Wildlife Management: Issues Concerning the Management of Bison and Elk
Herds in Yellowstone National Park (Testimony, 07/10/97,
GAO/T-RCED-97-200).
Yellowstone National Park, with about 2.2 million acres of land and the
largest concentration of free-roaming wildlife in the lower 48 states,
is considered the "crown jewel" of the national park system. This
testimony focuses on (1) the National Park Service's current policy for
managing free-roaming bison and elk in Yellowstone, (2) the controversy
surrounding the impact of these herds on the park's rangeland and
riparian areas, and (3) the controversy surrounding the health risks to
domestic livestock posed by exposure to diseased bison and elk.
--------------------------- Indexing Terms -----------------------------
REPORTNUM: T-RCED-97-200
TITLE: Wildlife Management: Issues Concerning the Management of
Bison and Elk Herds in Yellowstone National Park
DATE: 07/10/97
SUBJECT: Wildlife management
Cattle
National parks
Range management
Grazing rights
National forests
Infectious diseases
Federal/state relations
Forest management
Interagency relations
IDENTIFIER: Yellowstone National Park (WY)
Wyoming
Montana
USDA Brucellosis Eradication Program
Idaho
Grand Teton National Park (WY)
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Cover
================================================================ COVER
Before the Subcommittee on National Parks, Historic Preservation and
Recreation, Committee on Energy and Natural Resources, U.S. Senate
For Release
on Delivery
Expected at
2 p.m. EDT
Thursday
July 10, 1997
WILDLIFE MANAGEMENT - ISSUES
CONCERNING THE MANAGEMENT OF BISON
AND ELK HERDS IN YELLOWSTONE
NATIONAL PARK
Statement of Victor S. Rezendes, Director,
Energy, Resources, and Science Issues,
Resources, Community, and Economic
Development Division
GAO/T-RCED-97-200
GAO/RCED-97-200T
(141012)
Abbreviations
=============================================================== ABBREV
BLM -
APHIS -
EIS -
============================================================ Chapter 0
Mr. Chairman and Members of the Subcommittee:
We are pleased to be here today to provide you with the results of
the work that we performed at your request on wildlife management
issues at Yellowstone National Park. As you know, Mr. Chairman,
Yellowstone is the world's first national park. It is considered the
"crown jewel" of our National Park System, with about 2.2 million
acres of land, over 3 million visitors in 1996, and the largest
concentration of free-roaming wildlife in the lower 48 states. The
controversy over the impact of these free-roaming animals, especially
the bison and elk herds, as well as their health, is the subject of
our remarks today. Specifically, our testimony will focus on (1) the
National Park Service's current policy for managing free-roaming
bison and elk in Yellowstone, (2) the controversy surrounding the
impact of these herds on the park's rangeland and riparian areas, and
(3) the controversy surrounding the risks to domestic livestock posed
by exposure to diseased bison and elk. As you know, Mr. Chairman,
interested parties hold widely divergent views on these issues.
In summary, we found that current laws and regulations provide park
managers with broad discretion on how to manage their park's
resources. As a result, parks with similar wildlife resources, such
as Yellowstone and the neighboring Grand Teton National Park, can
apply different approaches to managing these resources. While
Yellowstone uses "natural regulation"--a policy that allows natural
forces, such as climate, food supply, and predation--to regulate the
size of its bison and elk herds, Grand Teton has established specific
goals and objectives to control the size of its bison herd.
Critics of Yellowstone's natural regulation management
policy--including some scientists, state officials, and
representatives of livestock interests--believe that the policy's
implementation has produced bison and elk herds that are too large
and damage the park. In their view, the park's rangelands are being
overgrazed; the riparian areas are being damaged; and because these
lands are being depleted, bison and elk are migrating from the park
in search of forage on private lands and public grazing areas.
