe

storms and mortality due to hatchling disorientation by artificial

lighting. Mortality from both of these sources has been excluded from

one of the following calculations, to represent a year in which no major

storms strike and the problem of hatchling disorientation has been dealt

with effectively. Some assumptions made are that loggerheads and green

turtles suffer about the same level of post-emergence mortality and that

green turtle hatchlings suffer negligible levels of mortality due to

disorientation. Major hatchling disorientations are assumed to suffer

100 percent mortality while minor ones are ignored. These definitions

accompany the analysis:

ES: mean emerging success of non-storm nests.

ESS: emergence success of non-storm nests.

CS: mean clutch size.

PEM: post-emergence mortality of hatchlings per non-disoriented clutch.

RHD: rate of hatchling disorientation among emerged clutches.

N: total nests deposited within the study area.

S: total nests not destroyed by storms.

TPH: total number of potential hatchlings = N x CS.

Production: the percentage of all potential hatchlings (yolked eggs)

that successfully reach the surf.

The units of intermediate values in this analysis are numbers of

eggs/hatchlings. A "model" year is one in which no severe storms strike

and hatchling disorientation is negligible.

Loggerhead Production _ (ESxSxCS)-[(PEMxESSxS)+(SxCSxESSxRHD)]
in 1985 TPH

_ 615,244-(4936 + 39,329)
1,189,888

570,979
1,189,888

= 48.0%

Loggerhead Production _ (ESxNxCS)-(PEMxESSxN)
in a Model Year TPH

756,769 - 6071
1,189,888

_ 750,698
T1,189,888

= 63.1%

Green Turtle Production _ (ESxSxCS) - (PEMxESSxS)
in 1985 TPH

_ 20,760 - 137
40,661

_ 20,623
40,661

= 50.7%

Green Turtle Production _ (ESxNxCS) - (PEMxESSxN)
in a Model Year TPH

_ 23,908 - 157
40,661

_ 23,751
40,661

= 58.4%

In 1985, an estimated 570,979 loggerhead hatchlings and 20,623

green turtle hatchlings left Melbourne Beach. Numbers of hatchlings

produced in model years will vary depending on nesting densities.

Analysis of Data Incidental to Nightly Excursions

Of 301 loggerheads and 29 green turtles checked for previous tags,

17 percent and 14 percent, respectively, bore tags or evidence of tag5

loss. One green turtle and 39 loggerheads bore tags or tag remnants

from which they could be fully or partially identified. Identifiable

recoveries of nesting loggerheads are listed with their original loca-3

tions and growth data in Appendix Table 7. Turtles originally tagged at

the Kennedy Space Center Beach, Florida, were done so by L. M. Ehrhart.

Tags with the prefixes B, C, E, and G were applied originally on Mel-

bourne Beach by B. J. Turner. Tags with the prefixes D and T, and those

beginning with the number 16, were applied on Melbourne Beach by P.W.

Raymond and L. M. Ehrhart. Tags with the prefix SI were applied by

Caretta Research, Inc., on Melbourne Beach. Tags with the prefixes FL3

and GA were applied, respectively, at the Canaveral National Seashore

and Little Cumberland Island, Georgia, by J. I. Richardson.

Of 39 identifiable loggerhead recoveries, 33 were from Melbourne3

Beach, 4 were from the Kennedy Space Center beach, one was from the

Canaveral National Seashore, and one was from Little Cumberland Island.

Based on dates of recovery, Melbourne Beach loggerheads appear to

be nesting on two- and three-year cycles (Appendix Table 7). These data

agree with evidence gathered by Richardson et al. (1978) on Georgia

loggerheads and Bjorndal et al. (1983) on Florida loggerheads.

Growth rates of recovered loggerheads are compiled in Appendix3

Table 7. Except in one extreme case, negative growth data were included

in calculating mean rates. Mean increase of loggerhead carapace length

(straight line) was 0.15 cm/yr (SD = 0.24 cm/yr, n = 23) and mean

carapace width (straight line) increase was 0.16 cm/yr (SD = 0.33 cm/yr,

n = 21).

Intraseasonal recoveries were relatively uncommon. One loggerhead

was observed nesting on Hutchinson Island, Florida, and a green turtle

was observed nesting on Jupiter Island, Florida, after being tagged

within the study area in 1985 (P. R. Witham, pers. comm.). Six logger-

heads were observed during subsequent nesting attempts on Melbourne

Beach. The average distance between nests of these turtles was 3.8 km,

with a range of 18 to 77 days between nestings. One green turtle was

observed nesting 29 days after she was initially observed and 0.05 km

from her original nesting site.

DISCUSSION

Nesting Densities and Distributions

Nesting densities for loggerheads and green turtles in 1985 wereI

the highest observed for the 21 km study area since surveys began four

years ago (Table 1; Ehrhart and Raymond, ins.). Hobe Sound National

Wildlife Refuge, Florida, also registered record densities of loggerhead3

and green turtle nests (Marcus, 1985). This information, together with

reports from Hutchinson Island, Florida (Erik Martin, pers. comm.) and

Sebastian Inlet State Recreation Area (Perry Smith, pers. comm.),3

confirms that 1985 was a very good nesting year for both species over a

fairly broad geographic range in Florida.I

While loggerhead nesting density at Melbourne Beach was indeed

high, the relative increase in green turtle nesting in 1985 was muchU

higher (Table 1; Ehrhart and Raymond, ins.). This phenomenal increase

certainly indicates a substantial augmentation of nesting green turtles

in 1985, but its relevance to overall population numbers is question-3

able. Green turtles are known to exhibit marked fluctuations in nesting

densities from year to year at the Tortuguero, Costa Rica nesting beach

(Meylan, 1982). These fluctuations are thought to indicate coinciding

cycles in nesting activity among groups of nesting females. Because
green turtles nest on two and three year cycles (Bjorndal et al., 1983;

Carr and Ogren, 1960), this pattern would be expected to manifest itself

in a relatively "poor" year for green turtle nesting in 1986. On the3

* ~~~~~~~~~~~~~~77

other hand, the extraordinary green turtle nesting in 1985 may indeed

indicate the simultaneous arrival of a large cohort of recruits to the

I ~~~population of nesting females, or a concentrated immigration of nesting

animals from other beaches. The latter possibility appears more realis-

tic when one considers the dramatic effect that artificial beachfront

3 ~~~illumination has on discouraging green turtle nesting. It may be that

beachfront lighting is capable of drastically altering the distributions

of green turtle nesting activity along Florida's coast. The superficial

3 ~~~indication that the increase in numbers of nesting green turtles was

actually a state-wide trend, however, bestows additional credence to

Pritchards (1982) conclusion that Florida's endangered population of

green turtles is slowly recovering.

I ~~~~Although seasonal variation in loggerhead nesting numbers is much

more subtle than that of green turtles, some cyclic fluctuations have

been observed. In fact, the "good" nesting year of 1985 corresponds to

another "good" year in 1983 at Melbourne Beach (Ehrhart and Raymond,

ins.) and Florida in general (Harris et al., 1984).

In the past 40 years or so, leatherbacks have been known to nest

3 ~~~only sporadically along Florida's coast (Caldwell, 1959b, Harris et al.,

1984). Leatherbacks nest almost exclusively on tropical beaches, so

their minor participation in nesting at Melbourne Beach was not surpris-

i ng.

I ~~~~Despite large daily variations in nesting activity, the nesting

season for each species began and ended discretely (figures 3 and 4).

Although loggerhead and green turtle nesting seasons broadly overlapped,

3 ~~~a clear temporal partitioning was evident between the two species.

Initial nesting of green turtles did not take place until one month

after the first loggerhead nesting. As a result, the date at which the

greatest number of loggerhead nests were incubating (22 July) was widely

separated from that of green turtles (19 August). Because the green3

turtle nesting season was shorter, green turtles also had a greater

percentage of nests incubating at this time than did loggerheads.

The devastating impacts of northeaster fall storms on late-season

nest success may offer substantial selective pressure for marine turtlesU

to nest during the more quiescent summner months. Nests of green tur-

tles, however, are situated higher on the dune than are loggerhead nests

(Table 2), which affords them some protection from storm-generated

damage. Although the northeaster storms and surf erosion typical of the

fall months generally selects against late season nesting, green turtles

are apparently able to exploit nesting times later in the season than3

are loggerheads.

Another physical factor that may dictate the temporal realm of

marine turtle nesting activity is temperature. Temperature is known to

have profound effects on marine turtle clutches with respect to embryo -

logical development and survival (McGehee, 1979, Bustard, 1972), incuba-

tion period, and even the sex of the resulting hatchlings (Mrosovsky,

1980). Lower sand temperatures may be significant in restricting3

nesting of both species to the late spring and summer months.

Temporal partitioning between nesting loggerheads and green turtles

has also been observed for the same species on the densely-nested island3

of Masirah, in the Indian Ocean (Ross and Barwani, 1982). A relatively

high rate of density-dependent nest destruction is reported to occur at

Masirah. In the past, Melbourne Beach may have also supported nesting

of both species dense enough to conduce similar mortality. TemporalI

* ~~~~~~~~~~~~~~79

partitioning within physical limitations may have been very advantageous

to each species in avoiding this mortality.

I ~~~~Spatial distributions of nesting activity also varied between

species at Melbourne Beach. The horizontal (along the beach) distribu-

tion of loggerhead nesting in 1985 (Figure 5), closely resembles the

distributions for three previous years (Ehrhart and Raymond, ins.). Such

static distributions in nesting activity are speculated by Provancha and

Ehrhart (ins.) to correlate with static discontinuities in beach profile.

3 ~~~Hopkins and Murphy (1980) observed that drastic changes in beach profile

on a South Carolina barrier island caused by a severe storm, substant-

ially altered the horizontal distribution of nesting loggerheads.

