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




                                                                      FY 1992 FINAL PRODUCT Task 14
                                                                               Land Planning for Eagle Mgt.





                
                    Production and Implementation of a Habitat Suitability Model
                   for Breeding Bald Eagles in the Lower Chesapeake Bay
                                  (Model Construction through Habitat Mapping)



                                                  Bryan D. Watts
                                          Center for Conservation Biology
                                            College of Willian & Mary


                                                  Mitchell A. Byrd
                                          Center for Conservation Biology
                                            College of William & Mary,


                                               Georgia E. Kratimenos
                                          Center for Conservation Biology
                                            College of William &.Mary


                     Final Report to:   Virginia Department of Game and  Inland Fisheries
                                              (Nongame and Endangered Species Program)



                                                             
                                               Project sponsored by:
                                        Virginia Environmental Endowment

                                  Virginia Department of Environmental Quality
                                 Virginia Coastal Resources Management Program

                                 Virginia Department of Game and Inland Fisheries
                                    Nongame and Endangered Species Program


                                                    January  1994

                                 This paper is funded in part by a grant from the National Oceanic and
                               Atmospheric Administration. The views expressed herein are
                                 those of the authors and do not necessarily reflect the views of NOAA
                                 or any of its sub-agencies.















                      Rec'd by Dept. Of
                    Environmental Quality

                         FEB 11 1994


                         Public & Inter-
                     governmental Affairs













                 Production and Implementation of a Habitat Suitability Model
                     for Breeding Bald Eagles in the Lower Chesapeake Bay
                               (Model Construction through Habitat Mapping)



                                               conducted by




                                             Bryan D. Watts
                                      Center for Conservation Biology
                                        College of William & Mary


                                             Mitchell A. Byrd
                                      Center for Conservation Biology
                                        College of William & Mary


                                          Georgia E. Kratimenos
                                      Center for Conservation Biology
                                        College of William & Mary










                                                  SUNEW,RY


                 Since its elevation to endangered status in 1978, protection of the Bald Eagle and its

          habitat is governed by the Endangered Species Act. Under this designation, critical habitat is

          defined as any area essential to the survival and recovery of the species. Current habitat

          management strategies for nesting Bald Eagles are centered around the protection of active

          nest trees. Although this practice is essential, it does not address potential nesting habitat.

          Much habitat remains unoccupied that is both critical to the continued recovery and

          maintenance of the population and is under imminent risk of development.

                 We quantified 61 topographic, landuse, and disturbance variables within 127 active

          eagle territories and around 127 randomly chosen points to evaluate their potential as

          predictors of habitat quality for breeding Bald Eagles. Fifty-four of 61 variables were

          significantly different between the two samples. Compared to random sites, eagles prefer to

          nest in areas situated close to large water bodies, away from extensive human disturbance,

          and having considerable forest cover.

                 A discriminant function analysis was used to determine the linear combination of

          variables that best differentiate between active and random sites. Sixteen variables


          conforined to parametric assumptions and were entered into a step-wise discriminant function

          procedure. The final 4-variable model constructed produced a classification accuracy of

          81.5 %. In addition to the model variables, 4 distribution constraints were identified within

          the data set. A combination of these constraints and the 4-variable model were used in the


          final land classification model.


                 The final model was used to classify lands along a 100 mi. reach of the James River

          and a 75 mi. reach of the Rappahannock River. All lands along these drainages or their










          tributaries that fell within 3 kin of a channel at least 250 in wide were classified. This land


          mass included over 2,300 km. Classification of the area was accomplished by establishing a

          network of over 15,000 registration points, parameterizing the model variables for each point

          independently, and employing the classification model.

                 A substantial portion of the James and Rappahannock River drainages (458 and 274

          kni@ respectively) was classified as unsuitable due to high housing density and/or the lack of

          adequate nesting substrate. However, a comparable portion of both drainages was also found

          to contain either good or very good habitat for breeding (344 and 349 Ian' for the James and

          Rappahannock Rivers respectively). Relationships between habitat quality and the model

          variables were consistent with those expected based on the univariate results.












                                           ACKNOWLEDGEMENTS


                 Financial support for this project was provided by the Virginia Environmental

          Endowment, the Virginia Department of Environmental Quality's Coastal Resources

          Management Program and the Virginia Department of Game and Inland Fisheries' Nongame

          and Endangered Species Program. We acknowledge these agencies for supporting new

          initiatives in Bald Eagle management.

                 This study would not have been possible without the hard work of many students and

          associates of the Center for Conservation Biology including: Lanny Bear, Susan Summers,

          Amanda Allen, Michelle Mabry, Jennifer D'Amico, Brian Dougherty, Megan Davis, Jeff

          Norgard, and Ellen McLean. Ellen McLean in particular supervised and coordinated the

          collection of the initial data. Dana Bradshaw collaborated on the initial planning of the

          project and provided much needed logistical support from the Department of Game and

          Inland Fisheries.


                 Production and printing of the final GIS-based classification maps was done by Steve

          Phillips of the Virginia Department of Game and Inland Fisheries BOVA program under the

          direction of Becky WaJda. We appreciate their efforts toward the completion of the final

          maps. This document is publication number 5 of the Virginia Center for Conservation

          Biology.











                                                 WRODUCTION


                 One of the primary threats to wildlife, and concomitantly, one of the leading causes

          of species extinction, is the loss of habitat due to urbanization. As the human population

          expands and natural areas are developed for residential, commercial and industrial use,

          critical wildlife habitat is rapidly disappearing. Changes in landuse patterns are widespread

          and conversion rates are high for many physiographic regions. However, due to their natural

          appeal, coastal lands are experiencing some of the highest development pressures. Greater

          than 52 percent of the U.S. human population now lives within 80 Ian of U.S. coastlines.

          Between 1950 and 1986, the number of people living along the shores of the Chesapeake Bay

          increased by 50 percent. This population is projected to increase by at least 2.6 million, or

          an additional 20 percent, over the next 30 years. Wiffiin the greater bay area, pressures on

          habitats associated with highly desirable waterfront property are immense. In Maryland, a

          survey in the early 1980's showed that nearly 20 percent of all development activity in the

          state was occurring within one thousand feet of the edge of the bay and its tidal tributaries.

          Construction of 53,000 family dwellings within this thin ribbon is expected to occur within

          the near future.


                 Historically, the Bald Eagle was a common breeder along major river systems, lakes

          and coastal areas throughout the Southeast. The widespread use of persistent pesticides for

          crop management in the region resulted in dramatic declines over a 30-40 year period. By

          the late 1960's most breeding populations had been decimated by eggshell thinning and

          associated low productivity. Concern for these populations prompted the elevation of the

          Bald Eagle to endangered status and led to a national effort to restore historic populations.









         Since the nationwide ban on most persistent pesticides in 1972, many populations have

         experienced gradual recoveries in both productivity and total numbers. In Virginia, the

         breeding population has steadily increased from an estimated low of approximately 32 pairs

         in the 1960's to 151 pairs in 1993. Shoreline development poses the most significant threat

         to the recovery and long-term persistence of Bald Eagles within the Chesapeake Bay.

         Breeding pairs require open water for foraging and rarely build nests beyond 1-2 Ian of the

         shoreline. T'his suggests that all current and potential breeding habitat lies within the same

         thin ribbon of land currently experiencing the most rapid development.

                 Since its elevation to endangered status in 1978, protection of the Bald Eagle and its

         habitat is governed by the Endangered Species Act of 1973. Under this designation, critical

         habitat is defined as any area essential to the survival and recovery of the species. Current

         habitat management practices for nesting Bald Eagles have focused on protecting active nest

         trees and restricting landuse activities within "recommended" buffer zones. This passive

         strategy does not address potential nesting habitat. During the course of this recovery phase,

         much habitat remains unoccupied that is both critical to the continued recovery and

         maintenance of the population and is under imminent risk of development. Little attention

         has been given to the delineation of these lands that are critical to the Chesapeake Bay eagle

         population.

                The principal objectives of this study are: 1) to parameterize and screen a series of

         relevant landuse variables for their ability to predict habitat quality for breeding Bald Eagles,

         2) to construct a quantitative tool capable of delineating lands in Virginia's coastal plain

         according to their value as habitat for breeding Bald Eagles, and 3) to delineate lands in



                                                        2








         selected "demonstration" areas for the purpose of providing local jurisdictions with the

         information needed to make informed decisions regarding land use and habitat needs of Bald

         Eagles.

                Project objectives were to be accomplished in two distinct phases. Phase I to include

         data collection and model construction and Phase II to include model implementation and

         land classification. This report is intended to give a brief overview of the methods, results,

         and products of these two project phases (project phases presented sequentially).


































                                                       3







                       as


           Data Collection/Model Construction
              Ph                    I










                                                  APPROACH


                 During the process of territory selection, Bald Eagles are likely influenced by a

         complex collage of factors that vary from the structure of a landscape to the size and form of

         an individual tree. How this suite of factors interact to influence the distribution of breeding

         pairs is beyond the scope of any single investigation. However, predicting the impacts of

         alternate landuse decisions on the potential of habitat for breeding does not require an

         understanding of all possible habitat variables. We have chosen to narrow our focus here

         from all possible factors to those that are directly relevant to landuse patterns. By doing so

         we do not dismiss the importance of other factors, but instead highlight those that are most

         useful for the construction of local landuse policies.