According to the Park Service's recently published studies, however,
researchers have found that Yellowstone's grasslands are not
overgrazed, and several factors, such as climate, fire, and a lack of
predators, have contributed to the decline of the range and of the
riparian areas' woody vegetation. In addition, park officials
believe that bison are leaving the park for a combination of reasons.
Specifically, these animals are nomadic by nature; they do not have
access to sufficient forage during harsh winters, such as that of
1996-97; and, except in the northern range area, they can follow
snowmobile trails out of the park. In addition, by allowing bison to
avoid deep snow and thus conserve energy, snowmobile trails may also
contribute to the growth in their numbers.
The health of Yellowstone's bison and elk herds is a major concern
for livestock owners and public officials in the states bordering the
park. Because many Yellowstone bison and elk are infected with
brucellosis--a disease that can cause cattle to abort during
pregnancy--these parties fear that the wild animals may transmit the
disease to domestic cattle. A state with infected livestock may lose
its federal brucellosis-free classification, jeopardizing its right
to freely transport cattle across state lines. As a result, these
parties believe that the risk of transmitting brucellosis from bison
to domestic cattle must be eliminated by containing bison within the
park, by using vaccines, or by shooting or capturing bison that leave
the park. Because elk have a lower rate of infection than bison, the
states currently differ in the methods they use to manage the disease
in elk. However, according to the Park Service, the risk that
brucellosis will be transmitted from either elk or bison to cattle is
likely to be very low, and no such transmission in a wild,
uncontrolled setting has been verified in the scientific literature.
Furthermore, park officials maintain that existing vaccines have not
been proven effective for bison and elk. Both the park and its
critics have scientific evidence to support their positions. This
past winter, the Yellowstone bison herd was reduced to about a half
of its size the previous year. In the short term, this reduction may
provide an opportunity for the Park Service and its critics to
complete and assess the results of studies, potentially going a long
way toward resolving this controversy.
BACKGROUND
---------------------------------------------------------- Chapter 0:1
Yellowstone was created by an act of Congress in 1872 as a public
park for the benefit and enjoyment of the people and for the
preservation and retention of its resources in their natural
condition. Yellowstone's mandate, creating a dual mission to
preserve natural resources while providing for the public's enjoyment
of them, has served as a model for the rest of the park system and
for parks around the world.
Yellowstone is at the center of approximately 20 million acres of
land, commonly called the Greater Yellowstone Area or ecosystem.
These lands are managed by four different federal agencies--the
National Park Service, the Forest Service, the Fish and Wildlife
Service, and the Bureau of Land Management (BLM); three different
states--Idaho, Montana, and Wyoming; and numerous private land
holders.
The Park Service manages bison and elk only within Yellowstone.
Outside the park, the neighboring states of Idaho, Montana, and
Wyoming manage wildlife not only on their own lands but also on BLM
and Forest Service lands. Although the Forest Service manages
wildlife habitat on its lands, the states manage the wildlife. For
example, in Gallatin National Forest, the Forest Service manages
wildlife habitat, while the Montana Department of Fish, Wildlife, and
Parks manages wildlife within the forest's borders. The Fish and
Wildlife Service manages wildlife refuges, such as the National Elk
Refuge south of Yellowstone, and the Bureau of Land Management
manages land used by both wildlife and cattle in the Greater
Yellowstone Area.
This past winter, park officials estimated the size of the northern
elk herd at about 17,000 in Yellowstone and the total number of elk
in the Greater Yellowstone Area\1 at about 120,000. The population
of Yellowstone's northern range elk herd has ranged between 16,000
and 20,000 since 1991. At the beginning of this past winter, about
3,500 bison lived within the park, 900 of which occupied the northern
range. Subsequently, about 1,100 bison left the park and were shot
or shipped to slaughter because of concerns about brucellosis. About
700 other bison were killed by the severe winter, leaving
approximately 1,700 bison in the park this spring, including about
300 in the northern range.