Within the Melbourne Beach study area, no objective investigation was

* ~~~made into relationships between nesting densities and natural beach

attributes. There does certainly exist, however, some distinctly

alluring attribute or set of attributes that consistently draws nesting

3 ~~~turtles to Melbourne Beach. An analytical recognition of these attri-

butes would be imperative, if any large scale beach reconstruction or

renourishment projects are proposed for this important nesting beach.

3 ~~~~The horizontal nesting distribution of green turtles (Figure 6)

differed greatly from that of loggerheads. One attribute of the study

area beach that apparently governed this distribution in green turtles,

was the incidence of artificial beachfront lighting. Nesting green

* ~~~turtles clearly shunned areas of the beach that were brightly lighted to

a much greater extent than loggerheads. Because nesting green turtles

avoided lighted areas, their hatchlings were apparently not subjected to

* ~~~the disorientation and resulting mortality suffered by clutches that

emerge in proximity to bright lights. Avoidance of lights was probably

not a trait directly selected for in the evolution of green turtle

nesting behavior. Such an increased discrimination in nest site choice,

however, may have indeed promoted greater reproductive success, thereby

fostering the genes of more discriminating animals. This

notwithstanding, a definite spatial separation of nesting between

species has resulted from the differential propensities governing

loggerhead and green turtle nest site choice.

Although the horizontal distribution-of loggerhead nesting activity

was apparently affected minimally by beachfront lighting, loggerheads

did seem to abort nesting attempts at a greater frequency in lightedI

areas (Figure 7). It is interesting to note that loggerheads aborted

nesting emergences at a significantly higher frequency than green

turtles. This may indicate when the "decision" to emerge and nest is

made for each species. Green turtles may scrutinize nest-site choice to

a greater extent pre-emergence, rather than while traversing the beach.

Loggerheads and green turtles also differed by the pattern in which

their nests were distributed vertically along the beach grade (Table 2).

Green turtles primarily chose nesting sites directly at the base of the

primary dune, while loggerheads preferred the flat berm midway between

the dune and the spring high-tide mark. Unlike loggerheads, green3

turtles undertake massive excavations while nesting, which are poten-

tially destructive to any adjacent clutches. In addition, green turtle

clutches are deposited deeper than loggerhead clutches and are better

able to withstand similar assaults by nesting loggerheads. Although

clutches deposited higher on the beach are better able to withstand

storm-generated erosion, it may have been adaptively beneficial for

loggerheads to adopt otherwise less-successful nesting sites seaward of

the primary dune.

I ~~~~Manmmalian predation may have also played a role in shaping vertical

nesting distributions. A subjective appraisal of the vertical distribu-

tion of raccoon predation within the study area revealed what Routa

3 ~~~(1967) also observed, that nests closer to the vegetated dune were

deprediated more frequently than nests farther out on the berm. The

depth at which green turtle clutches were deposited appeared to discour-

3 ~~~age predation and may allow green turtles to more successfully exploit

dune-base nesting sites.

Turtle Size, Clutch Size and Incubation Period

Incubation period length of marine turtle clutches is known to vary

I ~~~negatively with temperature (Bustard, 1972; Mrosovsky, 1980). Dispari-

ties in incubation period between Melbourne Beach and other nesting

beaches were probably due primarily to differences in sand temperatures,

though other environmental vicissitudes may also play a role. The

average incubation period of loggerhead clutches at Melbourne Beach

(53 days), was expected to be somewhat shorter than that reported for

South Carolina beaches (55 days, Caldwell, 1959a). The differences

noted between Melbourne Beach green turtle nests (54 days) and average

incubation periods from Costa Rica (62 days, Fowler, 1979) and Surinam

(58 days, Pritchard, 1969) were quite surprising. Both Costa Rica and

I ~~~Surinam lie in the tropics at latitudes 16 and 21 degrees south of

Melbourne Beach. During the summer solstice (21 June), however, Mel-

bourne Beach lies closer to the region of maximum solar intensity

3 ~~~(Tropic of Cancer) than Costa Rica or Surinam. A predominance of cloudy

or rainy days during the nesting season may also limit solar exposure on

these tropical beaches. Shading of nesting sites may dramatically

lengthen incubation times. Some of the green turtle nests in Fowler's

study were deposited in shaded areas and exhibited incubation periods as

long as 81 days. No such shaded sites were available for nesting

turtles at Melbourne Beach in 1985.

Nesting female size (CLSL) and clutch size of loggerheads nesting

on Melbourne Beach were very similar to those measures reported for

other nesting areas. Mean clutch size of Melbourne Beach loggerheads

(116 eggs) did not differ greatly from means reported for Cape Cana-

veral, Florida (110 eggs; Ehrhart, 1979), Little Cumberland Island,

Georgia (120 eggs; Richardson and Richardson, 1982), and Natal, South

Africa (117 eggs; Hughes, 1971). Mean CLSL of loggerheads nesting at

Melbourne beach (92.2 cm) did not differ significantly from measurements

made of loggerheads from Cape Canaveral (92.2 cm; Ehrhart, 1979) and

Natal (93 cm; Hughes, 1970).

There were significant disparities, however, between Melbourne

Beach green turtles and other populations, with respect to adult female

size and clutch size. Mean clutch size of Melbourne Beach green turtles

(145 eggs) differed significantly (students t-test, P < 0.05) from those

means reported from Tortuguero, Costa Rica (110 eggs) and Ascension

Island (116 eggs) by Carr and Hirth (1962); Sarawak (105 eggs; Hendrik-

son, 1958); Heron Island, Australia (110 eggs; Bustard, 1972); and

French Frigate Shoals, Hawaii (104 eggs; Balazs, 1980). Mean clutch

size of green turtles at Melbourne Beach was very similar, however, to

that reported by Pritchard (1969) for Surinam green turtles (142 eggs).

Oddly, mean clutch size differed significantly between Cape Canaveral

(130 eggs; Ehrhart, 1979) and Melbourne Beach green turtles. Both of

* ~~~~~~~~~~~~~83

these means for Florida green turtles, though, were significantly larger

than those of the aforementioned populations, except for Surinam green

* ~~~turtles.

Clutch sizes of Florida green turtles have been reported histori-

cally by Monroe (1898) to range from 130 to 180 eggs and by Audubon

(1926) to average about 140 eggs. Although these historical accounts

should be accepted cautiously, they do give some indications that

Florida green turtles have consistently exhibited large clutches.

3 ~~~Expressions of fecundity, like clutch size, may be controlled by both

genetic and environmental factors. This evidence, therefore, leads one

to believe that Florida's population of green turtles is at least

environmentally isolated, if not genetically distinct, from other

I ~~~Atlantic populations.

The selective advantage of large clutches is the obvious increase

in potential progeny. Environmental and physiological constraints,

3 ~~~however, ultimately dictate the upper limits of clutch size. Mortimer

(1981) suggested that sand grain size on the nesting beach may limit

clutch size by governing oxygen diffusion within the incubating clutch.

Mortimer speculated that larger sand grain size may facilitate a greater

rate of oxygen diffusion. Larger clutches require higher rates of

oxygen diffusion, due to the increased metabolic oxygen consumption of

more eggs and a lower surface area to volume ratio (Ackerman, 1977).

U ~~~Sands of Melbourne Beach are coarse grained with a significant biogenic

component consisting primarily of crushed shell. Considering the

success observed for green turtle nests within the study area, large

3 ~~~green turtle clutches fare quite well under Melbourne Beach's edaphic

conditions.

Mean size (CLSL) of green turtles nesting at Melbourne Beach

(101.5 cm) was found to be significantly larger (student's t-test,

P < 0.05) than that reported for French Frigate Shoals (92.2 cm; Balazs,

1980), but significantly smaller than means reported from Bigi Santi,

Surinam (111.8 cm; Pritchard, 1969) and Ascension Island (108.1 cm; Carr

and Hirth, 1962). Mean CLSL was found not to differ from means calcu-

lated for green turtles from Tortuguero (100.0 cm; Carr and Goodman,

1970) and Cape Canaveral (99.5; Ehrhart, 1979).

Size differences between Florida green turtles and other popula-

tions probably do not involve disparate age structures between the

populations. Such an argument is presented by Carr and Goodman (1970)

in which they speculate that mean size differences between populations

reflect, for the most part, differential sizes at which the animals

reach sexual maturity. Whether such disparities are governed by genetic

or environmental factors has yet to be determined.

A significant positive correlation was found between body size of

nesting loggerheads and green turtles, and their respective clutch sizes

(Figures 8 and 9, Tables 3 and 4). Hirth (1971) also reported that

larger green turtles deposited larger clutches. This phenomenon has

been reported, likewise, for other turtles such as Pseudemys scripta

(Gibbons, 1970), Chelydra serpentina {Yntema, 1970) and Sternotherus

odoratus (Tinkle, 1961). This reinforces the hypothesis that somatic

constraints are influential limitors of clutch size in turtles.

Loggerhead clutch sizes were found to be negatively correlated with

their respective dates of deposition (Table 3). Frazer and Richardson

(1985) found that for loggerheads nesting on Little Cumberland Island,

the number of eggs deposited in the final clutch of the season for the

* ~~~~~~~~~~~~~85

average nesting female was typically smaller, though not significantly

so. Smaller final clutches may manifest a trend toward smaller clutches

* ~~~later in the season and could explain the negative correlation between

season date and clutch size. To fully elucidate this phenomenon among

Melbourne Beach turtles, however, an analysis should concentrate on

monitoring successive clutches of individual turtles and not assessing

temporal trends of the population.

A significant negative correlation was found between the size of

* ~~~loggerhead nesting females and the date on which they nested (Table 3).

This correlation accompanies the general observation that larger turtles

were more common earlier in the season. Larger individuals may make the

extensive migration from the foraging grounds (Bahamas, Hispanola, Cuba;

Meylan et al., 1983) to the nesting beach in a shorter time than smaller

individuals. Such a size advantage in nesting migrations was proposed

by Carr and Goodman (1970) with respect to the arduous migrations of

Ascension Island green turtles. Given the relationship between body

size and clutch size, the arrival of smaller loggerheads later in the

season may contribute to the observed negative correlation between

clutch size and date.