                 We have chosen to evaluate factors in three broad classes including: 1) topographic

         variables (parameters that describe long-lived landscape features), 2) landuse variables

         (parameters that describe landuse features as they exist in 1992), and 3)

         disturbance/development variables (parameters that describe the extent of human

         impacts/development as it exists in 1992).    Topographic variables (e.g. availability of open

         water or marsh, distance to nearest waterways) are relatively stable features of the landscape

         and are used to effectively reduce the land area under consideration. In other words, if

         eagles are found to nest only within particular topographic constraints then decisions

         concerning lands that fall outside these constraints will have relatively little impact on

         potential breeding habitat. Landuse variables (e.g. amount of land in forest or agriculture)

         are also relatively stable and are used to further refine habitat potential within those areas

         that meet topographic constraints. Disturbance/development variables (e.g. housing density,



                                                        4









          miles of roadways) are currently the least stable and are changing at a rapid rate as

          development continues to expand across the coastal plain. These variables will be used to

          further refine the distribution of potential habitat that meets both topographic and landuse

          constraints.


                 This hierarchical approach to land delineation allows for the systematic exclusion of

          unusable lands by "filtering" them out based on a series of appropriate constraints (see

          Figure 1). Using the limited number of factors mentioned above, this approach gives a

          conservative representation of potential habitat based solely on current landuse patterns. The

          addition of other classes of factors (e.g. distribution of prey populations, distribution of

          occupied habitat) would serve to refine usable habitat still further.

                                                 STUDY AREA


                 We confined our investigation to the coastal plain of Virginia from the Atlantic Ocean

          (including the Delmarva peninsula) west to the fall line and from the Virginia bank of the

          Potomac south to the southern bank and associated tributaries of the James River. This area


          includes over 20,000 sqlan of land drained by four major rivers and numerous large

          tributaries.


                 Much of the land included in the study area is currently used for agriculture and

          timber production. Large urban centers are situated around the mouths of larger rivers and

          their tributaries. Significant metropolitan areas also exist along the fall line near the end of

          navigable waters. Although much of the landscape remains rural, lands between urban

          centers are increasingly being converted for residential use, particularly along prominent

          shorelines.




                                                        5






























         Figure 1. Conceptual Model illustrating the filter approach to land classification. Shown is
                       the reduction in potential land with the application of successive constraints.



























           FILTER APPROACH
          TO LAND DELINEATION



                      Total Land Area



                 Topographic Constraints


                     Land Within Topographic Constraints


                 Landuse Constraints


                     Land Within Landuse Constraints


              >  Disturbance Constraints

                     Potential Breeding Habitat
               @
                   graphi(


                     I
                 op :
                  0






                  duse  Cc



























   Figure 1

                     6










                                                 METHODS


         Active Breeding Areas

                We define a "breeding area" as the landscape included within and surrounding the

         complex of nests that a pair of breeding eagles use over the course of several years. We

         confined this study to those breeding areas containing a nest known to be active during the

         1992 breeding season. The status and location of nests was determined during aerial surveys

         conducted throughout the early spring of 1992. A nest was considered to be active if an

         adult eagle was observed on the nest in an incubating posture. Aerial surveys resulted in the

         location of 127 active nests within the study area during 1992.

         Random Points


                In order to focus the investigation on relevant variables, all known active and historic

         nesting sites were examined collectively to uncover any topographic constraints. One

         distribution constraint emerged. Nearly all known nest sites (N = 367) appear to be within

         3 Ian of a channel that has a minimum width of 250 m. This single constraint was used to

         redefine the working area for the selection of all random locations.

                Random locations were used to represent the general availability of habitat variables

         for comparison to active sites. Random sites were initially chosen on a 1:250,000 scale

         topographic map of the study area by overlaying a transparent, 10,000 cell grid and choosing

         random coordinates without replacement. Only coordinates falling within the defted

         working area were retained for analysis. Random coordinates were chosen until 127 points

         were accumulated. Plotted points were then transferred, as accurately as possible, onto 7.5

         min topographic maps.



                                                       7









                 Upon closer examination of random point locations, 22 were found to be situated

         within active, old or new (1993) territories. In order to achieve a clearer separation between

         active and random sites, these points were reclassified as active before analysis.

         Habitat Variables and Data Collection


                  Active nest sites were the focal points for data collection and were used to establish a

         nesting area (NA), (see Figure 2) and a foraging area (FA) for each territory. These study

         plots were used to investigate habitat variables that might directly influence nest placement

         and primary foraging areas respectively and ultimately the location of breeding territories.

         The NA included all of the area within a 1600 m radius of the nest site. Because many of

         the nests were located well beyond 1 - 2 Ian from major drainages, the same approach could

         not be used in delineating the FA (i.e. if a fixed radius from the nest was used, the FA

         variables would be highly influenced by the distance to water). This problem was avoided

         by drawing a line from the nest to the nearest shoreline point on a channel > 100 m wide.

         This point was considered the "nearest shoreline point" (see Figure 3). The FA included all

         of the area associated with the shoreline within a 1600 m radius of this designated point. We

         assumed that this area included the shoreline most used by the resident pair. The same

         procedure outlined above was used to determine both the NA and FA for each randomly

         chosen location.


                 Habitat variables measured within each NA and FA were divided into three general

         categories. Categories included: 1) topographic variables, 2) disturbance variables, and 3)

         landuse variables. Tables 1 and 2 give a brief description of all variables measured.





                                                         8






























         Figure 2. Illustration of nest area plot where all NA variables were quantified. Note that
                       many of the variables were stratified to the various concentric rings shown.













                           NEST AREA (NA)








                                                800 m
                                     00 m                   1600 m
                              0 m


                                     NE































                                                                          0



       Figure 2

                                         9






























         Figure 3. Illustration of the foraging area plot where all FA variables were quantified. Plot
                      was located by extending a perpendicular to the "nearest shoreline point"
                      associated with a channel greater than 100 m wide. All shoreline enclosed
                      within a 1600 m radius of the nearest point was considered the focal shoreline.












                          FORAGING AREA (FA)




                            FOCAL SHORELINE




                                 NEAREST
                              SHORELINE POINT




                         1600 M            Ic








                             NEST
                                         ND ULAR


























      Figure 3

                                      10














          TABLE 1. Variables measured within 1600 m of active nest sites and random
          sites.

          Code      (units)                   Variable Description

          TOPOGRAPHIC
          DISCH1     (m)     Distance to nearest open channel <100 m wide.
          DISCH2     W       Distance to nearest open channel >100 m wide.
          DISCH3     W       Distance to nearest open channel >250 m wide.
          DISCH4     W       Distance to nearest open channel >500 m wide.
          DISCH5     W       Distance to nearest open channel >1 km wide.
          MSHAR1     (ha)    Area   of  marsh  within a 200 m radius.
          MSHAR2     (ha)    Area   of  marsh  within a 400 m radius.
          MSHAR3     (ha)    Area   of  marsh  within an 800 m radius.
          MSHAR4     (ha)    Area   of  marsh  within a 1600 m radius.
          MSHAR5     (ha)    Area   of  marsh  between 200 and 400 m from point.
          MSHAR6     (ha)    Area   of  marsh  between 400 and 800 m from point.
          MSHAR7     (ha)    Area   of  marsh  between 800 and 1600 m from point.
          WATAR1     (ha)    Area   of  water  within a 200 m radius.
          WATAR2     (ha)    Area   of  water  within a 400 m radius.
          WATAR3     (ha)    Area   of  water  within a 800 m radius.
          WATAR4     (ha)    Area   of  water  within a 1600 m radius.
          WATAR5     (ha)    Area   of  water  between 200 and 400 m from point.
          WATAR6     (ha)    Area   of  water  between 400 and 800 m from point.
          WATAR7     (ha)    Area   of  water  between 800 and 1600 m from point.

          DISTURBANCE
          DISUNR W           Distance to nearest unimproved road.
          DISSCR W           Distance to nearest secondary road.
          DISBLD W           Distance to nearest building.
          LWRDN1    (m/km)   Length   of  unimproved    roads   within 200 m radius.
          UNRDN2    (m/km)   Length   of  unimproved    roads   within 400 m radius.
          UNRDN3    (m/km)   Length   of  unimproved    roads   within 800 m radius.
          UNRDN4    (m/km)   Length   of  unimproved    roads   within 1600    m radius.
          UNRDN5    (m/km)   Length   of  unimproved    roads   between 200    and 400 m.
          UNRDN6    (m/km)   Length   of  unimproved    roads   between 400    and 800 m.
          UNRDN7    (m/km)   Length   of  unimproved    roads   between 800    and 1600 m.
          SCRDN1    (m/km)   Length   of  secondary    roads   within 200 m    radius.
          SCRDN2    (m/km)   Length   of  secondary    roads   within 400 m    radius.
          SCRDN3    (m/km)   Length   of  secondary    roads   within Boo m    radius.
          SCRDN4    (m/km)   Length   of  secondary    roads   within 1600 m radius.
          SCRDN5    (m/km)   Length   of  secondary    roads   between 200 and 400 m.
          SCRDN6    (m/km)   Length   of  secondary    roads   between 400 and 800 m.
          SCRDN7    (m/km)   Length   of  secondary    roads   between 800 and 1600 m.
          BLDDN1    (N/km)   Number   of  buildings    within 200 m radius.
          BLDDN2    (N/km)   Number   of  buildings    within 400 m radius.
          BLDDN3    (N/km)   Number   of  buildings    within 800 m radius.
          BLDDN4    (N/km)   Number   of  buildings    within 1600 m radius.
          BLDDN5    (N/km)   Number   of  buildings    between 200 and 400 m.
          BLDDN6    (N/km)   Number   of  buildings    between 400 and 800 m.
          BLDDN7    (N/km)   Number   of  buildings    between 800 and 1600 m.