For thousands of years, various animal species have routinely
migrated in and out of what is now Yellowstone National Park. Bison
and elk herds seasonally migrate out of the park to seek forage,
especially in severe winters like that of 1996-97. While elk have
traditionally migrated widely in the Greater Yellowstone Area, bison
have more recently left the park, primarily through its northern and
western borders, to seek available winter range. Appendix I
illustrates the Greater Yellowstone Area elk herds' winter ranges and
migration routes. Appendix II illustrates the Greater Yellowstone
Area bison herds' winter ranges and migration routes .
Because bison that migrate outside Yellowstone may be infected with
brucellosis and may interact or share rangeland with domestic cattle,
the U.S. Department of Agriculture's Animal and Plant Health
Inspection Service (APHIS) and its state counterparts also have a
strong interest in the management of Yellowstone's wildlife. APHIS
is responsible for eradicating brucellosis from cattle in the United
States. According to APHIS, it also has statutory authority to
eradicate brucellosis in all animals--including bison. Since a
national brucellosis control program was first instituted in 1934,
more than $3.5 billion in federal, state, and industry funds have
been spent trying to eradicate the disease. According to APHIS,
nationwide, only 22 herds of domestic cattle and bison are now known
to be infected. The states also play a major role in the effort to
eradicate brucellosis. Because federal statutes on controlling
disease in livestock pre-empt the states' authority only when cattle
and bison are moving in interstate commerce, most states have enacted
their own statutes to supplement federal regulatory efforts.
The Brucella abortus organism, a bacterium, is transmitted among
animals primarily through exposure to infected reproductive material,
such as aborted fetuses. APHIS tests cattle and bison for antibodies
to the Brucella abortus organism. Antibodies in blood samples may
indicate either past exposure to the disease or current infection.
Positive tissue cultures for Brucella abortus confirm the presence of
live bacteria and the potential for animals to be infectious.
However, according to APHIS, negative tissue cultures do not prove
the absence of bacteria because the organism cannot always be
isolated even when it is present. After surveillance tests and
procedures are conducted to ensure that cattle and bison herds are
free of the disease, APHIS may certify states as brucellosis-free.
This certification allows the states to ship their cattle and bison
in interstate commerce without having to perform expensive testing to
assure importing states that the cattle or bison do not pose a threat
of the disease to their livestock industry. As of June 1997, Idaho,
Montana, Wyoming, and 34 other states were certified as
brucellosis-free.
The economic consequences of infection with brucellosis could be
significant. Under the requirements of APHIS' eradication program,
if a single herd of cattle or bison in a state that is designated
brucellosis-free becomes infected, the infected animals must be
slaughtered, the herd quarantined, and the herds in the surrounding
area tested to ensure that the disease has not spread. If the herd
is slaughtered and no additional infection is found, the state can
remain classified as brucellosis-free. If the herd is not
slaughtered or additional infection is found, the state's
classification will be lowered and additional interstate testing
requirements implemented. Montana estimates that it saves between $1
million and $2 million annually because it does not have to test
cattle for brucellosis. A state with infected cattle or bison may
also be subject to restrictions imposed by other states. For
example, because of the increased movement of brucellosis-infected
and -exposed bison out of the Greater Yellowstone Area, the state of
Oregon decided in March 1997 to protect the interests of its cattle
industry by immediately requiring the testing of any cattle entering
Oregon from Montana or Wyoming. Other states have imposed, or
threatened to impose, similar restrictions.
--------------------
\1 The area includes Yellowstone and Grand Teton national parks and
six national forests: Beaverhead-Deerlodge, Bridger-Teton, Custer,
Gallatin, Shoshone, and Targhee.
YELLOWSTONE'S WILDLIFE
MANAGEMENT POLICY
---------------------------------------------------------- Chapter 0:2
The management of Yellowstone's wildlife, especially of bison and
elk, has gone through many phases as wildlife managers have gained
experience and scientific knowledge has grown. When the park was
founded in 1872, there were numerous elk, estimated at 25,000 in
1891, and, according to park officials, bison were also very common.