Information on Movements of Nesting Females

Nesting site'philopatry and site fidelity are terms used by Carr et

al. (1978) in describing tendencies of marine turtles to nest faithfully

* ~~~on a single stretch of beach or closely situated beaches each year they

nest. These tendencies were investigated for Melbourne Beach logger-

heads, using information from 39 interseasonal recoveries of previously

tagged animals. These recoveries confirm earlier results of Bjorndal et

al. (1983), which indicated that Melbourne Beach loggerheads do not

display the type of religious site fidelity observed in green turtles

(Carr et al., 1978). Interseasonal recoveries of loggerheads on Mel-

bourne Beach (Appendix Table 7) were of turtles tagged as far away as

Georgia. Ten percent of these recoveries were from another major site

where nesting females are tagged, about 70 Ion north of the study area

(Cape Canaveral). Most of the remaining recoveries were from turtles3

tagged as they nested on Melbourne Beach during previous nesting sea-

sons. Two of these recoveries were from Loggerheads tagged on Melbourne

Reach 12 and 13 years prior to this study. These are among the longest

recovery intervals reported for nesting loggerheads.U

Intraseasonal recoveries of nesting loggerheads also showed logger-

heads to be less site tenacious than green turtles. The mean distance

between recoveries of nesting loggerheads within the 1985 season was3

about 4 km. Green turtles nesting at Tortuguero, Costa Rica are known

to regularly make successive nesting emergences within 200 m of previous

sites (Carr et al., 1978).

Of two green turtles that were observed on successive nestings at

Melbourne Beach, one nested within 50 m of its preceding nest, while the

other was observed nesting roughly 100 km to the south at Jupiter Island

(P.R. Witham, pers. comm.). The latter turtle may have been severely

frightened during a subsequent emergence, enough so to prompt an expan-

sive search for a more suitable nesting site. Behavior of this sort is

generally not seen in green turtles.3

Reproductive Success and Productivity

Measures and Comparisons

Most of the comparative analyses of reproductive success thus far

have excluded data from nests that were destroyed in the severe

* ~~~~~~~~~~~~~~87

September storm. Because destructive storms like this are relatively

uncommnon, an assessment excluding damage from storm provides a more

generalized baseline for comparisons. Throughout this section, unless

otherwise mentioned, measures of success are derived from non-storm

nests.

3 ~~~~Differences between hatching and emerging success were very small

for both species (Appendix tables 5 and 6). This indicates that the

vast majority of hatchlings that developed to term and pipped the egg,

3 ~~~emerged from the nest successfully. Likewise, mortality of hatchlings

en route from nest to surf was also found to be very small. The actual

rate of mortality for clutches emerging under conditions similar to

those at Melbourne Beach is probably also quite low.

Although actual hatchling production differed greatly between

loggerheads and green turtles, the average success of individual nests

was statistically similar. The actual hatchling production on Melbourne

Beach in 1985, including mortality from the September storm, was esti-

mated to be ca. 571,000 loggerhead and 21,000 green turtle hatchlings.

This extraordinarily high production may be much greater during a season

in which no major storms strike. Such a model year may see ca.' 751,000

loggerhead and 24,000 green turtle hatchlings leave the Melbourne Beach

study area. In all probability, this area produces more Florida green

turtle and loggerhead hatchlings than any comparable extent of Western

U ~~~Atlantic nesting beach.

Ideally, comparisons of reproductive success between nesting

beaches should be made with values averaged over a number of nesting

seasons. Unfortunately, very few of these assessments exist, let alone

any that include data for more than a single season. Reproductive

success on Melbourne Beach, or any other beach, undoubtedly varies among

years, depending primarily on major but infrequently random events such

as storms. Other major factors that influence mortality, including3

manmmalian predation, are probably expressed with relative consistency as

long as the environmental conditions of the beach remain somewhat

constant. Therefore, single-season assessments of success are probably

quite indicative of past and future success, as long as they do not

reflect catastrophic events. For purposes of this argument, their

comparative use is analytically worthwhile.

Various estimates and assessments of reproductive success on other

beaches exist in the literature. Estimates of emerging success based on

predation rates given in the literature were calculated, assuming that

non-depredated clutches were undisturbed and exhibited emergence succes-

ses similar to undisturbed Melbourne Beach nests. Error in these

estimates is probably positive.

Actual emerging success of loggerhead and green turtle nests at

Melbourne Beach, including nests destroyed by storms, was 52 and 511

percent in 1985. The same assessment of loggerhead and green turtle

emerging success, excluding storm-destroyed nests, was 64 and 59 per-

cent. Based on the reported percentage of clutches that emerged and the3

average success of emerged clutches, emerging success for loggerhead

nests at Cape Island, South Carolina in 1939 was about 32 percent

(Caldwell, 1959a). Hopkins et al. (1978) estimated this value at only 6

percent for the same beach in 1977, because of severe predation by

raccoons. Blanck and Sawyer (1979) estimated emerging success of

loggerhead nests at Ossabaw Island, South Carolina to be 0 percent,

again primarily due to raccoon predation. Raccoons have also beenI

* ~~~~~~~~~~~~~89

recognized as major success-limiting factors on Florida beaches. Based

on predation rates, emerging success of loggerhead nests was estimated

to be 0 to 15 percent on Cape Canaveral beaches (Ehrhart, 1976; Schroe-
der, 1981), about 30 to 40 percent at Hutchinson Island (Routa, 1967;

Gallagher et al. , 1972; Worth and Smith, 1976) and 5 to 27 percent on

I ~~~Cape Sable beaches (Davis and Whiting, 1977). Dogs (Canis) and coatis

(Nasua) were substantial predators of green turtle eggs in Fowler's

(1979) study in Costa Rica, where emerging success averaged 35 percent.

3 ~~~Ross and Barwani (1982) estimate emerging success of loggerhead nests to

average about 24 percent on the island of Masirah, where the surf is

reported to regularly take 40 percent of all deposited clutches.

Hobe Sound National Wildlife Refuge, Florida, apparently had rates

I ~~~of emerging success in 1985, comparable to those observed for Melbourne

Beach. Averaged estimates of loggerhead and green turtle emerging

success were 45 and 47 percent, including nests destroyed in the same

September storm that affected Melbourne Beach (Marcus, 1985). Part of

the high relative success of marine turtle nests on the Hobe Sound beach

can be attributed to raccoon control measures that were instated to

3 ~~~curtail predation of nests, which was historically quite extensive.

The rate of reproductive success of marine turtle nests at Mel-

bourne Beach appears to be relatively high. There are also indications

in the literature that past years may have been just as successful.

I ~~~Subjective reports of raccoon predation at Melbourne Beach (Bjorndal et

al., 1983; Raymond, 1984b) indicate that at least in the past ten years,

raccoon predation has been very low. Current levels of raccoon preda-

3 ~~~tion may, in fact, be elevated over historical ones, because of

increased raccoon densities. Raccoons are well-known human symbionts

an d may exist in greater numbers since the development of the barrier

island by humans. The original barrier island was a narrow strip of

xeric habitat with little fresh water and was probably capable of3

supporting only small densities of raccoons.

The only measured physical factor found to significantly affect

emerging success of sample nests was the vertical nest site choice of

the nesting loggerheads (tables 6a and 6b). Numbers of green turtle

nests deposited in the more seaward zones were too few to permit a

similar analysis for green turtles. Loggerhead nests in the center of

the berm fared best, while nests deposited lower on the beach were more
frequently destroyed by the surf, and nests deposited closer to the dune

were more frequently destroyed by predators and plant roots. It does

appear, therefore, that the vertical distribution of nest site choice of

nesting loggerheads correlates with reproductive success over the same

dimension.
Factors Affecting Reproductive Success

The following discussion addresses loggerhead and green turtle,

clutch and egg fates illustrated in figures 10 through 13 and tables 8

through 11.
Mortality Influenced by Numbers of Nesting Females-3

The destruction of incubating clutches by nesting females observed

at Melbourne Beach is probably closely tied to the number of nesting

females that use the beach. This type of mortality is thought to be

quite severe on the densely utilized loggerhead nesting beaches of

Masirah (Ross and Barwani, 1982) and Heron Island, Australia (Bustard,

1972). Although the level of this nest destruction is apparently quite

low at Melbourne Beach, nesting densities may have once been high enough

for such mortality to play a role in population regulation.

A form of mortality which may be indirectly linked to nesting

densities was the edaphic concentration of microbial pathogens. Mic-

robes were probably the primary cause of failure of eggs that displayed

addled contents or developmentally arrested embryos. Many of these egg

contents were stained pink from bacterial infections or had substantial

growth of fungi within the shell. Solomon and Baird (1979) report that

3 ~~~even undisturbed healthy eggs of marine turtles are prone to invasion by

fungal hyphae. Elevated levels of bacteria and fungi in the sand of

Melbourne Beach from heavy concentrations of rotting eggs from present

and past seasons, may make this a density-dependent phenomenon.

Damage related to sand accretion and surf -

Mortality of eggs due to the accretion of sand over loggerhead

nests was an unexpected phenomenon. The actual cause of failure of the

affected clutches was assumed to be suffocation. The eggs of clutches

destroyed in this manner were otherwise undisturbed, entire, and often

contained embryos whose development had been simultaneously arrested.

Ackerman (1977) has demonstrated that the depth and type of sand sur-

rounding marine turtle clutches greatly influences embryonic growth and

mortality. Sand that was accreted over nests due to storms was appar-

ently moved by wave action, not wind. In addition to changing the

3 ~~~quantity of sand over the clutch, this wave-deposited accretion may also

have changed the quality and arrangement of sand as well. Whether these

clutches were actually destroyed due to accretion of sand or were

3 ~~~affected by wave wash, is unknown. Green turtle clutches seem to have

avoided mortality from sand accretion, which for the most part, affected

a zone outside the one where green turtles most frequently nested.

Erosion and wave wash due to heavy surf conditions are known to3

exact heavy mortality on many nesting beaches (Mortimer, 1981; Ross and

Barwani, 1982; Small, 1982). Barring major storms, however, mortality

from erosion and inundation at Melbourne Beach was very low. Although

very few nests (especially those of green turtles) were deposited in the

zone of heaviest surf erosion, a number of nests received moderate,

periodic wave wash. McGehee (1979) suggested that this moderate wave

wash is relatively innocuous. The relatively high success of moderately3

wave-washed nests at Melbourne Beach tends to support this.

The primary cause of failure of clutches affected by surf condi-

tions was not drowning or dessication, but the partial exposure or total3

loss of a clutch due to erosion.

Damage due to storms -

The single, five-day northeaster storm that battered the study area

beach in mid-September was the principal cause of marine turtle clutchI

mortality in 1985. About 19 and 13 percent of all loggerhead and green

turtle nesting for the season was destroyed in this storm. Damage from

severe storms has the potential to be much higher, though there is a3

definite limit to the destruction a single storm can cause. An analy-

sis, based on the temporal distribution of loggerhead nesting at Mel-

bourne Beach, reveals that the greatest mortality caused by a single3

storm would be about 63 percent of all clutches. This would be the

case, providing the storm strikes about 22 July, when the greatest

number of loggerhead clutches are still incubating, and destroys all

incubating clutches. Such severe damage could only be administered by a3

I ~~~~~~~~~~~~~~93

major hurricane. Besides major hurricanes, the most destructive type of

storm to marine turtle clutches appears to be the lingering northeaster,

I ~~~such as the one that struck the study area in 1985. This storii was

observed to generate much more destructive erosion than the more violent

but fleeting tropical storms. The typical appearance of northeaster

3 ~~~storms in the autumn months may have been very influential in determin-

ing the period in which marine turtle nesting is most successful.

Raccoon predation-

The rate of raccoon predation on marine turtle clutches at Mel-

bourne Beach is quite low compared to other beaches in the southeast

United States, where the raccoon is the primary cause of clutch failure.

The proximity of Highway AIA to the study area beach is probably a

I ~~~significant factor in the reduction of raccoon population density there.

The highway mortality for four months within the twenty-one kilometers

surveyed was 25 raccoons, which was probably a substantial toll on the

* ~~~population.