          TABLE 1.        -- Continued

          Code      (Units)                Variable Description

          LANDUSE
          CLCTAR     (ha)    Area of clearcut land within 400 m radius.
          YGFRAR     (ha)    Area of young forest coverage within 400 m radius.
          IMFRAR     (ha)    Area of intermediate age forest coverage within
                             400 m radius.
          MATFAR     (ha)    Area of mature forest coverage within 400 m
                             radius.
          FRWTAR     (ha)    Area of forested wetland coverage within 400 m
                             radius.
          FORARI     (ha)    Total area of forest coverage within 400 m radius.
          FORAR2     (ha)    Total area of forest coverage within 1600 m
                             radius.
          AGLAAR     (ha)    Area of agricultural land within 400 m radius.
          URLAAR     (ha)    Area of urban land within 400 m radius.



          TABLE 2. Habitat variables measured within foraging area (1600 m radius
          around shoreline point nearest to nest or random point).

          Code      (Units)                 Variable Description

          TOPOGRAPHIC
          MASHLE W           Length of shoreline composed of marsh within
                                 foraging area.
          UPSHLE W           Length of shoreline composed of upland within
                                 foraging area.
          TOSHLE W            Total shoreline length within foraging area.

          DISTURBANCE
          BLDDEN (N)         Number of buildings within 200 m of foraging area.
          PIRDEN (N)         Number of piers or docks within foraging area.

          LANDUSE
          FORSH1 (m)         Length of shoreline, within foraging area, with
          forest   buffer   <50 m wide.
          FORSH2 W           Length of shoreline, within foraging area, with
          forest   buffer   >50 m wide but <150 m wide.
          FORSH3 W           Length of shoreline, within foraging area, with
          forest   buffer   >150 m wide.
          TFORSH W           Total length of forested shoreline within foraging
                                 area.


























                                                          12









          Variable Measurement and Analysis

                 Measurements of habitat variables were taken from 7.5 minute USGS topographic

          maps or on recent aerial photographs. The vast majority of photographs used were obtained

          from the U.S. Department of Agriculture's (USDA) office of Agricultural Soils Conservation

          Service and were 1: 16000 scale, black and white. A few photographs were obtained from

          the Virginia Department of Transportation (VDOT) to fill gaps in coverage and were

          1: 12000 scale, black and white. Date of aerial photography was 1988-89 for USDA and

          1986-89 for VDOT. The season of photographs ranged from October - April. Distance

          measurements were made using a millimeter ruler, lengths and areas were measured using an

          electromagnetic digitizing tablet (see Appendix I for details on individual measurements).

                 Lilliefor's test was used to assess distribution patterns for each variable. All non-

          normal variables were transformed using three standard functions (including: 1) log(X + 1),

          2) (X)II, and 3) arcsine(X)) and retested. Significance between active and random points

          was evaluated using an F-test for all parametric variables and Mann-Whitney U test for all

          nonparametric variables. Significance levels of 0. 15 were used to control the Type H error.

          When the null hypothesis was accepted (i.e., the means were equal) it was assumed that the

          eagles were using the variable according to its availability and it, therefore, was excluded

          from further analysis. A correlation matrix was generated for all significant, parametric

          variables to investigate variable independence. When two or more variables were highly

          correlated, the variable that was most easily interpreted or measured was retained.







                                                         13









                All variables surviving the above criteria were processed in a discriminant function

         procedure using active vs random as the grouping parameter. A procedure to maximize

         Wilk's Lambda was employed using equal prior probabilities.

                                 OVERVIEW OF UNIVARIATE RESULTS


                Nest site selection for Bald Eagles within the study area appears to be influenced by

         several habitat dimensions. Univariate test results (see Appendix II for a full accounting of

         the results) revealed that active nest sites were significantly different from random sites with

         respect to 54 of 61 habitat variables measured. In general, eagles prefer to nest in areas that

         are situated close to large water bodies, away from extensive human disturbance, and having

         considerable forest cover.





         Nest Area


                                                  Tgpograhy

                Despite the fact that the selection of random points was constrained to within 3 kni of

         a large water body, active sites were still significantly closer to the entire range of channel

         widths measured (see Figure 4). However, the average distance to water was positively

         related to channel width for both active and random sites. This seems to suggest that

         although nests tend to be closer to all channels thati expected eagles are not selecting any

         particular channel width. In essence nest sites tend to be close to narrow channels because

         narrow channels are comparatively more abundant and widespread than wider channels.

                In addition to being near water, "nest areas" associated with active sites contained

         significantly more marsh and open water when compared to random sites (see Figure 5).



                                                       14































         Figure 4. Comparison between active and random sites in distance to channels of various
                     widths. Histograms indicate + or - one standard error.











                    DISTANCE TO NEAREST CHANNEL OF
                                   OPEN WATER

               4000




                                                             ...........
               3000
           E

                                                                     Active
           C=  2000                                                  Random
           .9-


                1000



                   0
                       <loom >I@Orn >250m >500m >1000m

                                    Channel Width




















      Figure 4

                                     15






























         Figure 5. Comparison between active and random sites in area of open water and marsh.
                     Categories A, B, C, and D indicate concentric rings moving outward from the
                     nest (0 - 200 m, 200 - 400 m, 400 - 800 m, and 800- 1600 m respectively).
                     Histograms indicate means + or - one standard error.













                                                                         Open Water

                                    20            m AOTIVE
                                                  0 RANDOM

                                    15


                            E-=                                                                                    ............ ..
                        co                                                                                       ........... . . . . . .......
                        Wo CNr-     10

                            cc


                                      5



                                                       . . . . . . . . . . . . . . . .
                                      0
                                                     A                  B                   c                  D

                                                                          CATEGORY







                                                                                Marsh

                                   30                                                                   M ACTIVE
                                                                                                        m RANDOM



                                   20
                           E-=
                       cc



                                   10




                                                      NN
                                     0
                                                    A                   B                  C                   D
                                                                        CATEGORY





            Figure 5

                                                                     16









         This result does not appear to be an artifact of proximity to water (as might be expected with

         the fixed radius measurements employed). Area of water or marsh was not negatively

         correlated with distance to water (P > 0.05). This seems to suggest that eagle pairs are

         selecting areas along the shoreline that have concentrations of marsh and open water.

                                                   Disturbance


                Active nest sites and random points were significantly different with respect to their

         location relative to all human-related structures examined (see Appendix I for summary of

         test results). Nest sites were generally distributed further from all disturbance types. The

         occurrence of disturbance structures within NA sample plots was also different between

         random and active sites with active sites having significantly lower densities. This suggests

         that eagles are selectively breeding in locations away from human-related structures.

                 In addition to the lower overall density of structures, active and random sites differed

         in the spatial arrangement of disturbance structures within NA plots (see Figure 6). For

         active sites, density increased significantly with distance for all three structure types

         (Kruskal-Wallace statistic > 100.0 and P < 0.001 for all types). The same pattern was not

         detected within random plots (Kruskal-Wallace statistic < 7000 and P > 0.05 for all types).

         The disparity in these spatial patterns (between active and random plots) is illustrated by the

         significance patterns for distance/disturbance categories and suggests that eagle sensitivity to

         all of these structures declines with distance.


                                                    Land-use


                 Land-use patterns differed significantly between active and random locations. Active

         nest sites were surrounded by comparatively more forest cover (within both 400 and 1600



                                                       17



























         Figure 6. Comparison between active and random sites in disturbance variables. Categories
                     A, B, C, and D indicate concentric rings moving outward from the nest (0 - 200
                     m, 200 - 400 m, 400 - 800 m, and 800 - 1600 m respectively). Histograms
                     indicate means + or - one standard error.













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                  100
                     0
                            UnImp          Enow=         BICIg
                                   I'lo-Amcl/SullcSing


       Figure 6

                                       18









         in), less agricultural land, and less urban development (see Figure 7). Forest coverage for

         active sites was not only more extensive but also exhibited a different age distribution.

         While random sites had comparatively more area in intermediate age forest, active sites

         contained significantly more mature forest. Active and random sites were not significantly

         different with respect to land area in clearcut and young forests.

         Foraging Area

                Results were mixed in terms of comparisons between random and active sites for

         shoreline characteristics (see Figure 8). Total shoreline length within the defined foraging

         area was significantly higher for shorelines associated with random sites, suggesting that

         active shorelines were less convoluted. The length of shorelines designated as marsh or

         unclassified uplands did not differ between the two samples. Shorelines associated with

         random points had greater numbers of houses and associated piers along their lengths when

         compared to active shorelines. No difference was detected between the two samples

         regarding any of the measurements for length or width of forested shorelines.



















                                                       19





























         Figure 7. Comparison between active and random sites in the area of surrounding lands in
                      various landuse categories. Histograms indicate means + or - one standard
                     error.


















                                               Land Use within 400 M

                             120
                             110
                             100
                              90
                              80
                        ES
                          C   70                                                                        = Active
                        c:;-  60                                                                        M Random
                              so                                      . . . . . . . . . .
                              40
                              30
                              20
                              10
                                0
                                      Total Forest           Agriculture             Urban

                                                              Land Use





                                              Forest 'Types within 400 M

                              70

                              60

                              so
                                                                                                         = Active
                      C" bc   40
                         =;,                                                                             M Random
                              30

                              20

                              10

                                0
                                       Clear.out         Young        Intermed          Mature
                                                              Forest Type





                                                Forest Coverage within 1800 M

                             100
                                                                                                            Activ
                              90                    .. ..
                                                       ... . ... .. . ... ......
                                                                                                                   :m
                              80                                                                            Rand
                              70
                              60
                         C@-  so                 ..... ......
                     -ZE 41@
                              40
                              30
                              20
                              10
                                0
                                                        Forest     4@ovarage


          Figure 7

                                                          20































         Figure 8. Comparison between active and random sites in the density of buildings within
                      200 m and 400 m. Histograms indicate the relative frequency of sites with
                     respective building densities.