However, no estimates of the bison population exist for that period.
After almost two decades of slaughter by market hunters, the bison
population in Yellowstone dwindled to about 44 in 1901-02.
Yellowstone officials saved the bison from extinction by aggressively
protecting the remnant population and supplementing it with bison
imported from Montana and Texas. For several decades, Yellowstone
also aggressively reduced the populations of wolves and other
predators. As a result, the park's bison population gradually
increased, growing to more than 1,000 in 1930. However, from about
1935 to 1968, park rangers controlled the elk and bison populations
by shooting or by trapping and removing animals. This "culling
program" reflected the then-prevailing view that wildlife populations
had to be controlled to meet an area's carrying capacity--a
determination of how many animals can live in an area without
degrading the range. In the early 1960s, however, elk kills
initiated by park officials to reduce the size of a herd that was
considered too large, led to a public outcry, studies, and U. S.
Senate hearings on Yellowstone's wildlife management policy. As a
result, in the late 1960s, Yellowstone's wildlife management policy
changed significantly. According to park staff, although little
information was available on how functioning elk and bison
populations might respond in a natural environment, park managers
thought that Yellowstone might be a place to develop this knowledge
and resolve the controversy over the size of the herds by letting
natural forces regulate the populations. Therefore, in Yellowstone,
natural regulation replaced the capture and culling of elk and bison
herds.
The park's master plan, written in 1974, reflects the shift to
natural regulation, stating that "Yellowstone should be a place where
all the resources in a wild land environment are subject to minimal
management". For wildlife, the plan proposes to reduce or eliminate
disruptive human influences, relying, whenever possible, upon natural
controls to regulate animal numbers. For the past 30 years, the Park
Service has been implementing natural regulation in Yellowstone, in
essence, following the park's master plan. However, the Park Service
recognizes that because of the pervasiveness of human influences in
today's world, true natural process management is seldom feasible.
In the lower 48 states, the Park Service believes that Yellowstone is
the only park large enough to test the effects of natural regulation.
At Yellowstone today, the Park Service relies on natural forces
within the park--mainly animal behavior, climate, food supply, and
predation--to regulate bison and elk populations. In addition, elk
have always been hunted in the surrounding states. More recently,
bison have been killed when they have migrated out of the park, and
some public hunting of bison has occurred in both Wyoming and
Montana. However, in 1991, Montana discontinued public hunting.
According to park officials, once humans stopped controlling the size
of the herds and Yellowstone adopted the natural regulation policy,
the bison and elk populations increased considerably. For example,
from 1967 to 1988, the bison population rose from 397 to more than
2,500 and then peaked at about 4,200 in the summer of 1994.
Yellowstone's elk population grew about sixfold, from 3,200 in 1968
to about 19,000 in 1994. Park officials point out that without human
intervention, the low bison and elk populations of the 1960s would
not have occurred. They stated that these low numbers were achieved
only by large-scale reductions involving the slaughter of thousands
of animals each year. In addition, park officials noted that a key
predator, the wolf, was missing during this period. Wolves were
reintroduced to Yellowstone in 1995, and park officials believe time
is needed to determine their impact on the elk population.
Current laws and regulations give park managers broad discretion on
how to manage wildlife in the park. While an overall mandate of the
Park Service is to conserve wildlife, wildlife management policies
can vary from park to park, depending on the history of the park, the
enabling legislation, the neighboring land, and the local geography.
For example, Grand Teton National Park (330,000 acres), just south of
Yellowstone (2.2 million acres), has a different mandate, history,
neighbors, and geography and has adopted a different policy for
managing bison and elk. Grand Teton National Park's legislation
provides for hunting elk within portions of the park and for grazing
cattle--two uses that are not allowed in Yellowstone. Hunting gives
the park some direct control of elk populations, and the presence of
cattle adds management challenges and increases working relationships
with ranchers. The National Elk Refuge, which is adjacent to Grand
Teton, provides winter range and feed for both bison and elk, as do
22 feedgrounds operated by the state of Wyoming. However, feeding
these animals further complicates issues by concentrating their
populations and increasing the risk of disease transmission.