The low rate of raccoon predation at Melbourne Beach may not be

entirely due to low raccoon population densities, though. Melbourne

Beach raccoons display a markedly naive approach to marine turtle nest

U ~~~predation. As an example, the raccoons at Melbourne Beach were almost

never known to depredate fresh nests. This is in striking contrast to

the raccoons of Cape Canaveral that excavate and destroy nearly every

3 ~~~clutch on the beach within hours of deposition (L. M. Ehrhart, pers.

comm.). It is likely that Melbourne Beach raccoons do not visually

recognize the disturbances left in the sand by nesting turtles as

potential sources of sustenance. Melbourne Beach raccoons appear to

locate clutches primarily by olfaction, deprediating only those clutches

that generate the wafting odor of pipping eggs during late incubation or

those clutches that have had eggs broken by invading ghost crabs. The

latter case explains the preponderance of clutches that were deprediated

during early and middle incubation, when all visual and olfactory

evidence would have normally been absent. Given the high percentage of

nests entered by ghost crabs, raccoons would have had ample oppor-

tunities to "follow their noses" down crab burrows to otherwise incon-

spicuous clutches.

In addition to the relative ineptitude of raccoons that did destroy

nests, the majority of raccoons at Melbourne Beach apparently did notI

depredate nests at all. A relative measure of raccoon population

density (road-kills) indicated that raccoons inhabited roughly the

entire study area. Predation of nests by raccoons, however, was largely

concentrated in only three of the twenty-one kilometers (Figure 16).

Most of the nest depredation at Melbourne Beach can probably be attrib-

uted to a small number of individual raccoons that have learned to

exploit turtle nests as a food source.

Raccoon predation of turtle nests was small enough, in relation to

sample size, to invalidate any statistical comparison between logger-

heads and green turtles. Subjectively, however, green turtle nestsI

appeared to be deprediated less often than loggerhead nests. The diffi-

culty in excavating the deeper clutches of green turtles may have

inhibited some raccoon predation.3

Ghost crab predation -

Although ghost crabs invaded a large percentage (about one third)

of all loggerhead and green turtle clutches, the total number of eggs

destroyed by ghost crabs was proportionately small (2 - 5%). Ghost

crabs were also found to be minor predators of eggs on South Carolina

beaches (Hopkins et al., 1978; Caldwell, 1959a) and at Tortuguero, Costa

Rica (Fowler, 1979). As an exception, Hill and Green (1971) found that

ghost crabs destroyed a fairly large percentage of green turtle eggs

(12%) on Bigi Santi Beach, Surinam.

Ghost crabs at Mvelbourne Beach were found to construct their

burrows with different frequencies in old nests, fresh nests and undis-

turbed beach (Table 13). Burrow site choice for ghost crabs is probably

linked closely to substrate friability. Ghost crabs were found to

burrow with greater frequency in moist, less friable sand, such as the

tilled substrate provided by fresh nests. Ghost crabs also appeared to

* ~~~prefer undisturbed beach over substrates made drier and more friable by

a weathered disturbance such as an old nest. This burrowing preference

held true for disturbances other than marine turtle nests. Based on

su bJective observations, Warner (1977) drew similar conclusions with

respect to ghost crab burrowing behavior.

It appears, therefore, that the discovery of marine turtle clutches

by ghost crabs is not a systematic search based on olfaction, but may

instead be a fortuitous windfall, owing to the selection of marine

turtle nests as preferential burrowing media. The stereotypic behavior

of a nesting marine turtle dispersing sand over her clutch could there-

fore be construed as being disadvantageous, if predation by ghost crabs

was a major selective agent. What this may tell us, however, is that

the evolutionary influence of ghost crab predation on the behavior of

nesting marine turtles was quite small. Nest obliteration behavior of

marine turtles is probably in response to the incomparably adverse

impact of mammalian predation.

Ghost crabs were found to be the primary predator of post-emergent

loggerhead hatchlings, though their contribution to overall mortality

was qu ite small. Predation of hatchlings by ghost crabs en route from

nest to surf is probably limited by the number of crabs in the vicinity

of the hatchling emergence which are robust enough to subdue a frenzied

hatchling. Whether green turtle hatchlings avoid predation by ghost3

crabs to some extent, by virtue of their slightly larger size, is

unclear.

Damage from plant roots-

The destruction of loggerhead and green turtle clutches by beachU

morning-glory and sea oat roots was a curious case of role reversal.

"Depredation" of marine turtle clutches by sea oats has also been

reported by Caldwell (1959a) and Raymond (1984b). Given the extent of

root growth and the pattern of mortality within the clutches involved,

it is reasonably certain that the penetration of eggs by the plant roots

was the primary cause of mortality and was not an incidental post-mortem

event.

The dune plants, apparently by design or by chance, exploit the

marine turtle clutches as moisture and nutrient sources. While this

relationship is assuredly beneficial to the plants and detrimental to

the turtle's clutch, it is not obvious whether the plants possess any

relevant adaptations besides the deep, rapidly growing root system that

is a standard attribute of dune plants.

Human induced mortality -

In general, beachfront residents and visitors to Melbourne Beach

were very protective of the marine turtles that nested on their beach.3

Mortality to eggs and hatchlings caused by humans was, for the most

I ~~~~~~~~~~~~~~97

part, incidental to non-malevolent actions. Despite these good inten-

3 ~~~tions, however, there were several moderate to severe impacts on marine

turtle reproductive success that resulted directly from turtle-human

cohabitation of the beach.

Poaching of marine turtle clutches was very infrequent, with only

I ~~~one case in over ten thousand nests recorded. The vigilance of beach-

front residents at Melbourne Beach was probably enough to discourage

most would-be poachers.

3 ~~~~A relatively severe impact on clutch survivorship was the frequent

deposition of sand and debris on the beach by property owners in

attempts to stabilize and rebuild their dune. Such construction prac-

p ~~~tices are prohibited without special permits from the Florida Department

of Natural Resources, permits which are not granted during the marine

turtle nesting season. In all cases the sand dumping activities were

completed within a single day, so that stopping them was, in effect, too

3 ~~~late to prevent the destruction of marine turtle clutches. Judging by

the quantities of sand and debris deposited on the beach and the densi-

ties of marine turtle nests involved, approximately one hundred clutches

may have been destroyed by these actions. It is clear that a more

rigorous enforcement of existing codes is needed on this valuable

stretch of marine turtle nesting beach.

By far, the most serious human-induced threat to marine turtle

I ~~~reproductive success currently manifesting itself on Melbourne Beach is

the disorientation of hatchlings by artificial beachfront lighting.

Hatchling disorientation from lights has also been judged a serious

3 ~~~threat on the densely-developed nesting beaches of southeastern Florida

(McFarlane, 1963; Mann, 1977). Mortality among disoriented clutches was

apparently very high. In addition to disorienting the nocturnal emer-

gences of hatchlings on the beach, artificial lights were also observed

to draw hatchlings from the surf that had already entered the ocean.3

This phenomenon has been similarly reported by Carr and Ogren (1960).

Such a strong affinity to lights must also cause hatchlings to linger in

the surf near brightly lighted areas. This would certainly increase the

rate of mortality from predatory surf zone fishes and draw from already

diminished energy resources needed by hatchlings for their upcoming

pelagic journey.

Artificial beachfront lighting generates many obviously detrimentalI

ramifications with respect to marine turtle reproductive success. Some

other impacts of a lighted beach may be just as, if not more serious,

but have yet to be identified. Considering the serious consequences,

beachfront lighting is certainly a conservation problem to be remedied.

An important step taken toward mitigating this problem was the passage

of an ordinance prohibiting beachfront lights within the unincorporateda

areas of Brevard County. This ordinance, which was passed prior to the

nesting season in 1985, was however, initially ineffective in darkening

the beach. Individual contacts with offending property owners were

needed to encourage the turning off of lights. Following this somewhatI

extensive effort, the beach became noticeably darker. The dramatic

decrease in the rate of disorientation on the darkened beach (Figure 18)

demonstrates that the problem of hatchling disorientation is certainly a

manageable one.

One human-induced threat to marine turtle reproductive success at

Melbourne Beach, of potentially great importance, is presently an

incipient one. The dune at Melbourne Beach is almost entirely in

private ownership and is currently being developed at an explosive rate.

One need only trace the history of privately owned beachfront property

in Florida to realize that the end result is one that is generally

unacceptable for the successful nesting of marine turtles. Although

very few beach-damaging seawalls and revetments presently exist at

Melbourne Beach, the forces of nature are irreversibly in progress that

will ultimately prompt their installation by worried condominium and

hotel owners, as properties continue to erode. An assessment of mea-

sures that could be taken to protect Melbourne Beach from this process

is greatly encouraged, but is beyond the scope of this report.

Offshore predation -

Surf zone and offshore predators of hatchlings obviously did not

affect the values reported for ocean-bound success. Their substantial

effect on overall hatchling recruitment, however, requires that some

analysis of the limited data be made. Interviews with resident surf

fisherman were made to acquire any evidence indicating predation of

hatchlings by fishes. The stomachs of 27 bluefish (Pomatomus

saltatrix), three red drum (Sciaenops ocellata) and one small blacktip

shark (Carcharhinus limbatus) were examined directly or vicariously

without discovering any hatchlings. Many of the fishermen interviewed

were convinced that red drum were the primary surf zone predator of

hatchlings, based on past evidence of hatchlings in their stomachs.

Some fishermen in fact, were certain that the fish congregated around

areas of the beach that produced large numbers of hatchlings. The catch

of red drum was very poor off and around Melbourne Beach in 1985.

Although the effect of surf zone fish predation on hatchling recruitment

is not quantified, the absence of such a major predator may have had

100

significant consequences with respect to the number of hatchlings

entering the pelagic environment.

The Importance of Melbourne Beach as a Marine Turtle Rookery3

This study has made it clear that, because of extraordinary levels

of nesting density and reproductive success, Melbourne Beach produces an

outstanding, perhaps unequaled, number of Florida green turtle and3

loggerhead hatchlings. It is clear that this beach is a vital source of

recruitment for these endangered populations. Our current paucity of

knowledge regarding population dynamics of marine turtles, however,

restricts our assessment of "adequate" and "inadequate" levels ofI

hatchling recruitment. In striving to conserve these species, there-

fore, a prudent course of action would be to mitigate factors that cause

excessive mortality to eggs and hatchlings on those beaches that have3

elevated potentials as hatchling producers (high density nesting

beaches).

The value of Melbourne Beach as a marine turtle rookery lies in the

fact that even without arduous and expensive management practices, it is

a very prolific producer of marine turtle hatchlings. This value

certainly entitles Melbourne Beach to the designation of "Critical

Habitat" proposed by Dodd in 1978. Regardless of the nomenclature,I

Melbourne Reach is in need of some protective, regulatory status; a

status that would incorporate measures to assure that Melbourne Beach

retains the attributes that justify the extensive and successful concen-5

tration of marine turtle reproductive effort there.

MANAGEMENT RECOMMENDATIONS

I ~~~~The following summaries of recommendations are deemed very impor-

tant to the conservation of Melbourne Beach's threatened and endangered

marine turtles.

1 ~~~1. Special Status - The Melbourne Beach area (Figure 1), or parts

thereof, should be given special status as a marine turtle sanctu-

ary. This auspice should incorporate protective guidelines that