                            Shoreline within Foraging Area


                9000

                7500
            IEff'                                                     Active
            -=  8000                                               so Random
                4500

                3000

                1500

                    0
                           Marsh         Upland        Total
                                      Shoreline Type







                              Houses/Piers within Foraging Area

                   36

                   30
                   25                                     . . . . . .
                   20                                              = Active
                                                                   M Random


                   10



                    0                                 . .. ....
                               Houses               Piers
                                    Shoreline Category






                          Forested Shoreline within Foraging Area

                5000


                4000


                3000                                               W Active
                                                                      Random
                2000


                1000                    . . . . . . . . . . .1.


                    0
                          -50m      50-150m   -150M      Total
                              Forested Shoreline Category


      Figure 8

                                      21










                                            THE MODEL


              Sixteen variables survived the selection criteria and were evaluated using a direct

        discriminant function procedure. This procedure resulted in the following linear combination

        of variables:





                        02971984 X DISCH1
                     -.02264714 X DISCH2
                     -.01185676 X DISCH3
                        00060520 X DISCH4
                        00521514 X DISCH5
                     -.00042232 X MSHAR4
                     +.03209294   X DISUNR
                     *  .02622746 X DISSCR
                     *  .04761829 X DISBLD
                     *  .00321745 X UNRDN4
                     *  .00093799 X FORAR2
                     *  .00399596 X FORAR1
                        16315130 X SCRDN2
                     +  .00135922 X SCRDN4
                        04559869 X BLDDN4
                     +.03957766 X BLDDEN
                 -1.126655   (constant)


               To further evaluate these variables and help assess their relative predictive value

        across the full range of conditions, 50 randomly selected subsets, each comprising 75% of

        the observations, were chosen and run through a 15-step DFA. On average, eight variables

        entered into the functions before variable selection stopped due to the low F-values for

        remaining variables. Two variables (DISBLD and DISUNR) entered into the functions on

        every run, one variable (DISUNR) entered 49 times, and three variables (DISSCR, DISCH2,

        and FORAR2) entered 43 times. The high loading frequency and high mean rank of these

        six variables suggest that they have superior discriminating power (Table 3).


                                                 22
















       Table 3. Loading frequency and mean rank of variables entered
       into discriminant analysis of 50 randomly selected subsets.

       Variable      Transformation         N          Mean Rank        S.E.
                                         (freq)

       DISBLD             X112             50            1.000        0.000
       DISCH1             x1/2             50            4.140        0.200
       DISUNR             XI/2             49            5.735        0.130
       DISSCR             x1/2             43            2.674        0.239
       DISCH2             x1/2             43            3.349        0.199
       FORAR2             ----             43            5.000        0.160
       SCRDN2           Log(l+X)           39            6.282        0.348
       DISCH5             x1/2             22            7.000        0.147
       DISCH3             x1/2             19            6.316        0.459
       FORAR1            ----              16            5.688        0.561
       UNRDN4             x1/2             11            8.364        0.279
       DISCH4             x1/2              9            6.778        0.641
       MSHAR4            ----               4            8.500        0.289
       SCRDN4           Log(l+X)            3            7.667        0.882
       BLDDEN           Log(I+X)            3          8.333          0.882
       BLDDN4           Log(l+X)            1           10.000        -----























                                            23









                 To evaluate the sensitivity of the discriminant model to the six-variable set,

          classification rates were examined from runs with each variable excluded in sequence (Table

          4). Results from this sensitivity analysis suggest that DISUNR and FORAR2 do not

          contribute a great deal to the classification accuracy of the model. This result is consistent

          with their average loading positions (see Table 3 ). For ease of implementation, these

          variables were omitted from the final model.


                 The final 4-variable model is presented in Table 5 and produced a classification

          accuracy of 81.5 %. Figure 9 shows the distribution of discriminant scores for both active

          and random points. Scores ranged from a low of -2.8396 for random sites to a high of

          4.7340 for active nest sites. The range of highest overlap between the two groups was

          between -1.25 and 0.25. Discriminant scores were rescaled from 0 to 100 for ease of


          interpretation using the following equation:

                                Habitat Quality (HQ) = (DS + 2.8396)/0.075736

                 Four categories of habitat quality were derived from the distribution of habitat values.

          These categories included: 1) 0 - 21 corresponding to exclusively random sites (except for

          one nest outlier), and 2) 22 - 34 corresponding to the range of greatest overlap. These two

          categories were labelled questionable and acceptable. Beyond the range of greatest overlap,

          the remaining range was split fairly evenly to form two additional categories including: 3) 35

          - 67 and 4) 68 - 100 labelled good and very good respectively.

                 To assess the classification accuracy of the final model across the full range of

          conditions, 20 hold-out runs were conducted. A model was first generated using a random

          portion (75 %) of the total cases. The model equation was then used to compute scores and



                                                         24















       Table 4. Classification rates of truncated six-step model with
                  one variable withheld.


       Variable                Misclassified             Classification
       withheld      Random    Active      Total           Rate   (01)


       -------       is           32        47                    81.50
       DISSCR        17           33        50                    80.31
       DISCH2        16           32        48                    81.10
       DISBLD        17           30        47                    81.50
       DISCH1        18           28        46                    81.89
       DISUNR        13           32        45                    82.28
       FORAR2        13           32        45                    82.28













































                                         25




















       TABLE 5. Coefficients for variables entered into the final four-
                 variable model.


       Variable'               Transformation           Model Coefficient


       Constant                      ------            -1.456741
       DISSCR                        W   1/2            .4155321 X 10-'
       DISBLD                        W   1/2            .7842094 X 10-'
       DISCH1                        (x) 1/2          -.2893781 X 10-1
       DISCH2                        W   1/2          -.2205771 X 10-1

           See Tables 1 and 2 for    variable descriptions.

































                                          26



























  I
















         Figure 9. Frequency distribution of discriminant scores for active and random sites.









                             DISTRIBUTION OF SCORES
             20            RANDOM                                         ACTIVE







         UU
              10
         C3
         UU
         cc
         U-








               0


                        w CD m CD w C> w Co w c@ w w C) w CD w CD w CD w CD Ln 01 C>
                                                . . . . .                         cn
                                                                             CM Cn A


                                    DISCRIMINANT SCORES




        Figure 9

                                             27








         classify the remaining hold-out cases (25 %). Classification rates ranged from 65.6 % to

         85.9 % (see Table 6). Of the 1280 cases withheld during the 20 runs, 79.5 % were classified

         correctly. This result suggests that the 4-variable model is reasonably robust over the range

         of conditions within the data set.


                                       ADDITIONAL CONSTRAINTS


                Because of the parametric constraints imposed on variables used in this sort of

         multivariate analysis, several variables that clearly bear on the distribution of eagles were

         excluded from the model. These variables were examined for their value in reducing the

         time and energy needed for model implementation. For this purpose some of these variables

         were incorporated into the final model in the form of constraints. These constraints were

         used as a "quick and dirty" method of determining whether or not the full array of

         parameters were needed to classify a given location as unsuitable. Four such constraints

         were identified including: 1) distance to water, 2) building density within 200 in, 3) building

         density within 400 m, and 4) presence or absence of forest cover within 200 m.

                  The first constraint used was distance to water. As mentioned in the methods, the

         distribution of 367 historic nest sites were examined relative to channels of varying widths.

         Five channel widths were addressed including: 1) < 100 m in width, 2) > 100 rn in width,

         3) > 250 in in width, 4) > 500 in in width, and 5) > 1 kin in width. By examining

         accumulation curves arranged by distance (see Figure 10) it was possible to determine what

         proportion of the nest sites would be enclosed by a given distance from a particular channel.

         The distance needed to enclose all nest sites increased with channel width. All of the nests


         were within 2 Ian of small streams. However, the utility of this information in predicting the



                                                      28










          Table 6. Accuracy of the model: classification results for the 20 hold out runs of
          discriminant analysis with maximum four variables.

          RUN         WITHHELD            MISCLASSIFIED         TOTAL MISCLASSIFIED      CLASSIFICATION
                 RANDOM    ACTIVE      RANDOM      ACTIVE                                  RATE (*i)

          1         26       38          5           12                  17                  73.44
          2         27       37          6            7                  13                  79.69
          3         28       36          2           10                  12                  81.25
          4         27       37          1           10                  11                  82.81
          5         25       39          3           11                  14                  78.13
          6         30       34          4            6                  10                  84.38
          7         25       39          5           10                  15                  76.56
          8         30       3A          2           10                  12                  81.25
          9         26       38          3            7                  10                  84.38
          10        28       36          5            8                  13                  79.69
          11        26       38          2            7                    9                 85.94
          12        26       38          4           10                  14                  78.13
          13        26       38          3            9                  12                  81.25
          14        25       39          7           15                  22                  65.63
          15        27       37          6           10                  16                  75.00
          16        27       37          5            5                  10                  84.38
          17        23       41          4            8                  12                  81.25
          18        26       38          6            8                  14                  78.13
          19        26       38          4            9                  13                  79.69
          20        27       37          3           10                  13                  79.69

          TOTAL    531       749         80          182                262








                                                         29
































   I



   I











          Figure 10. Accumulation curves for the proportion of nests within given distances to water
                       bodies with various channel widths.
















                         ACCUMULATION CURVES

             120-

                                                                           <1 oom
             100-                                                    0     >1 oom

                                                                           >250m
             80-
       0                                                                   >500m

       0     60-                                                     0     >1 km

       *AN


             40-



             20-



              0
                0         1000        2000       3000        4000


                                 Distance (m)











  f    Figure 10

                                        30









          distribution of eagles is very low because small streams are distributed widely across the

          entire coastal plain (in essence most points within the coastal plain are within this distance of

          small streams). The channel width that seemed to have the most value in reducing the

          working area was 250 m. This is suggested not only by the accumulation curves but also by

          the fact that when moving up major drainages that contain nesting eagles, pairs tend to

          disappear when the channel narrows to below this width. For a channel width of 250 m,

          virtually all nests are enclosed within a 3 Ian buffer zone. This value was used for the

          distance to water constraint and defines the focal area for model implementation.