In Grand Teton National Park the bison herd grew from 16 in 1969 to
about 320 this past winter. Park officials said that at the
conclusion of this year's calving season, the bison herd will number
nearly 380. The growth of the herd has raised a number of management
concerns, including questions about the need to set specific
objectives for the herd's size. Grand Teton's draft management plan
states that the park could maintain a free-roaming herd of about
200-250 bison without jeopardizing the genetic viability of the herd.
However, park officials say they are considering public comments on
the draft suggesting that the herd should be maintained at 400
animals. To sustain the herd at the levels suggested, the park has
considered alternative management measures, which we discuss at the
end of this statement.
THE CONTROVERSY OVER THE IMPACT
OF BISON AND ELK HERDS ON
YELLOWSTONE'S RANGE AND
RIPARIAN AREAS
---------------------------------------------------------- Chapter 0:3
The condition of Yellowstone's northern range\2 has concerned the
public, land managers, and scientists for more than 70 years.
Critics of the Park Service's wildlife management policies--including
some scientists, state officials, and representatives of livestock
interests--believe large populations of elk and bison have overgrazed
Yellowstone's available grasses and, in some cases, destroyed grasses
that were once natural to the northern range. They contend that many
of the natural grasses have been replaced by nonnative agricultural
grasses that better withstand heavy use by wildlife. In addition,
critics say that the large elk and bison herds have damaged riparian
areas. For example, the critics often cite declines in woody
vegetation, especially willows, aspens, and several species of
sagebrush in the Lamar Valley of the northern range, as indications
of the herds' negative impact on riparian areas. The critics contend
that the destruction of the willows and aspens has reduced beaver
populations and accelerated soil erosion in streambeds. Finally, the
critics maintain that the bison herds have grown so large that they
are naturally migrating out of Yellowstone in search of forage that
is no longer available in the park because of overgrazing.
According to the Park Service's recently published compilation of 28
reports on research studies of the northern range, Yellowstone's
grasslands do not appear to be overgrazed by any definition of
overgrazing.\3 The studies were conducted during a 6-year period that
began in 1986 and concluded in 1991. The studies were researched and
written by a variety of scientists from several universities and
agencies. The researchers found that the production of grasses
either was not reduced or was enhanced by the grazing of ungulates
(hoofed animals) in all but drought years. The research shows that
the decline in the range and riparian areas' vegetation was due to a
number of factors, including changing climatic conditions as well as
grazing by elk. According to park staff, the riparian plants are
smaller in size but in no danger of disappearing. Furthermore, the
park report states the supposed declines in beaver and white-tailed
deer populations were based on inaccurate historical interpretations.
Park officials point out that beaver populations persist in low
levels on the northern range, while larger colonies live in suitable
habitat elsewhere in the park.
Park officials do not attribute the migration of bison out of the
park to overpopulation but to a combination of factors. First, bison
migrate because they are nomadic. Second, severe winter conditions
can make forage inaccessible beneath deep snow and ice, forcing bison
to search for forage elsewhere. Finally, park officials point out
that except in the northern range, Yellowstone has "groomed" or
packed the snow on roads for snowmobiling in the park since the early
1970s. These trails facilitate the migration of bison out of the
park and enable the animals to conserve a great deal of energy by
avoiding travel through deep snow. Park officials said that access
to more winter range for bison outside the park would enhance their
chances of survival in severe winters, but opponents think that the
herds should be reduced to numbers that can be supported within the
park. The park is currently reevaluating its policies on the use of
snowmobiles because of their effects on the environment and wildlife.