* ~~~~would curtail detrimental and potentially detrimental activities

affecting this demonstrably important nesting beach. Designation

as Critical Habitat under the Endangered Species Act would be an

appropriate starting point.

1 ~~~2. 'Monitoring, - Monitoring on the nesting beach is very important if

deleterious impacts are to be recognized and acted on promptly.

Monitoring human activities such as vehicular traffic, dune resto-

ration, and beachfront lighting, coupled with subsequent mitigation

by the enforcement of already-existing codes, is the most cost-

effective and sensible method of bolstering reproductive success at

1 ~~~~Melbourne Beach. Other success-limiting factors, such as raccoon

predation, should also be monitored, so that informed decisions

concerning management can be made.

3. Management - Although reproductive success at Melbourne Beach is

3 ~~~~relatively high, substantial benefits are inherent in mitigating a

few readily accessible sources of mortality. No single source of

101

1021

mortality affected a large percentage of marine turtle clutches on

Melbourne Beach. Because of high nesting densities, however, even small

percentages of the nesting effort translate into large numbers of3

clutches. Removing a small number of raccoons from the limited area

affected by predation would save hundreds of loggerhead clutches.

Likewise, encouraging more residents to comply with the ordinance f

restricting beachfront lighting would save thousands of loggerhead

hatchl ings.

4. Regulation of Nearshore Activities - Because thousands of adult

turtles congregate in the waters off Melbourne beach during the

breeding season (April-August), any deleterious human activity or

influence in this region could have serious consequences. The

required use of the National Marine Fisheries Service's "TurtleI

Excluder Device" on shrimp trawlers operating off Melbourne Beach

is one example of an action that would mitigate mortality of adult

turtles. Further research may be needed to find ways to mitigateI

other human impacts such as dredging.

B. Research - Melbourne Beach's value as a productive marine turtle

rookery also makes it an important area for scientific research.

Marine turtle research is often limited by the availability ofI

animal subjects. This availability is much less restricted on

Melbourne Beach. In addition, information assimilated on such

characteristics as hatchling sex ratios, migratory patterns of

nesting adults and production, has broader applications with

respect to whole populations. For this reason, information

gathered at Melbourne Beach may better facilitate an understanding3

3 ~~~~~~~~~~~~~~103

of the Ilife histories and ecologic geographies of these

populations.

1 ~~~6. Public Education - Some effort should be made to enhance the

realization and appreciation of Melbourne Beach as an important

marine turtle rookery. Because any conservation initiative relies

3 ~~~~on public support, every effort should be made to make research

results available to clarify misconceptions about marine turtles

and to acquaint people with aspects of marine turtle biology and

3 ~~~~~conservation.

SUMMARY

A complete census of marine turtle nesting activity was undertaken3

within the 21 km Melbourne Beach study area in 1985. Loggerhead nesting

densities were found to average 490 nests per kilometer. Nesting of

this magnitude is apparently unequalled elsewhere in the Western Atlan-

tic. Nesting densities of Florida green turtles at Melbourne Beach

averaged 13.4 nests per kilometer. Though seemingly paltry in compari-

son to loggerhead nesting, this represented an over five-fold increase

in nesting over previous years and one of the densest recorded nestingI

concentrations from this endangered population. Only two leatherback

nests were deposited within the study area in 1985.

The presence of beachfront lights was found to correlate negativelyI

with areas of preferred green turtle nesting. Loggerheads were less

affected by this phenomenon but did appear to abandon nesting emergences

at a greater frequency in lighted areas. The spatial and temporal

distributions of nesting activity were found to differ between logger-I

heads and green turtles. These distributions were observed to vary in

accordance with the differential abilities of the two species to cope

with constraints imposed by nesting site/time choice.3

One hundred loggerhead, 27 green turtle, and 2 leatherback clutches

were monitored throughout their incubation. Significant correlations

were found between clutch sizes and the respective body sizes of nesting3

loggerheads and green turtles. Incubation period length was found not

104

3 ~~~~~~~~~~~~~~105

to vary significantly between loggerhead and green turtle clutches, nor

between three vertical zones in which the clutches were deposited.