                 The second set of constraints used was associated with the density of houses. As

          observed in Figure x, Bald Eagles exhibit a strong aversion to buildings and densities in

          close proximity to nests were low in comparison to background levels. Upon closer

          examination, it was determined that although housing densities were high in many areas,

          eagles did not nest in locations having greater that 5 houses within 200 m or having greater

          than 10 houses within 400 m (see Figure 11). These apparent tolerance limits were used as

          building density constraints.

                 The final constraint used was associated with forest cover. On average, Bald Eagle

          nest sites were associated with more extensive forest cover than was generally available on

          the coastal plain. Because eagles require large, mature trees for nesting it then follows that

          areas devoid of trees would not be potential nesting sites. For this reason, the presence of

          some forest cover was a prerequisite for employing the classification model.







                                                         31






























          Figure 11. Comparison between active and random sites in the density of buildings within
                        200 and 400 m. Histograms indicate the relative frequency of sites with
                        respective building densities.










                      BUILDINGS WITHIN 200 M
                   100
                                              M Act1v:m
                   90                         M Ra nd


                   so


                   70


                   60


                   60


                sr- 40
                CD
                .a-
                7M 30
                ro
                C=
                   20


                   10


                    0                     Fc= P=
                             'r r -ri I   i I

                       1  2 3 4 5 6 7 8 9 10 >10
                                  Buildings (N)





                      BUILDINGS WITHIN 400 M
                 100
                                              0 Aot1ve
                   90                         m Random


                   so


                   70


                   80


                   so


                   40

                LL-
                a, 30


                   20


                   10


                   0                   F=


                       CV    Cl? c? CR         C's CM C@
                       C=p cm 1-w cm C& C:6 .z. 4.6 c,:,
                                  Buildings TN)

       Figure 11

                                      32










                                             THE FINAL MODEL


                 The final land classification model is a combination of the constraints and the final 4-


          variable discriminant function model (see Figure 12). A given site may be classified by first

          employing the sequence of constraints to determine whether or not the site is suitable for

          nesting, and then evaluating the quality of the site by quantitdng the 4 model variables. The

          resulting score may then be rescaled and compared to the ordinal scale to determine relative

          nesting potential.



































                                                       33































          Figure 12. Conceptual illustration of final land classification model. Schematic indicates the
                        process of implementation from the series of constraints to the application of
                        discriminant model. Habitat quality values are rescaled between 0 and 100.
















                                            Land Classification Model




                                   Distribution Constraints


                             s Site Within 3 km of 250 m channel?         No


                                           Yes

                                Is There < 5 Houses Within 200 In?        0

                                           Yes
                                                                                          UNSUITABLE

                              Is'Ibere < 10 Houses Within

                                           Yes



                              Is There Forest Cover Within 200 m?         0



                                         Yes
                                                            HABITNT QUALrIY RA`nNG

                                                                       loo

                                                                          Very Good

                                    Discriminant                       67
                                     Function           Results   h-
                                                                  P@      Good
                                       Model
                                                                       34
                                                                          Acceptable

                                                                       21
                                                                          Questionable

                                                                       0
                              '
                                  be e     @H   ses I
                                    r  < 10  ou
                                                                          N
                                           Yes



                                           t Cc  r
                               s'I  r   @res   @ve
                        =1s The @eFo








           Figure 12

                                                               34









       APPENDIX I: Measurements: USGS topographic maps (1:24,000) and
       aerial photographs dated from 1988-89 (USDA) and 1986-1989 WDOT)
       were used to gather raw data. All active nest locations and
       random points were fixed onto both topographic maps and aerial
       photographs. Concentric circles of 200, 400, 800 and 1600 m
       radii were drawn around all points on the topographic maps.
       Similarly, 400 and 1600 m concentric circles drawn on acetate
       were overlaid on aerial locations to outline different landuse
       areas. An electromagnetic digitizer was used for measuring
       lengths and areas, a millimeter ruler was used for measuring
       straight line distances, and a visual count was employed to
       obtain numbers  of structures.

            Lencfths:  UNRDN1     digitized length of unimproved roads
                                  within 200 m radius directly off topo
                       UNRDN2     added UNRDN1+UNRDN5
                       UNRDN3     added UNRDN1+UNRDN5+LTNRDN6
                       UNRDN4     added UNRDN1+UNRDN5+UNRDN6+UNRDN7
                       U`NRDN5    digitized length of unimproved roads
                                  between 200 and 400 m radius directly
                                  off topo
                       UNRDN6     ""between 400 and 800 mIIII
                       UNRDN7     1111between 800 and 1600 Will


                       SCRDN1     digitized length of secondary roads
                                  within 200 m radius directly off topo
                       SCRDN2     added SCRDN1+SCRDN5
                       SCRDN3     added SCRDN1+SCRDN5+SCRDN6
                       SCRDN4     added SCRDN1+SCRDN5+SCRDN6+SCRDN7
                       SCRDN5     digitized length of secondary roads
                                  between 200 and 400 m radius directly
                                  off topo
                       SCRDN6     ""between 400 and 800 mIIII
                       SCRDN7     ""between 800 and 1600 m


                       MASHLE     digitized along marsh shoreline (200 m
                                  on either side of closest point perp. to
                                  nest)
                       UPSHLE     I'll along upland shoreline""
                       TOSHLE     added MASHLE+UPSHLE


                       FORSH1     digitized length of forested shoreline
                                  (< 50 m wide) within a 1200 m radius
                                  from nest or point off photos only
                       FORSH2     11"(50-150 m wide)IIII
                       FORSH3     1111(>150 m wide)""
                       TFORSH     added FORSH1+FORSH2+FORSH3


            Areas:     MSHAR1     digitized area of marsh within 200 m
                                  radius directly off topo
                       MSHAR2     added MSHAR1+MSHAR5


                                        35










       Appendix I: Measurements    (con't)


                        MSHAR3     added MSHARI+MSHAR5+MSHAR6
                        MSHAR4     added MSHAR1+MSHAR5+MSHAR6+MSHAR7
                        MSHAR5     digitized area of marsh between 200 and
                                   400 m radius directly off topo
                        MSHAR6        between 400 and 800 mIIII
                        MSHAR7        between 800 and 1600 mIIII


                        WATAR1     digitized area of open water within 200
                                   m radius directly off topo
                        WATAR2     added WATAR1+WATAR5
                        WATAR3     added WATAR1+WATAR5+WATAR6
                        WATAR4     added WATAR1+WATAR5+WATAR6+WATAR7
                        WATAR5     digitized area of open water between 200
                                   and 400 m radius directly off topo
                        WATAR6        between 400 and 800 mIIII
                        WATAR7        between 800 and 1600 mIIII


                        CLCTAR     digitized area of clearcut land within a
                                   400 m radius from aerial photographs
                        YGFRAR     ""of young forest coverage""
                        IMFRAR     ""of intermediate age forest coverage"If
                        MATFAR     ""of mature age forest coverage""
                        FRWTAR     1111of forested wetland coverage""
                        FORAR1     added CLCTAR+YGFRAR+IMFRAR+MATFAR+FRWTAR
                        FORAR2     added FORAR1+ digitized area of any type
                                   of forest cover between 400 and 1600 m
                        ALGAAR     digitized area of agricultural use
                                   within a 400 m radius from aerial
                                   photographs
                        URLAAR     I'll area of urban land"If


             Densi.t.y: BLDDN1     visual count of the number of buildings
                                   within 200 m radius off topos or
                                   aerial photographs
                        BLDDN2     added BLDDN1+BLDDN5
                        BLDDN3     added BLDDN1+BLDDN5+BLDDN6
                        BLDDN4     added BLDDN1+BLDDN5+BLDDN6+BLDDN7
                        BLDDN5     visual count of the number of buildings
                                   between 200 and 400 m radius off topos
                                   or aerial photographs
                        BLDDN6        between 400 and 800 mIIII
                        BLDDN7        between 800 and 1600 mIIII


                        BLDDEN     visual count of the number of buildings
                                   along a 200 m wide strip just inside the
                                   1200 m radius off topos
                        PIRDEN     visual count of the number of piers
                                   along shoreline just inside the 1200 m
                                   radius off aerial photos only


                                          36










       Appendix I: Measurements  (con't)



            Distances: DISCH1    measured distance from nest or point to
                                 nearest open channel < 100 m wide using
                                 a millimeter ruler off topo
                        DISCH2      open channel > 100 m wide""
                        DISCH3      open channel > 250 m wide""
                        DISCH4      open channel > 500 m wide""
                        DICSH5      open channel > 1000 m wide""

                        DISUNR   measured distance from nest or point to
                                 nearest unimproved road using a
                                 millimeter ruler off topo
                        DISSCR      to nearest secondary road""
                        DISBLD      to nearest building",




































                                        37









        APPENDIX 11. Descriptive statistics on untransformed variables
        and univariate test results. All statistics presented are F-
        statistics, unless otherwise indicated.