Both supporters and critics of the Park Service's policies have
scientific evidence that supports their points of view. For example,
the 6-year study of the northern range addressed the population
dynamics and ecological effects of elk, bison, moose, deer, and other
ungulates on the soil, vegetation, and watersheds of the northern
range. The research found that the bunchgrass, swale, and sagebrush
grasslands of the northern range did not appear to be overgrazed. In
riparian areas, willows were much taller in some parts of the
northern range in the late 1800s than currently, and virtually no
aspen have reached tree height since the 1930s. A study of
historical aspen growth found that there was only one period, between
about 1870 and 1895, when young aspen were not eaten by ungulates and
grew as tall as trees on the northern range. According to the park's
summary report,\4 the discovery that aspen reached full height during
only one period in the park's history suggests that the failure of
aspen to grow into trees should not be regarded as proof that elk are
overabundant. Rather, the summary continued, several factors are
involved in aspen growth, including the number of elk, changes in
climate, dry or wet weather, fires, and the number of predators
feeding on elk. Park officials have called for more research on
woody vegetation.
Critics of Yellowstone's wildlife management policy disagree that
factors other than wildlife grazing are to any significant degree
responsible for the lack of robust woody vegetation on the northern
range. They contend the research program undertaken by the Park
Service did not look for evidence of overgrazing and was incomplete.
They maintain, for example, that park scientists have not documented
a cause-and-effect relationship between climate and the decline of
willows. In addition, some critics assert that independent research
on range and riparian areas in the park has been restricted by the
park, which controls funding for research and access to the park.
For example, in February 1997, a researcher with the Biological
Resources Division of the U.S. Geological Survey testified before
the House Subcommittee on National Parks and Public Lands that the
park would not approve or fund his proposed research on woody
vegetation in the northern range or grant him a permit to work in the
park. Park officials said they denied the work assignment because of
concerns over the research design and the relevancy of the proposal
to the work priorities of both the park and the Biological Resources
Division--then known as the National Biological Service.
To support their position, critics often cite a 1990 dissertation by
a Utah State University researcher that linked the decline of
riparian vegetation directly to growth in the elk population. Park
officials, however, state that this study was based on a number of
key assumptions about conditions in the park during pre-European
times. Park officials say they disagree with the researcher on
issues such as the number of Native Americans that lived in
Yellowstone and the impact they had on wildlife. Park officials
added, however, that there is no scientific evidence available on
either issue.
Critics familiar with the principles of commercial range management
for the production of livestock believe that the number of grazing
animals in Yellowstone should be reduced to balance the available
forage. They cite a 1963 survey of Yellowstone's northern range
conducted by what was then the U.S. Department of Agriculture's Soil
Conservation Service. This survey concluded that the range could
support no more than 5,000 elk and 350 bison. According to the
survey, populations of bison and elk in excess of these numbers would
cause severe damage to the range and riparian areas. However, park
officials said that the 1963 survey used commercial standards for
domestic livestock to assess the park's carrying capacity. According
to park officials, they and other leading wildland ecologists believe
these standards should not be applied to wildlife.
A Forest Service official at Gallatin National Forest, which borders
Yellowstone on the north and west sides of the park, also believes
that a commercial carrying capacity cannot be set for wildlife.
According to this official, Gallatin National Forest does not develop
carrying capacity limits for wildlife because the Forest Service
cannot control when wildlife come or go on the land. Gallatin
National Forest does develop carrying capacity limits for cattle
because the Forest Service can control where and when cattle graze on
its land. The official noted that cattle use only that portion of
the forage that is not required to support wildlife.
To help resolve the rangeland controversy, the House Committee on
Appropriations, in its July 1997 Committee Report on Interior's 1998
appropriation, directs the Park Service to initiate a review by the
National Academy of Sciences of all available science related to the
management of ungulates and their ecological effects on the rangeland
of Yellowstone.