I ~~~~Approximately 48 and 51 percent of the constituent eggs of logger-

head and green turtle nests at Melbourne Beach in 1985 resulted in

hatchlings that successfully entered the surf. These values of repro-

* ~~~ductive success were found to be very high when compared to data from

other nesting beaches. Ocean-bound success of loggerhead and green

turtle nests in a model year in which no major storms strike, is

expected to be approximately 63 and 58 percent. Success of loggerhead

nests was found to vary significantly between three vertical zones of

deposition. Success among loggerhead and green turtle nests was not

found to correlate with any other nest attribute.

I ~~~~The most damaging cause of mortality to clutches of both species

was a severe September northeaster storm. Raccoons and hatchling

disorientation by beachfront lights were also significant in limiting

3 ~~~reproductive success at Melbourne Beach. Predation of nests by raccoons

was restricted to a small portion of the study area and did not corre-

spond to areas of elevated raccoon population density. The rate of

hatchling disorientation was observed to decrease dramatically following

the enforcement of a regional ordinance prohibiting beachfront lighting.

High nesting densities and substantial success of deposited

clutches at Melbourne Beach accounted for the production of approxi-

3 ~~~mately 571,000 loggerhead and 21,000 Florida green turtle hatchlings in

1985.

I
APPENDIX

I
I

m- - - - - -m

Table 1. Morphological characteristics of nesting loggerhead turtles (Caretta caretta) encountered
during sample nest marking excursions on 21 km of beach in South Brevard County, Florida,
1985. Locations are specified as one km sections, the northernmost section (1) beginning
five km south of 5th Avenue, Indialantic, Florida.

Carapace Measurements (cm)
Straight Line Over Curvature Head
Sample Greatest Standard Width
Tag No. Nest No. Location Nesting Date Length Length Width Length Width (cm)

D3863 1 3 13-14 May 91.9 89.9 64.4 97.2 87.3 21.5
D3864 2 11 13-14 May 94.2 91.2 66.4 98.5 80.0 19.5
D3865 4 18 15-16 May 92.9 91.1 65.5 99.0 91.8 22.1
D3866 5 14 15-16 May 92.1 89.5 64.3 94.0 88.1 19.5
D3867 6 12 15-16 May 99.1 97.6 73.5 106.3 92.1 18.5

D3868 7 8 17-18 May 86.2 84.7 62.5 92.3 86.2 17.8 0
D3869 8 7 17-18 May 93.5 91.8 68.5 99.0 91.1 19.8
D3870 9 5 17-18 May 96.1 94.2 65.1 99.5 89.6 21.7
D3878 10 3 17-18 May 103.5 101.8 79.6 111.0 101.2 21.4
D3871 11 2 19-20 May 101.0 98.4 71.4 104.6 94.6 20.0

D3872 12 5 19-20 May 100.0 97.5 74.9 104.7 94.5 21.0
D3873 13 10 19-20 May 95.1 93.8 71.1 101.2 91.7 20.0
D3874 14 10 19-20 May 103.1 101.0 74.4 108.1 97.7 24.3
D3875 15 1 22-23 May 91.7 90.2 68.5 95.1 88.8 19.2
D3879 16 2 22-23 May 86.2 85.9 65.5 91.9 82.7 17.7
D3880 17 4 22-23 May 88.3 84.9 64.2 89.5 80.5 17.9

Table 1--continued.

Carapace Measurements (cm)
Straight Line Over Curvature Head
Sample Greatest Standard Width
Tag No. Nest No. Location Nesting Date Length Length Width Length Width (cm)

D3881 18 17 23-24 May 96.6 94.4 70.8 101.5 89.7 20.5
03882 19 16 23-24 May 102.0 99.5 78.6 105.4 97.0 21.8
D3883 20 14 23-24 May 95.4 93.2 69.3 98.3 90.2 21.1
D3884 21 12 23-24 May 95.7 95.0 65.2 101.6 86.8 20.5
B3576 -- 11 26-27 May -- 92.7 69.5 99.8 -- --

D3885 22 11 26-27 May 98.0 94.2 76.2 99.0 94.6 19.2
D3887 23 12 26-27 May 91.1 90.2 66.5 95.7 88.8 18.8
D3888 24 13 26-27 May 91.6 89.1 70.6 94.8 94.0 19.9
03889 25 21 26-27 May 98.5 96.5 67.9 101.8 90.4 21.0
D3890 26 18 26-27 May 90.1 88.7 67.7 94.2 86.7 18.0

D3895 -- 10 29-30 May -- 93.0 70.6 100.5 94.0 --
D3896 27 9 29-30 May 100.2 98.7 75.6 105.6 97.4 21.0
D3897 28 9 29-30 May 94.4 92.8 75.5 99.3 91.6 21.0
D3898 -- 10 29-30 May -- 95.0 -- 99.8 -- --
D3899 29 14 29-30 May 100.3 97.8 73.0 103.0 95.6 20.7
T2318 -- 13 29-30 May -- 94.0 -- 103.3 -- --

m m _ m m m

Table 1--continued.

Carapace Measurements (cm)
Straight Line Over Curvature Head
Sample Greatest Standard Width
Tag No. Nest No. Location Nesting Date Length Length Width Length Width (cm)

D3900 30 13 31-1 June 99.4 98.1 73.0 106.3 95.7 22.4
D4001 31 14 31-1 June 103.8 100.1 73.0 107.8 99.0 21.6
D4002 32 11 31-1 June 103.2 101.4 69.0 108.3 94.2 24.0
D4003 -- 10 31-1 June 95.0 94.0 71.7 100.0 91.8 19.0
SI423 -- 6 31-1 June 90.7 90.1 65.6 96.7 87.2 19.0

D4004 -- 5 31-1 June 97.6 94.9 71.1 100.0 97.7 21.1
D4005 33 15 2-3 June 87.7 87.3 64.4 94.9 67.0 19.0
D4006 34 16 2-3 June 97.6 95.0 76.6 102.5 92.8 22.6
D4007 35 17 2-3 June 92.0 90.8 64.0 95.9 84.3 18.8
D4008 36 18 2-3 June 94.6 92.8 66.9 97.3 90.7 23.4

D4009 37 1 2-3 June 96.8 94.9 72.0 101.8 92.8 19.9
D4010 38 11 5-6 June 101.4 99.9 73.8 108.9 97.9 20.3
D4011 39 10 5-6 June 94.1 91.8 74.0 98.0 92.9 18.0
D4012 41 16 9-10 June 95.5 93.1 70.7 101.4 90.8 17.4
D4013 42 12 9-10 June 99.1 96.8 75.6 104.8 97.7 20.1
D4014 43 16 9-10 June 102.8 100.1 79.1 108.2 99.5 20.7

Table 1--continued.

Carapace Measurements (cm)
Straight Line Over Curvature Head
Sample Greatest Standard Width
Tag No. Nest No. Location Nesting Date Length Length Width Length Width (cm)

D4015 44 17 9-10 June 90.9 90.3 68.0 96.6 89.3 19.5
D4016 46 9 12-13 June 95.0 92.9 71.2 100.5 95.5 20.5
SI12239 -- 1 17-18 June -- -- -- 91.8 79.2 --
04017 47 2 17-18 June 92.9 91.1 67.1 96.8 84.9 18.9
D4018 48 3 17-18 June 82.5 80.9 58.3 87.9 84.0 16.8

D4019 49 7 17-18 June 91.9 91.0 72.0 96.3 87.2 19.9
D4020 50 5 17-18 June 91.2 89.8 69.9 96.2 92.2 18.2
D4021 51 2 17-18 June 94.2 93.7 69.1 104.0 92.4 19.0
D4022 53 3 20-21 June 91.4 90.9 67.5 97.5 88.1 17.9
D4023 -- 5 20-21 June 95.5 95.2 75.2 100.7 98.8 21.7

D4025 54 3 20-21 June 92.5 91.6 70.5 97.8 90.2 20.2
D4026 -- 20 23-24 June 96.0 95.6 66.0 102.3 90.1 20.2
03112 -- 19 23-24 June -- 91.7 65.5 97.5 87.0 19.5
04028 55 18 23-24 June 92.4 91.1 69.7 99.0 91.5 19.0
D4032 56 11 24-25 June 86.6 84.8 62.0 92.0 82.1 16.9
D4031 57 11 24-25 June 95.1 92.5 74.9 99.5 93.9 20.9

m m m m -

Table 1--continued.

Carapace Measurements (cm)
Straight Line Over Curvature Head
Sample Greatest Standard Width
Tag No. Nest No. Location Nesting Date Length Length Width Length Width (cm)

D4035 58 17 24-25 June 84.4 83.7 64.0 90.0 84.1 17.1
D4027 61 18 24-25 June 85.4 84.0 64.3 92.1 82.6 17.9
D4034 62 15 24-25 June 104.4 101.3 80.7 102.0 110.4 20.8
D4030 52 18 26-27 June 90.0 88.8 69.9 94.7 88.5 18.2
D4029 64 17 26-27 June 88.1 87.3 61.9 94.4 87.4 18.0

D3891 68 17 26-27 June 88.5 88.0 65.0 94.0 85.3 17.9
D4037 65 20 30-1 July 92.5 92.2 68.6 96.0 89.5 19.5
D4038 67 17 30-1 July 94.4 92.6 65.2 99.4 67.3 20.5
D4039 69 15 30-1 July 97.8 97.1 75.0 91.8 103.5 20.7
D4040 70 13 30-1 July 91.9 90.5 70.7 95.3 89.2 20.1

D4041 71 7 1-2 July 102.9 101.9 77.3 111.0 101.4 20.7
D4042 72 6 1-2 July 91.1 89.1 68.6 95.1 89.4 18.5
D4043 -- 6 1-2 July 87.0 85.9 67.4 93.6 84.3 19.5
D4044 73 6 1-2 July 90.7 88.8 72.3 95.9 88.6 18.0
D4045 74 3 1-2 July 99.1 98.1 76.6 105.6 101.4 23.6
D4046 75 6 1-2 July 91.5 89.2 69.9 95.2 86.0 19.1

Table 1--continued.

Carapace Measurements (cm)
Straight Line Over Curvature Head
Sample Greatest Standard Width
Tag No. Nest No. Location Nesting Date Length Length Width Length Width (cm)

D4049 82 14 7-8 July 98.9 97.8 72.3 107.0 100.0 21.5
D4053 84 14 7-8 July 92.0 89.6 70.2 98.6 91.3 18.5
D4055 85 17 9-10 July 90.3 88.3 69.8 95.1 89.9 19.1
D4054 86 18 9-10 July 98.4 96.8 68.6 102.7 94.2 20.3
D4056 87 15 9-10 July 85.8 84.4 64.9 92.0 86.4 18.4

D4057 88 11 10-11 July 95.5 93.9 75.9 100.0 96.7 20.8
D4058 89 9 10-11 July 101.1 98.8 75.3 106.0 101.9 20.5
D4059 90 4 10-11 July 86.1 84.3 67.2 89.5 90.0 16.7
*D3869 91 6 10-11 July 93.5 91.8 68.5 99.0 91.1 19.8
C2003 -- 6 10-11 July 98.7 97.4 74.0 108.5 98.5 21.0

T2088 -- 13 15-16 July 95.5 94.3 68.9 103.2 91.3 20.5
D4065 93 11 15-16 July 99.3 97.7 73.8 105.5 92.5 20.9
04063 94 9 15-16 July 98.9 96.5 72.0 104.1 91.0 19.2
D4060 95 9 15-16 July 93.3 91.5 69.2 99.0 88.5 18.0
T2201 -- 2 17-18 July 92.0 90.5 67.4 95.0 88.0 21.2