                      Nest (N = 149)       Random (N = 105)
                         x    +    SE          x   +     SE
        Variable           (Range)              (Range)             Stata        P

        DISCH1           309  + 42.7           511 + 40.9           23.9       <0.001
                        (0.0  - 5520)           (24 - 2230)


        DISCH2           686  + 54.1           1090+  80.4          21.1       <0.001
                        (0.0  - 4214)          (72 -  3000)


        DISCH3          1051  + 83.0           1392+  83.3          12.6       <0.001
                        (0.0  - 7501)          (73 -  3000)


        DISCH4          1655  + 147.1          1991+  139.0           6.9      <0.01
                        (0.0  - 10857)         (84 -  7272)


        DISCH5          2471  + 228.9          3026+  235.2           6.2      <0.05
                        (0.0  - 13320)         (84 -  12000)

        MSHAR1           2.7  + 0.31           0.6 +  0.20      10242.0a      <0.001
                        (0.0  - 15.8)          (0.0-  15.0)

        MSHAR2           8.5  + 0.87           2.6 +  0.60      10533 . Oa    <0.001
                        (0.0  - 50.3)          (0.0-  44.1)


        MSHAR3          25.9  + 2.53           11.8+  1.71      10855.5a      <0.001
                       (0.0 - 169.9)        (0.0 - 99.0)


        MSHAR4          88.5 + 7.70            52.5 + 5.50          12.3       <0.01
                       (0.0 - 496.1)         (0.0 - 243.1)

        MSHAR5           5.8 + 0.62            2.0 +  0.44      10722.5a      <0.001
                        (0.0 - 34.6)           (0.0-  29.1)

        MSHAR6          17.4 + 1.83            9.2 +  1.26      11302.5a      <0.001
                       (0.0 - 135.4)           (0.0-  54.9)

        MSHAR7          62.6 + 5.67            40.7+  4.19      11828.5a      <0.01
                       (0.0 - 393.6)         (0.0    171.3)


        WATAR1           0.7 + 0.15            0.1 + 0.05       12263.0a     <0.01
                        (0.0 - 11.0)           (0.0-  2.5)

        WATAR2           4.7 + 0.66            1.9 +  0.65      11776.5a      <0.001
                        (0.0 - 45.3)           (0.0-  58.2)




                                               38









        Appendix 11: --- continued ---
        WATAR3           25.4 + 2.73           11.3 + 2.08        11400. Oa     <0.001
                       (0.0 - 161.6)         (0.0 - 108.1)

        WATAR4         129.5 + 11.08           77.2 +  10.91      11221.0a      <0.001
                       (0.0 - 574.4)           (0.0 -  427.6)

        WATAR5           4.0 + 0.55              1.8+  0.64       11825.5a      <0.01
                         (0.0 - 34.3)          (0.0 -  58.2)

        WATAR6           20.7 + 2.19             9.3+  1.66       11482.0a      <0.001
                       (0.0 - 116.3)           (0.0 -  72.3)

        WATAR7         104.1 + 8.95            66.0 +  9.39       11334.5a      <0.001
                      (0.0 - 463.0)          (0.0 - 416.6)


        DISUNR         475.5 + 30.61         328.7 + 32.14            13.5       <0..001
                      (24.1 - 2361.8)        (24.1 - 1879.8)


        DISSCR         765.0 + 50.97         299.5 + 31.69            82.2       <0.001
                      (48.2 - 4265.7)        (24.1 - 1373.7)


        DISBLD         749.0 + 54.72         252.5 + 24.88            59.8       <0.001
                      (24.1 - 5470.7)        (24.1 - 1373.7)

        UNRDN1           86.4 + 15.17        137.7 + 22.03        14560.5a      <0.05
                       (0.0 - 863.8)         (0.0 - 908.5)

        UNRDN2         391.2  + 44.19        474.0  + 51.73       14451.5a        <0.10
                      (0.0 -  2333.5)        (0.0 - i013.3)

        UNRDN3        1430.3  + 105.08       1624.5 + 137.27      14118. Oa       NS
                      (0.0 -  5157.1)        (0.0 - 9126.9)


        UNRDN4        6091.4  + 292.08       5755.5 + 354.40            1.0        NS
                      (0.0 -  19903.0)       (0.0 - 20235.1)

        UNRDN5         304.8  + 33.30        336.3  + 35.29       14185. Oa       <0.15
                      (0.0 -  1591.0)        (0.0 - 1490.9)

        UNRDN6        1039.1  + 72.19        1150.5 + 112.90      13679.0a        NS
                      (0.0 -  3277.0)        (0.0 - 8303.0)

        UNRDN7        4661.1  + 236.38       4131.0 + 264.09      12502   Oa    <0.15
                      (0.0 -  16688.9)       (0.0 - 14551.7)


        SCRDN1           32.2 + 9.07         334.2  + 46.22       16823   5a    <0.001
                       (0.0 - 610.7)         (0.0 - 2173.2)

        SCRDN2         199.0 + 38.53         1239.4 + 159.58          74.5       <0.001
                       (0.0 - 3817.0)        (0.0 - 8507.7)


                                               39









        Appendix II:      --- continued ---
        SCRDN3        1157.0 + 112.79       4238.8 + 531.23          41.5        <0.001
                       (0.0 - 6317.0)       (0.0 - 30911.7)


        SCRDN4        5747.0  + 364.16     15618.4 + 1846.37         28.4        <0.001
                      (0.0 -  21526.6)     (306.8 - 102914.2)

        SCRDN5         166.8  + 34.09         905.2 + 120.28      17437.5a      <0.001
                      (0.0 -  3817.0)         (0.0 - 6792.7)


        SCRDN6         958.0  + 93.61       2999.4 + 386.50          36.8        <0.001
                      (0.0 -  5820.0)       (0.0 - 22404.0)

        SCRDN7        4589.9  + 291.88     11379.5 + 1341.67      16431 . 5a    <0.001
                      (0.0 -  19344.6) (217.0 - 72002.5)

        BLDDN1            0.2 + 0.06            7.7 + 2.07        16487.5a      <0.001
                             (0 - 8)              (0 - 147)

        BLDDN2            0.9 +  0.17          27.3 + 6.58        18342.5a      <0.001
                            (0-  12)            (0 - 354)

        BLDDN3            8.6 +  1.72         104.8 + 25.92       17971.0a      <0.001
                            (0-  170)           (0 - 1528)


        BLDDN4           59.2 +  11.19        414.2 + 87.82          48.2        <0.001
                          (0    1346)          (0 - 4247)

        BLDDN5            0.7 + 0.15           19.6 + 4.63        18041. Oa     <0.001
                            (0-  12)            (0 - 226)

        BLDDN6            7.7 +  1.65          77.5 + 19.52       17615. 5a     <0.001
                          (0    170)            (0 - 1174)

        BLDDN7           50.7 + 10.15         309.3 + 63.67       16815 . Oa    <0.001
                          (0    1293)          (0 - 3016)

        CLCTAR            3.4 +  0.95       1.5 + 0.58           12873 . Oa     <0.15
                         (0.0 -  73.4)         (0.0 -   35.2)

        YGFRAR            6.8 +  1.28           5.5 + 1.33        13374.0a        NS
                         (0.0 -  80.9)         (0.0 -   80.5)

        IMFRAR           15.1 +  1.77          27.1 +   4.40      15476.5a      <0.001
                       (0.0 - 87.6)           (0.0 - 421.6)

        MATFAR           29.2 + 2.09            7.2 + 1.45           62.9        <0.001
                       (0.0 - 93.9)            (0.0 - 81.6)

        FRWTAR            3.0 + 0.66            0.5 + 0.23        12071. 5a     <0.001
                         (0.0 - 51.1)          (0.0 - 19.5)


                                               40









        Appendix II:      --- continued ---
        FORAR1          57.4 + 1.89           41.7 + 4.70         10195.00      <0.001
                       (0.0 - 109.1)          (0.0 - 440.8)


        FORAR2         738.1 + 24.37          581.0 + 34.58           14.6       <0.001
                      (65.2 - 1497.3)       (0.0 - 1630.6)

        AGLAAR          10.6 + 1.35           24.6 + 2.57         15883.5,1     <0.001
                       (0.0 - 77.8)           (0.0 - 107.7)

        URLAAR            0.4 + 0.14          15.8 + 2.66         15771.0a      <0.001
                       (0.0 - 13.8)           (0.0 - 86.3)

        MASHLE        2331.7  + 188.01      2420.5  + 255.72      13383 . Oa      NS
                      (0.0 -  9544.1)       (0.0 -  12158.9)

        UPSHLE        5397.7  + 307.80      6515.8  + 438.46      14537.52        <0.05
                      (0.0 -  18266.4)      (0.0 -  20742.3)

        TOSHLE        7718.7  + 319.05      9064.8  + 404.16      15049.5a      <0.01
                      (0.0 21963.8)         (3319.3 - 21555.0)


        BLDDEN          10.0 + 1.40           27.1  + 3.60            22.3       <0.001
                          (0 - 120)             (0 - 210)

        PIRDEN            8.4 + 1.27          22.6 + 4.15         16021.5"      <0.001
                            (0 ': 85)           (0 -_353)

        FORSH1        1221.4  + 109.16      1417.6 + 140.39       14028.Oa        NS
                      (0.0 -  5943.5)       (0.0 - 5913.5)


        FORSH2         655.8  + 83.76         892.7 + 123.36           2.7        <0.15
                       (0.0 - 9416.6)         (0.0 - 7680.3)


        FORSH3        2251.7 + 163.34       1782.6 + 191.35            3.5        <0.10
                        (0.0 - 9254.0)      (0.0 - 10519.9)


        TFORSH        4128.8 + 226.83       4092.8 + 312.29           0.01         NS
                       (0.0 - 12571.4)      (0.0 - 14600.0)

        a - Mann-Whitney U test statistic












                                               41







                        as


         Model Im lementation/Land Classification
              Ph                      II







 "A










                                                  APPROACH


                 The land classification model developed during phase I of this project is a point-based

          model. That is to say that all of the parameters that were used in its development (even

          though some were area parameters) were focused on or determined by an individual point

          (either a nest location or randomly chosen point). Because of this, classification results apply

          to discrete points in space rather than, for example, to some area included in a polygon.