--------------------
\2 The northern range includes the valleys of the Lamar and
Yellowstone rivers.
\3 Effects of Grazing by Wild Ungulates in Yellowstone National Park,
Department of the Interior, National Park Service (Technical Report
NPS/NRYELL/NRTR/96-01, 1996).
\4 Yellowstone's Northern Range: Complexity and Change in a Wildland
Ecosystem, National Park Service, Yellowstone National Park (1997).
THE CONTROVERSY OVER THE RISK
OF TRANSMITTING BRUCELLOSIS
FROM BISON AND ELK TO CATTLE
---------------------------------------------------------- Chapter 0:4
The extent to which domestic cattle risk infection through exposure
to diseased bison and elk--either from mingling directly with
infected wild animals or from using rangeland where infected wild
animals have previously grazed--is the subject of intense controversy
between the Park Service, wildlife management agencies, wildlife
conservation groups, livestock interests, Native Americans, and
others. Yellowstone National Park, under its interpretation of
natural regulation, allows natural processes to control wildlife
populations and opposes efforts to manage wildlife in a way that
conflicts with natural regulation or restricts wild animals'
free-roaming nature. APHIS, however, is committed to eradicating
brucellosis in the United States and believes that wildlife should be
tested and, if infected, slaughtered to prevent the disease from
spreading further. APHIS maintains that the techniques developed
through its 63-year-old eradication program for domestic livestock
can be applied to eliminate brucellosis in wildlife.
In Yellowstone, blood tests indicate that 40 to 54 percent of the
bison and about 1.5 percent of the elk from the northern range carry
antibodies to Brucella abortus. Some of the elk from the northern
range migrate to Montana for the winter. Other elk migrate to
Wyoming for the winter and use the federal National Elk Refuge or the
state's 22 feedgrounds to supplement their food base. On average,
about 38 percent of the mature cow elk using the National Elk
Refuge's feedground have had positive blood tests for brucellosis
antibodies. Positive blood tests indicate that an animal is infected
with or has been exposed to brucellosis. On the one hand, a positive
test does not necessarily indicate that an animal is infectious; on
the other hand, a negative test does not exclude the possibility of
infection, because the blood of some animals that are infected does
not react positively to the test.
In addition to blood tests, tissue cultures are performed to detect
the presence of brucellosis. Although tissue cultures are a much
more reliable method of identifying active infection, they also will
not identify all infected animals. The rate of current infection as
determined by tissue cultures is always lower than the rate of
positive blood tests because Brucella abortus cannot always be
cultured from infected animals. For example, an ongoing analysis of
samples from 41 bison killed during the winter of 1996-97 showed that
the blood tests for 30 females were positive. For 18 of these 30,
tissue cultures have been completed and the results were positive for
only 7. According to Wyoming officials, research with elk have
suggested a higher correlation between positive blood tests and
positive tissue cultures.
According to Park Service officials, in the scientific literature,
there is no documentation of brucellosis transmission from elk or
bison to cattle in a wild, uncontrolled setting. Furthermore,
although the risk of such transmission has never been quantified, the
Park Service maintains that it is likely to be very low. Hence, park
officials believe that testing and slaughtering infected wildlife to
eradicate a potential source of infection for cattle is not necessary
in Yellowstone and could result in the unnecessary slaughter of bison
and negatively affect the genetic viability of the herd. Park
officials also object to the use of vaccines that were developed and
tested for cattle but have not been proven effective for bison. They
contend that the untested vaccines may be ineffective and/or unsafe
for the herds and other wildlife that may come into contact with
them. Park officials also question whether the disease can be
eliminated from wildlife. For example, they note that the disease
may be impossible to eliminate from bison because elk and other
mammals can carry brucellosis, which could then find its way back
into bison. Unless brucellosis is eliminated from all of these
mammals, park officials and others have stated, some chance remains
that the disease will be transmitted back to the bison.