D4076 96 6 17-18 July 94.5 92.1 69.5 98.0 90.9 18.6

_m m m m m__

- - m - - m m

Table 1--continued.

Carapace Measurements (cm)
Straight Line Over Curvature Head
Sample Greatest Standard Width
Tag No. Nest No. Location Nesting Date Length Length Width Length Width (cm)

D4077 98 3 17-18 July 97.7 95.5 68.7 103.0 92.8 19.8
D4085 102 10 22-23 July 97.5 94.0 78.1 100.3 100.1 18.7
D4075 106 10 22-23 July 93.9 92.4 70.0 97.5 89.3 18.3
D4074 107 8 22-23 July 85.9 85.4 68.1 94.0 88.1 17.0
D4091 -- 14 22-23 July 90.4 89.0 67.3 95.5 88.8 17.9

D4092 -- 1 24-25 July 91.8 90.0 72.5 96.9 89.2 18.8
D4093 -- 2 24-25 July 90.4 88.3 73.1 -- -- 19.3
H1955 -- 8 26-27 July 99.9 97.8 70.7 104.7 92.9 21.9
04072 115 8 29-30 July 98.9 94.6 75.0 101.8 91.5 21.7
D4086 116 4 29-30 July 94.2 92.2 81.3 102.1 95.0 19.5

D4073 117 10 29-30 July 90.5 89.5 69.3 97.2 91.0 18.2
D4098 119 11 29-30 July 93.1 91.9 70.9 99.6 88.5 18.8
D4062 120 19 29-30 July 91.7 89.7 65.8 98.4 88.9 18.1
*D4030 121 13 29-30 July 90.1 88.6 69.8 94.5 88.5 18.0
D4099 122 19 29-30 July 88.2 86.7 72.0 92.7 89.7 17.0

Table 1--continued.

Carapace Measurements (cm)
Straight Line Over Curvature Head
Sample Greatest Standard Width
Tag No. Nest No. Location Nesting Date Length Length Width Length Width (cm)
D4050 123 17 29-30 July 92.1 89.3 65.8 95.9 83.2 18.3
SI3348 -- 17 30-31 July 86.3 82.2 60.8 90.5 83.9 16.1
D4112 118 13 31-1 August 88.1 87.2 62.4 95.9 83.1 17.3
*D4008 124 17 31-1 August 94.6 92.8 66.9 97.3 90.7 23.4
D4107 127 11 1-2 August 91.2 88.3 64.5 96.3 72.1 19.5

D4116 -- 12 11-12 August 88.1 85.8 61.9 92.5 83.0 17.5
D4117 129 9 11-12 August 91.3 89.5 69.6 92.8 84.4 18.7
D4118 -- 8 11-12 August 93.6 91.3 70.9 96.0 89.8 19.5
D4100 130 5 11-12 August 86.2 85.7 63.7 94.3 78.5 16.1
D4097 128 10 14-15 August 89.4 88.4 67.5 95.1 85.3 18.0

D4119 132 6 14-15 August 99.6 96.9 73.5 104.6 91.5 21.1
D4120 -- 12 29-30 August 91.0 89.3 68.8 96.6 88.1 17.3

N 114 119 117 119 116 115
x 93.9 92.2 69.8 98.9 90.3 19.6
SD 4.93 4.63 4.56 5.04 6.54 1.68
Range 82.5- 80.9- 58.3- 87.9- 67.0- 16.1-
104.4 101.9 81.3 108.9 110.4 24.3

*Turtle encountered and measured previously this season. Only initial measurements used in calcu-
lating means.

m_ -

m MM m m - m m

Table 2. Morphological characteristics of nesting green turtles (Chelonia Mydas) encountered
during sample nest marking excursions on 21 km of beach in South Brevard County, Florida,
1985. Locations are specified as one km sections, the northernmost section (1) beginning
five km south of 5th Avenue, Indialantic, Florida.

Carapace Measurements (cm)
Straight Line Over Curvature Head
Sample Greatest Standard Width
Tag No. Nest No. Location Nesting Date Length Length Width Length Width (cm)

-- -- 11-20 August 1985 -- 102.8 74.2 109.0 97.0 13.4
-- -- 11-20 August 1985 -- 103.5 81.5 109.5 107.0 14.5
-- -- 11-20 August 1985 -- 103.5 81.2 108.8 102.0 14.2
D4024 -- 15 23-24 June 102.3 101.2 83.1 107.6 104.2 15.0
D4033 63 16 24-25 June 99.7 99.4 78.0 106.5 94.2 13.1
D4036 66 16 26-27 June 108.0 107.1 82.9 112.1 103.8 14.3
SI2970 81 8 6-7 July -- -- -- 116.0 100.0 14.0
04051
D4052 83 14 7-8 July 98.8 95.7 77.9 102.9 97.2 13.9
D4052
D3893 -- 18 10-11 July 103.2 103.0 77.2 108.8 96.3 14.1
D4066 97 12 15-16 July 113.0 112.5 88.8 120.2 110.9 14.9
D4061
D4067 103 15 17-18 July 101.3 101.3 78.9 108.2 100.5 13.1
D4067

D4068 104 15 17-18 July 104.2 104.0 82.4 110.0 109.8 13.2
04069

D4070 105 14 17-18 July 106.8 106.0 82.0 111.5 102.1 14.8
D4071

4078 100 2 17-18 July 102.6 101.9 79.1 108.3 96.8 13.5
04079

Table 2--continued

Carapace Measurements (cm)
Straight Line Over Curvature Head
Sample Greatest Standard Width
Tag No. Nest No. Location Nesting Date Length Length Width Length Width (cm)

D4080 99 2 17-18 July 102.7 101.7 83.4 109.1 106.2 14.2
D4081
D4082
D4083 101 1 17-18 July 101.5 101.0 75.1 106.9 99.8 14.3
AAV046 108 20 21-22 July 99.2 99.0 74.5 102.4 92.3 18.2
SI3098 -- 19 21-22 July -- 107.2 74.8 108.7 96.6 13.8
04086
SI43096 109 15 22-23 July 100.4 99.3 73.4 105.7 92.8 14.0
04089
D4090 111 18 22-23 July 103.4 103.5 81.2 110.2 105.2 14.1
D4090
03894 -- 16 24-25 July 100.7 98.7 79.5, 106.3 105.2 13.7
*D4036 114 16 25-26 July 108.2 107.5 82.1 112.9 102.3 14.7
04047
D4048 112 16 25-26 July 97.0 95.6 75.8 102.0 93.6 12.5
**D4084 -- 13 25-26 July 86.9 83.2 67.0 97.0 94.2 13.0
D4094 -- 9 26-27 July 114.0 113.5 87.3 121.2 110.1 14.3

*Turtle encountered and measured previously this season. Only initial measurements used in
calculating means.
**Turtle prominently kyphotic (see text).

Table 2--continued

Carapace Measurements (cm)
Straight Line Over Curvature Head
Sample Greatest Standard Width
Tag No. Nest No. Location Nesting Date Length Length Width Length Width (cm)

D4095
D4096 113 5 26-27 July 100.1 99.8 78.2 106.8 96.0 13.5
D4096
D4114 126 9 1-2 August 101.0 98.8 78.2 106.3 96.6 14.7
D4102 125 10 5-6 August 102.0 101.6 81.6 111.0 106.0 13.6
D4105 -- 7 11-12 August 96.7 96.5 77.5 102.8 95.9 13.1

N 23 27 27 28 28 28
x 102.0 101.5 79.1 108.4 100.4 14.0
SD 5.42 5.66 4.52 5.07 5.60 1.03
Range 86.9- 83.2- 67.0- 97.0- 92.3- 12.5-
114.0 113.5 88.8 121.2 110.9 18.2

Table 3. Characteristics of loggerhead (Caretta caretta) sample nests
marked during the 1985 nesting season in south Brevard County,
Florida. Definitions for incubation period, zone of deposi-
tion, and emerging success are given in the report text.
Disturbances are symbolized as follows: C, ghost crab pre-
dation; R, raccoon predation; P, plant root Infiltration; T,
major tidal inundation; S, major sand accretion.

Deposition Incubation Zone of Emerging
Nest No. Date(1985) Period (days) Deposition Success(%) Disturbance
1 13-14 May 56 B 97.2 none
2 13-14 May 57 B 63.9 C
4 15-16 May 53 B 69.8 C
5 15-16 May -- B 0 none
6 15-16 May 54 B 68.7 C
7 17-18 May 54 B 98.1 none
8 17-18 May 54 B 80.0 C
9 17-18 May -- B 0 none
10 17-18 May 54 B 84.2 C
11 19-20 May 53 C 6.1 R
12 19-20 May 57 B 86.1 C
13 19-20 May 54 B 81.5 none
14 19-20 May 55 A 61.9 C
15 22-23 May 58 B 91.3 none
16 22-23 May -- B 0 R
17 22-23 May 53 B 61.2 none
18 23-24 May 53.5 B 12.9 P
19 23-24 May 54 A 0.7 P
20 23-24 May 52.5 B 91.4 none
21 23-24 May 54 B 95.4 none
22 26-27 May 53.5 C 98.0 none
23 26-27 May 55 B 90.1 none
24 26-27 May 51 B 96.1 none
25 26-27 May 55 A 74.8 none
26 26-27 May 51 B 88.4 none
27 29-30 May -- C 77.5 C

119

Table 3--continued

Deposition Incubation Zone of Emerging
Nest No. Date(1985) Period (days) Deposition Success(%) Disturbance
28 29-30 May 50 A 93.1 none
29 29-30 May 52 B 96.5 none
30 31-1 June 56 C 95.0 none
31 31-1 June 52 B 78.2 C
32 31-1 June 52 B 87.7 C
33 2-3 June 51 C 81.3 C
34 2-3 June 50 A 83.1 C
35 2-3 June 50 A 99.1 none
36 2-3 June 54 B 76.5 C
37 2-3 June 57 A 68.8 none
38 5-6 June 55 A 94.1 none
39 5-6 June 56 B 54.0 none
41 9-10 June -- C 22.6 C
42 9-10 June 55 B 81.9 C
43 9-10 June 52 B 67.4 none
44 9-10 June 54 A 17.0 P
46 12-13 June -- C 0 T
47 17-18 June 54 C 4.8 C
48 17-18 June 54 C 93.4 none
49 17-18 June 52.5 B 97.3 none
50 17-18 June C 0 T
51 17-18 June 50 A 57.3 C
53 20-21 June 53.5 C 84.5 none
54 20-21 June 53 C 88.0 none
55 23-24 June -- C 0 S
56 24-25 June -- C 0 T
57 24-25 June 53 B 88.1 C
58 24-25 June 51 C 86.8 C
61 24-25 June -- B 0 R
62 24-25 June 53 C 80.9 none

120

Table 3--continued

Deposition Incubation Zone of Emerging
Nest No. Date(1985) Period (days) Deposition Success(X) Disturbance
64 26-27 June 49 B 88.2 C
68 26-27 June 51 B 32.9 none
52 26-27 June -- C 0 S
65 30-1 July -- A 0 R
67 30-1 July -- A 0 R
69 30-1 July 51 A 76.0 C
70 30-1 July 52 B 27.7 C
71 1-2 July 51 B 95.6 none
72 1-2 July 52 B 97.9 none
73 1-2 July -- C 79.6 none
74 1-2 July 55 C 84.2 none
75 1-2 July 52 B 88.9 none
82 7-8 July 54 C 97.7 none
84 7-8 July 55 C 94.7 none
85 9-10 July -- C 0 R
86 9-10 July -- C 0 R
87 9-10 July 57 C 96.0 none
88 10-11 July 53 B 87.9 none
89 10-11 July 51 B 53.1 C
90 10-11 July 52 B 91.2 none