          However, the area within a polygon of interest could be classified by establishing a network

          of points across its surface and classifying each individually. The set of classification values

          obtained would give a collective representation of not only the average habitat quality within

          the polygon as a whole but also the spatial arrangement of habitat categories across its

          surface. Assuming that the model used gives a reasonable representation of habitat quality,

          how well the set of points reveals the true habitat value within the polygon depends on the

          resolution of the point network. A progressive increase in the number of points within the

          network (i.e. reducing the space between points) would theoretically lead to a nearly

          continuous view of habitat quality. This was the approach used to implement the model in

          phase IL

                 The model was implemented within two demonstration areas including: 1) a 100 mi.

          reach of the James River, 2) a 75 mi. reach of the Rappahannock River. The working area

          surrounding these two drainages and their tributaries was considered to be all lands that were

          within 3 kin of a channel that was at least 250 m wide (this is taken from the first constraint

          of the final model, see Figure 12 of phase I above). Once the working area was delineated,

          a network of coded, registration points was established across its surface. The network was
  4



                                                       42









          constructed with 400 m spacing between points. This level of resolution was used because it

          1) provided considerable overlap in area measurements (thus providing a good level of

          redundancy across the working area), 2) resulted in a manageable number of points to be

          parameterized, and 3) provided low enough resolution such that classification results could be

          presented on an entire drainage map of reasonable size.




                                                   METHODS


                 Just as in the delineation of the working area for the selection of random points in

          phase I above, the first model constraint (see Figure 12 above) was used to determine the

          working area within the demonstration areas. All lands surrounding the two major drainages

          and their tributaries that were within 3 Ian of a channel measuring at least 250 wide were

          considered to be within the working area. This land mass was delineated on topographic

          maps by beginning at the respective river mouths and measuring outward from the shorelines

          to 3 km. By moving along appropriate shorelines, the outer boundary of the working area

          was penciled in. The buffer zones created in this way silhouetted the drainages to a point at

          which channel widths were approximately 250 m wide where they were rounded and closed

          off. Major tributaries off the rivers were treated in a similar fashion. This procedure

          resulted in the delineation of a working area on the James that extended up from the mouth

          to Drewry's Bluff and included three major tributaries (the Nansemond, the Pagan, and the

          Chickahominy Rivers). The Rappahannock River was followed to Spotsylvania and included

          just one major tributary (the Corrotoman River). In total 51, 7.5 minute topographic maps

          were used to cover the two river systems (Appendix 1).



                                                        43








                 After working areas on both drainages had been delineated, a network of registration

          points was established. The network was established over the entire surface using a large

          acetate template. The template was composed of 30 rows of 50 small holes in a grid pattern

          such that holes were separated by 400 m on a 1:24000 scale topographic map. Beginning at

          the mouth, topographic maps were aligned and taped together at the seems before registration

          points were marked. The template was large enough that three topographic maps could be

          marked before having to realign. After the entire working area had been marked, each point

          received an individualized alpha-numeric code. A total of 8091 registration points were fixed

          within the James River working area and 7293 within the Rappahannock area.

                 Registration points were classified by first testing them for compliance with model

          constraints 2 - 4 (see Figure 12 above). Compliance with constraints was assessed quickly

          using a transparency with a central point surrounded by two circles (with 200 and 400 m

          radii respectively). Points that violated any one of the following criteria: 1) < 5 houses

          within 200 m, 2) < 10 houses within 400 m, 3) any mature forest cover within 200 in were

          considered to be unsuitable and no further measurements were made.


                 Registration points that fell within the model constraints were retained for further

          measurements. Model variables were parameterized for each of these points and

          measurements were manipulated according to the model specifications to compute scores.

          Scores were then re-scaled using the Habitat Quality Equation and grouped into the following

          categories: questionable, useable, good, and very good. Descriptive statistics were computed

          for model variables and land classification results for each river system separately.





                                                         44









                 After land classification procedures were completed, a digital database was

          constructed for both the working area and the network of registration points using arcinfo.

          After a common coding system was developed, the land classification database was merged

          with the GIS database to display classification results on drainage maps.




                                                    RESULTS


          Land Area


                 The working area or buffer zone along the James River enclosed approximately 1,233

          km@ of land of which 458 kn@ (37. 1 %) did not meet the model constraints and so was

          considered unsuitable. The majority (85%) of this land was classified as unsuitable because

          building density was beyond the tolerance range (Figure 1). The buffer zone along the

          Rappahannock River encompassed approximately 1, 111 ktn@ of land of which only 274 Ian'

          (24.7%) were considered unsuitable. Not only does the Rappahannock appear to have

          relatively more suitable land compared to the James, a greater portion of the unsuitable land

          is due to the lack of nest trees when compared to the James. This is a clear indication of the

          agricultural character of the landscape along the shores of the Rappahannock.

          Model Variables


                 Descriptive statistics for the four model variables by classification category and river

          system are presented in Table 1. Relationships between the land classification categories and

          the model variables reflect the patterns in habitat quality detected during phase I analyses.

          The habitat quality rating for a given location is negatively influenced by distance from water

          and positively related to distance from sources of disturbance.



                                                        45






























      Figure 1. Summary of Unsuitable Categories.








                               Description of Unsuitable
                                               Categories

                   100                                             M James
                                                                   M Rappahannock

                     75                       . . . . . . . .



                     50

              CL


                                                                            .................
                     25



                       0
                                Housing Density               No Forest Cover

                                                 Constraints
                            mg.






































        Figure 1

                                                46









               Table 1. Mean closest distances, minimum and maximum distances
                                    for each variable by range for James and Rappahannock
                                    Rivers.


               RANGE CATEGORIES                                      CODE                           JAMES                         RAPPAHANNOCK
               Questionable                                               1                              991                                 1222
               Useable                                                    2                            1836                                  1980
               Good                                                       3                            2154                                  2246
               Very Good                                                  4                              103                                      44

               VARXABLE DXSTANCES XX METT"

                                                                   James                                           Rappahannock
                   VAR I RANGE                 MEAN         STDERR          MIN          MAX         MEAN           STDERR          MIN           MAX

                  DISCHI            1           789.6           15.6           0.0       2506.4          710.5          10.8           0.0        2144.9


                                    2           516.5            9.7           0.0       2337.7          445.5           7.1           0.0        2169.0


                                    3           295.5            6.8           0.0       2313.6          245.7           4.8           0.0        1711.1


                                    4           106.5           12.7           0.0         530.2          87.6          14.1           0.0        361.5




                  DISCH2            1          1816.4           25.1           0.0       3590.9          1796.2         22.0           24.1       3398.1


                                    2          1366.2           18.8           0.0       3639.1          1376.1         18.8           0.0        3542.7

                                    3           935.9           16.7           0.0       3446.3          1022.2         17.5           0.0        3374.0


                                    4           326.4           26.9           0.0       1638.8          237.2          29.8           0.0        747.1




                  DISSCR            1           149.9            4.7           0.0       1253.2          151.8           4.0           0.0        964.0


                                    2           320.8            5.3           0.0       1638.8          348.1           5.0           0.0        1903.9


                                    3           741.4            9.3           0.0       2626.9          800.9           8.7           0.0        2626.9


                                    4          1736.4           55.3        265.1        2992.0          1804.8         66.0          674.8       2795.6




                  DISBLD            1           200.8            4.3           0.0       1012.2          167.7           3.0           0.0        698.9


                                    2           379.2            4.8          24.1       1494.2          337.5           3.8           24.1       1132.7


                                    3           741.7            7.9          24.1       2385.9          625.6           5.9           24.1       2024.4


                                    4          1679.5           46.5        795.3        2771.5          1434.5         48.8          723.0       2144.9
















                                                                                   47








          Patterns and actual values were very consistent for both drainages.

          Habitat Quali1y

                 Habitat quality ratings from registration points that met the model constraints showed

          similar patterns for both river systems. The majority of points fell within the good range,

          followed by the useable, and questionable ranges (Table 2). For both rivers, a small number

          of points also fell into the very good range. A rough estimate of potential breeding habitat

          may be achieved by summing the area within the useable categories (i.e. useable, good, very

          good). The estimated total potential habitat remaining on the James River is 623 km' or

          51 % of the total area. This may be compared to 650 kn@ or 59 % for the Rappahannock

          River (see Figure 2 for summary of categories).

                 In order to display the spatial distribution of habitat categories, the working areas of

          both drainages were broken into sections. The resulting map plates are presented in

          Appendix Il of this section.





















                                                       48









       Table 2. Summary of Habitat Quality Ratings for James and
                  Rappahannock River Systems.


             Range                 James                  Rappahannock

        Habitat             N      Mean    STDERR       N      Mean   STDERR
        Suitability                 HQ                         HQ
           (range)                Rating                     Rating

        Questionable     991       15.81     .16    1222      15.16     .15
       -(0 < 22)
        Useable          1836      28.76     .09    1980      28.67     .08
         (>=22 < 35)

        Good             2154      46.21     .18    2246      44.78     .15
       -(>=35 <  68)
        Very Good        103       74.74     .58       44     73.37     .66
         (>=68 <=100)
        Constr. la       1682       n/a      n/a     676       n/a      n/a
        Constr. Ib       865        n/a      n/a     559       n/a      n/a
        Constr. 2        460        n/a      n/a     566       n/a      n/a




























                                          49































       Figure 2. Land Classification results of areas within buffer
                  zones of James and Rappahannock Rivers.





