91 10-11 July 51.5 B 97.7 none
93 15-16 July 51.5 B 82.9 none
94 15-16 July 51 B 62.8 C
95 15-16 July 54 C 39.4 C
96 17-18 July 51 B 96.3 none
98 17-18 July 52 A 64.6 C
102 22-23 July -- C -- --
106 22-23 July -- C -- --
107 22-23 July -- B 95.2 none
115 29-30 July -- C 0 T

121

Table 3--continued

Deposition Incubation Zone of Emerging
Nest No. Date(1985) Period (days) Deposition Success(%) Disturbance
116 29-30 July -- C 0 T
117 29-30 July -- C 0 T
119 29-30 July -- C 0 T
120 29-30 July -- B 0 T
121 29-30 July -- C 0 T
122 29-30 July 53 B 71.9 none
123 29-30 July -- B 0 T
118 31-1 Aug. -- B 44.3 C
124 31-1 Aug. -- B 0 T
127 1-2 Aug. -- A -- --
129 11-12 Aug. -- B 0 S
130 11-12 Aug. -- B 0 S
128 14-15 Aug. -- C 0 T
132 14-15 Aug. -- A 0 S

3 x 52.7 -- 52.7
Zone A SD 2.53 -- 38.0
n 12 16 15

x 53.0 -- 64.7
Zone B SD 1.94 -- 35.5
n 40 51 51

x 53.8 -- 42.3
Zone C SD 1.60 -- 43.5
n 15 33 31

x 53.1 -- 55.7
Total SD 1.99 -- 39.5
n 67 100 97

122 3

Table 4. Characteristics of green turtle (Chelonia mydas) sample nests
marked during the 1985 nesting season in south Brevard County,
Florida. Definitions for incubation period and zone of
deposition are given in the report text. Disturbances are
symbolized as follows: C, ghost crab predation; R, raccoon
predation; P, plant root infiltration; T, major tidal inunda-
tion; B, emergence blocked (see text).

Deposition Incubation Zone of
Nest No. Date (1985) Period (days) Deposition Disturbance
40 5-6 June 56 B C
59 19-20 June 51 A none
63 24-25 June -- C T
66 26-27 June 53 A B
76 1-2 July 51 A C
77 2-3 July 54 A none
78 2-3 July -- A R
79 4-5 July 51 A none
80 5-6 July 52 A C
81 6-7 July -- A P
83 7-8 July 53 B C
92 12-13 July 54.5 A C
97 15-16 July 56 C none
99 17-18 July 54 A none
100 17-18 July 55.5 A none
101 17-18 July 54 A P
103 17-18 July 54 A P
104 17-18 July 56 A none
105 17-18 July 54 B none
108 21-22 July 52 A none
109 22-23 July -- A none
111 22-23 July 65 A none
112 25-26 July -- A C

123

Table 4--continued

Deposition Incubation Zone of
Nest No. Date (1985) Period (days) Deposition Disturbance
114 25-26 July 49 A none
113 26-27 July 56 B T
126 1-2 August -- A --
125 5-6 August -- A --

Zone A n -- 21 --
Zone B n -- 4 --
Zone C n -- 2 --

x 54.1 --.
Total SD 3.26 .
n 20 .

124

Table 5. Clutch size and three measures of nest success for loggerhead
(Caretta caretta) sample nests marked during the 1985 nesting
season in south Brevard County, Florida. Definitions of the
three measures of nest success are given in the report text.

Hatching Emerging Approximate
Nest No. Clutch Size Success(%) Success(%) Ocean-Bound Success(%)
1 109 97.2 97.2 80.0
2 118 63.9 63.9 63.9
4 126 70.6 69.8 69.8
5 111 0 0 0
6 131 68.7 68.7 68.7
7 107 98.1 98.1 98.1
8 120 82.5 80.0 72.0
9 104 0 0 0
10 139 88.5 84.2 84.2
11 131 87.8 6.1 6.1
12 144 86.1 86.1 86.1
13 130 82.3 81.5 81.5
14 134 61.9 61.9 61.9
15 104 91.3 91.3 --
16 93 0 0 0
17 116 61.2 61.2 58.6
18 101 13.9 12.9 --
19 143 0.7 0.7 0.7
20 128 91.4 91.4 --
21 132 95.4 95.4 94.7
22 133 98.0 98.0 --
23 132 93.9 90.1 90.1
24 129 96.9 96.1 93.8
25 135 74.8 74.8 74.8
26 121 88.4 88.4 --
27 151 77.5 77.5 --
28 116 93.1 93.1 93.1

125

Table 5--continued

Hatching Emerging Approximate
Nest No. Clutch Size Success(%) Success(%) Ocean-Bound Success(%)
29 143 97.2 96.5 96.5
30 119 97.5 95.0 92.4
31 165 79.4 78.2 78.2
32 163 90.8 87.7 --
33 112 81.3 81.3 --
34 124 83.1 83.1 83.1
35 109 99.1 99.1 99.1
36 136 91.9 76.5 76.5
37 141 77.3 68.8 --
38 118 94.9 94.1 86.4
39 126 54.0 54.0 54.0
41 106 22.6 22.6 --
42 127 85.8 81.9 81.1
43 132 68.9 67.4 67.4
44 112 17.9 17.0 17.0
46 135 0 0 0
47 103 4.8 4.8 4.8
48 76 94.7 93.4 88.2
49 110 97.3 97.3 --
50 102 0 0 0
51 117 59.0 57.3 --
52 121 0 0 0
53 103 87.4 84.5 --
54 108 88.0 88.0 --
55 91 0 0 0
56 91 0 0 0
57 118 89.0 88.1 --
58 106 86.8 86.8 86.8
61 126 0 0 0
62 157 80.9 80.9

126

Table 5--continued

Hatching Emerging Approximate
Nest No. Clutch Size Success(%X) Success(%) Ocean-Bound Success(%)
64 70 32.9 32.9 32.9
65 109 0 0 0
67 93 0 0 0
68 102 94.1 88.2 87.2
69 125 77.6 76.0 76.0
70 94 27.7 27.7 27.7
71 135 95.6 95.6 --
72 96 97.9 97.9 97.9
73 98 79.6 79.6 --
74 146 84.9 84.2 --
75 90 90.0 88.9 86.7
82 129 99.2 97.7 --
84 95 94.7 94.7 --
85 101 0 0 0
86 117 0 0 0
87 99 96.0 96.0 96.0
88 116 90.5 87.9 87.9
89 128 53.9 53.1 --
90 102 91.2 91.2 90.2
91 87 100.0 97.7 --
93 129 90.7 82.9 --
94 129 62.8 62.8 62.0
95 109 41.3 39.4 39.4
96 108 96.3 96.3 95.4
98 113 64.6 64.6 63.7
102 127 -- --
106 121 -- -- --
107 83 95.2 95.2 --
115 149 0 0 0
116 136 0 0 0 0

127

Table 5--continued

Hatching Emerging Approximate
Nest No. Clutch Size Success(%) Success(%) Ocean-Bound Success(%)
117 96 0 0 0
118 97 46.4 44.3 --
119 110 0 0 0
120 102 0 0 0
121 119 0 0 0
122 96 72.9 71.9 --
123 86 0 0 0
124 114 0 0 0
127 107 -- -- --
128 92 0 0 0
129 114 0 0 0
130 92 0 0 0
132 124 0 0 0
UNDISTURBED NESTS
x 83.9 82.9
SD 23.1 23.0
n 43 43
NESTS NOT AFFECTED BY SEPTEMBER STORM
x 65.7 63.6 55.7
SD 36.2 36.2 38.1
n 85 85 58

TOTAL NESTS
x 116 57.4 55.7 46.2
SD 18.8 39.9 39.5 40.6
n 100 97 97 70

128

Table 6. Clutch size and three measures of nest success for green
turtle (Chelonia mydas) sample nests marked during the 1985
nesting season in south Brevard County, Florida. Definitions
of the three measures of nest success are given in the report
text.

Hatching Emerging Approximate
Nest No. Clutch Size Success(%) Success(%) Ocean-Bound Success(%)
40 129 83.7 82.2 82.2
59 167 74.2 74.2 --
63 142 0 0 0
66 150 92.0 0 0
76 158 81.6 81.0 --
77 138 90.6 88.4 88.4
78 131 0 0 0
79 172 76.2 75.0 75.0
80 150 62.7 61.3
81 146 1.4 0 0
83 140 90.7 90.7 90.7
92 155 80.0 80.0 --
97 193 91.2 91.2
99 142 81.7 80.3 --
100 126 72.2 71.4 --
101 143 54.5 54.5 52.4
103 179 51.9 50.3
104 134 85.1 84.3 84.3
105 156 13.5 13.5 13.5
108 138 94.9 94.2 94.2
109 130 80.0 80.0 --
111 60* 83.3 81.7 --
112 102 0 0 0
113 155 20.0 3.2 3.2
114 152 78.9 78.3 78.3
125 179 -- -- --
126 169 -- -- --

129

Table 6--continued

Hatching Emerging Approximate
Nest No. Clutch Size Success(M) Success(M) Ocean-Bound Success(%)
UNDISTURBED NESTS
i 78.0 76
SD 20.7 20.9
n 13 12

NESTS NOT AFFECTED BY SEPTEMBER STORM
xi 63.3 58.8 47.1
SD 33.5 35.0 41.5
n 24 24 14

TOTAL NESTS
Ux 149 61.6 56.6 44.1
SD 19.7 33.9 36.1 41.6
n 26 25 25 15

* clutch size not used in calculation of mean (see text)

130

Table 7. Information from recoveries of previously tagged loggerheads
(Caretta caretta) observed on 21 km of beach in south Brevard
County, Florida, 1985. Abbreviations: MB, Melbourne Beach
(present study area); SI immediately south of Sebastian Inlet,
Florida; KSC, Kennedy Space Center beach, Florida; CNS,
Canaveral National Seashore, Florida; GA, Cumberland Island,
Georgia.

Straight Line
Tag No. Original Time Carapace Growth (cm)
Recent Original Location Elapsed (yr) Width Length

D3866 G1206 MB 8 -- -
D3869 T2872 MB 3 1.7 -0.8
-- T2898 MB 3 -- --
-- SI2334 MB 2 -- --
D3880 D3180 MB 3 -0.8 1.1
-- B3576 MB 8 0.9 -1.3
D3887 D3512 MB 3 -- -
03895 16248 MB 4 2.4 1.9
D3898 P1199 KSC 6 -- 0.1
- T2318 MB 3 -- -0.2
D4002 D3146 MB 3 2.3 0.6
D4003 SI2110 MB 2 -- --
-- SI423 SI 10 -- --
D4004 D3256 MB 3 -0.9 0.1
D4007 D3336 MB 3 2.5 2.4
-- T2716 MB 3 -- -
-- D3258 MB 3 -- _
-- SI2239 MB 2 -- --
D4023 G1306 MB 6 -1.0 2.5
D4026 C1640 MB 13 -- --
-- D3112 MB 3 -0.3 0.5
D4040 H3134 KSC 6 0.2 1.0
D4043 D3213 MB 3 0.8 0.9

Table 7--continued

Straight Line
Tag No. Original Time Carapace Growth (cm)
Recent Original Location Elapsed (yr) Width Length

D4045 SI12273 MB 2 -- --
-- C3260 MB 8 -- --
-- C2003 MB 12 -2.8 1.5
D4059 T2288 MB 3 0.2 0.6
-- T2088 MB 4 0.4 0.7
-- T2201 MB 3 0.4 0.3
D4077 T2297 MB 3 -0.5 -0.7
D4091 T2824 MB 3 0.6 0.9
-- T2372 MB 3 -- --
-- H1955 KSC 7 0.9 0.9
D4116 H1906 KSC 7 0.5 0.4
-- E9270 MB 10 -- --
D4118 FL1901 CNS -
D3889 GA1317 GA 2 -- --
D4019 T2273 MB 3 1.2 -0.2
D4020 16483 MB 4 1.6 1.0

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