 A









                                       JAMES RIVER (N=8091)

                         40

                w C>     30

                CU       20

               CC
                  LL.    10

                           0
                                          Cm       Ui      Uj
                                                   __j     -j
                                          cc       cm      W       C@
                                  co      Cn               Uj
                                                   0       CD
                                          C)
                                                   I---                     cc
                                                   W                        LU
                                                   Ui

                                                   C3

                               Rappahannock            River     (N=7293)
                         40

               w CA      30

               Cd        20

                                                                  ...........
                 LA-     10

                           0
                                                   LLJ     LU              Im
                                  Cr.     CC
                                                           -<      C9      C)
                                  U3      w                LU
                                                           co
                                          0
                                                                           cc
                                                   C03                     LU
                                                   LAJ

                                                   Ot


                                   CLASSIFICATION CATEGORY




        Figure 2

                                             50









       Appendix 1.  List of topographic maps used to collect data for
                    model implementation.

       James                     Rappahannock
       Newport News North        Deltaville
       Newport News South        Fleets Bay
       Bowers Hill               Irvington
       Chuckatuck                Lancaster
       Benns Church              Wilton
       Smithfield                Saluda
       Mulberry Island           Urbanna
       Yorktown                  Lively
       Bacons Castle             Church View
       Hog Island                Morattico
       Surry                     Dunnsville
       Claremont                 Haynesville
       Brandon                   Tappahannock
       Norge                     Montross
       Toano                     Mount Landing
       Walkers                   Champlain
       Providence Forge          Loretto
       Charles City              Supply
       Savedge                   Colonial Beach South
       Westover                  Rollins Fork
       Hopewell                  Port Royal
       Roxbury                   Rappahannock Academy
       Dutch Gap                 King George
       Chester                   Passapatanzy
       Drewry's Bluff            Guinea
                                 Fredericksburg























                                       51
































      Appendix II: Map plates representing habitat suitability for
                    breeding Bald Eagles for the James River.
                             Plates I - VI.



          JAMES @R I VER                                                        I

          HABITAT SUITABILITY FOR BREEDING EAGLES



                                        a am
                                     a   a
                                         a
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                               10.15 Raw      ama           a
                                 MR       a
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                                 a                         am a a       am
                                                                       man
                                    a a                     :mama        a
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                                             ::a
                               a ME          am
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                          amnam            am
                       0 Emma             mamm  a
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                       :
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                                         a
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                                   a aaa
                                     a

                             a a     a
                                   a

















                    0

                                          eat       I









                                                      N     LEGEND

                                                            w Unsuitable (Constr. 1)
                                                            a Unsuitable (Constr. 2)
                             LE K--T-                       6 Questionable Habitat
                            0.8 0 0.8 1.5 2.3 3Miles        13 Usable Habitat
                                                            6 Good Habitat




            JAMES RIVER

            HABITAT SUITABILITY FOR BREEDINC EACLES




                                                                   Chesapeake
                                                                          Bay





























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                      no a        a
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                                                               N       LEGEND

                                                                       N Unsuitable (Constr. 1)
                                                                       0 Unsuitable (Constr. 2)
                                                                       W Questionable Habitat
                                 0.8 0 0.8 1.5 2.3 3 Miles             E3 Usable Habitat
                                                                       S Good Habitdt



           JAMES RIVER                                                            III

           HABITAT SUITABILITY FOR BREEDING EAGLES









                                                              was a



                                Is                                a





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                                                                 LEGEND

                                                                 2 Unsuitable (Constr. 1)
                                                                 0 Unsuitable (Constr. 2)
                                Imm    I  I   I  1               8 Questionable Habitat
                               0.8 0 0.8 1.5 2.3 3Miles          0 Usable Habitat
                                                                 9 Good Habitat



          JAMES RIVER                                                        IV

          HABITAT SUITABILITY FOR BREEDINC EACLES




                                0110=2
                                      a
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                                           0:
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                         101010
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                                  an                   No
                      a                                MEN
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                     a   an   a       N:mmna                           a
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                            an    an    man      ME           MU.mMM =011010
                            a                          an an
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                                                                 own No:
                              :a         a a           no   a a: own
                                            a          a     a
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                                                       N   LEGEND

                                                           6 Unsuitable (Constr. 1)
                                                           9 Unsuitable (Constr. 2)
                                                           2 Questionable Habitat
                            0.8 0 0.8 1.5 2.3 3 Miles      0 Usable Habitat
                                                           0 Good Habitat



        JAMES RIVER                                             v

        HABITAT SUITABILITY FOR BREEDING EAGLES

















                a as


                ONE  a  son
                a a  a a am
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                        an  a 0 a                       a
                     no so          a               anon M:M
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              A2N
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                                                LEGEND

                                                0 Unsuitable (Constr. 1)
                                                N Unsuitable (Constr. 2)
                                                6 Questionable Habitat
                      0.8 0 0.8 1.5 2.3 3miles  0 Usable Habitat
                                                0 Good Habitat




            JAMES RIVER                                                               vi

           HABITAT SUITABILITY FOR BREEDING EAGLES



                                                                       GPM


















                                                         a
                                                            a
                                                             a




                                                             now



                                                   a
                                                                   m:m
                                               man            M:m loan "
                                              NEWS 0                            0
                                               Son              no a=           Oman
                                               OEM             :Nam a           an
                                               a an a  Mason   unman            a
                                                       am      as      an       a
                                                                a      OEM
                                                       Oman        0        no
                                                            a       OWS
                                                                      41111::   mom
                                                          an a
                                                          a                SO=
                                                                am UNNE         MOORE
                                                          am
                                                          an                    Mamma
                                                        0                       so
                                                                            am     41:
                                                         a        mass   a      aa 0:

                                                          a                        Not
                                                                nomm@              a 9
                                                                 man a          a: at
                                                                  0             0
                                                                                ONES
                                                                          mons'o
                                                                      a         mom
                                                                       a        ggelan
                                                                      no
                                                                      No        a: an
                                                                                am aa
                                                                                Saoa
                                                                                a  0
                                                                           on a
                                                                                a








                                                                   LEGEND

                                                                  0 Unsuitable (Constr. 1)
                                                                  B Unsultablo (Constr. 2)
                                L"     F- 17-71=1                 9 Questionable Habitat
                               0.8 0 0.8 1.5 2.3 3 Miles          0 Usable Habitat
                                                                  9 Good Habitat


































      Appendix II:  --- continued ---
                    Map plates representing habitat suitability for
                    breeding Bald Eagles for the Rappahannock River.
                             Plates I - V.

















 I




      RAPPAHANNOCK RIVER
      HABITAT SUITABILITY FOR BREEDING EAGLES

        J











             Emm-
            a     go MUM
                son      so
           01110         man     a
                              a
                a 0  Me 13:     MEN
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         Raw MM       an won
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                                  0  a
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        a MANa   a       a
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                         amm  a
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                                     pt



                                              N   LEGEND
                                                  0Unsuitable (Constr. 1)
                         1311CE-1                 NUnsuitable (Constr. 2)
                         1    01 2   3 4 Miles    a(laostionable Habitat
                                                  0 Usable Habitat
                                                  aGood Habitat



        R A PPA.HA NN 0 CK                             R I VER                               II

        HABITAT            SUITABILITY                FOR BREEDING EAGLES

                                                          M




                                                              MEMO 10--
                          0                 a 01:01            no     -       man
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                                                                                          Mw,,M I
                                                                               0  ME=












                                                                  N     LEGEND

                                                                        8 Unsuitable (Constr. 1)
                                  L M M     I   I    1                  8 Unsuitable (Constr. 2)
                                       0  1    2   3    4 Miles         0 Questionable Nobltdt
                                                                        0 Usable Habitat
                                                                        N good Habitat




        RAPPAHANNOCK RIVER                                                           III

        HABITAT SUITABILITY FOR BREEDING EAGLES























           -.)a 0  a
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            a          Man
            a on   no   . a
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                                                              N     LEGEND

                                                                    E Unsuitable (Constr. 1)
                                                                    0 Unsuitable (Constr. 2)
                               1    0  1    2   3    4 Miles        E Questionable Habitat
                                                                    0 Usable Habitat
                                                                    a Good Habitat




        RAPPAHANNOCK RIVER                                                                  IV

        HABITAT SUITABILITY FOR BREEDING EAGLES




          was :1010    a     0
                  2    0                                                           cb.
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            M=
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                                         -i-       I AM,    MS.            am Is
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                                                                     VIS       a             NJ
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                                                                       T          Is  M   as
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                                                                                       M



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                                                                                             Is



                                                                 N     LEGEND

                                                                       0 Unsuitable (Constr. 1)
                                                                       0 Unsuitable (Constr. 2)
                                 1    0  1    2    3   4 Miles         19 Questionable Habitat
                                                                       * Usable Habitat
                                                                       * Good Habitat



           RAPPAHANNOCK RIVER                                                                                                 v

           HABITAT SUITABILITY FOR BREEDING EAGLES















                                        0 a

                                a                                    =a                                 a
                                                        a                  a
                                            -a  a a     a               a a        us                   mom a
                               am a           a =a                                                      anus
                                 an a                                                                     Eno      0
                                    a                                                                         : .0
                                                   0                      am        mom         0                a a
                                                        a             a                         0a"
                                                Room                                   .   ":::                    a
                                                                                            va
                                                                               a             as             a
                                                   0          NNE                               a          a       a
                                                              a                                           on
                                                                             an                         am
                                                                                            ME          'Oman        an
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                                                                                                                    a.,
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                                                                                                                       a



                                                                                                                   man



                                                                                                                     an
                                                                                                                             a
                                                                                                                             a







                                                                                      N         LEGEND
                       IV
                                                                                                8 Unsuitable (Constr. 1)
                                              IS IS      I     I     1                          0 Unsuitable (Constr. 2)
                                                                                                0 Questionable Habitat
                                                   0    1    2     3      4  Miles              ElGood Habitat
                         L                                                                      E3 Usable H4bl tat



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