According to APHIS officials, in several cases of brucellosis, wild
elk or bison have been identified as the source of transmission.
These officials believe that any risk is unacceptable in an
eradication program. In addition, they refer to several other parks
where the disease has been eliminated from bison and elk. However,
APHIS officials agree that vaccines need to be tested and proven to
be safe and effective before being used on elk and bison.
During our review, we visited two of the three states that surround
the park--Montana and Wyoming. Both states are concerned about the
potential for the transmission of brucellosis between wildlife and
cattle. However, each state approaches this problem differently.
For example, the state veterinarian in Montana believes that no risk
is acceptable because transmission would threaten the states'
brucellosis-free certification from APHIS. In December 1994, APHIS
wrote a letter to Montana setting forth its intention to downgrade
the brucellosis-free classification of the state if the state failed
to take action against bison within its borders that were known to be
infected with or had been exposed to the disease. As a result,
Montana officials believe that they have no alternative but to
slaughter bison that move into the state. Montana officials stated
that they are not addressing the disease in elk because the rate of
infection in elk is low. In the long term, Montana officials said,
they plan to take action to eradicate the disease in elk. Wyoming,
which has fewer bison than Montana but a much higher incidence of
brucellosis in elk, has tried to manage the risks of exposure to the
disease while implementing a long-term program to eradicate it. For
example, in the Jackson area, Wyoming has worked with federal
agencies and private landowners to develop policies for separating
cattle from bison and elk to minimize the risk of transmission.
Also, many of the ranchers in the Jackson area voluntarily vaccinate
their cattle.
Both Montana and Wyoming officials believe that the vaccines they
have used successfully with domestic cattle could be applied to the
park's bison and elk herds. They and APHIS noted that the vaccine,
combined with efforts to test and slaughter infected animals, has
been used successfully on bison herds on private and other public
lands. Finally, some experts believe that even if brucellosis
remains in "other mammals," the disease would naturally decline and
be eliminated from other wildlife because the carriers would not be
able to transmit it to other animals.
Scientific data on both sides of the brucellosis debate are limited.
According to the Park Service, neither it nor APHIS has performed or
sponsored many scientific studies on the transmission of brucellosis
among elk and bison or on the development of vaccines against the
disease. Recently, however, the park, APHIS, and others have
initiated an ambitious series of studies on brucellosis in bison to
obtain answers needed for making future management decisions.
Critics of the park's position on brucellosis derive support for
their views from the biological similarities between bison and cattle
and data developed through APHIS' program for eradicating the disease
in domestic livestock, including bison. Some critics do not believe
that they are responsible for conducting additional research on
brucellosis in wild bison. However, since the late 1970s, Wyoming,
with technical and financial assistance from APHIS, has sponsored a
number of studies on the disease in elk. For example, the state
sponsored research to determine the effectiveness of a reduced dosage
of one type of cattle vaccine in elk and is testing the effectiveness
of injecting the vaccine through the use of a "biobullet" shot from
an air gun.
CURRENT EFFORTS TO CONTROL
BRUCELLOSIS
-------------------------------------------------------- Chapter 0:4.1
Various federal, state, and private groups are conducting many
research studies and planning efforts to control or eradicate
brucellosis in Yellowstone wildlife. In discussing the controversy
surrounding this issue, one official described it as a war. Another
official stated that the federal and state representatives are so
entrenched in their positions that no one wants to be the first to
compromise. He added that meetings on this issue have become so
heated that a fight once broke out between participants.
Recognizing the need to coordinate the work on brucellosis in the
region, in July 1995, the states and responsible federal agencies
established the Greater Yellowstone Interagency Brucellosis
Committee. This interagency committee includes representatives of
the states surrounding the park, the four federal land management
agencies, and APHIS. The committee has agreed on the objective of
planning for the elimination of brucellosis by the year 2010.
However, the states and agencies disagree on the current feasibility
of eliminating the disease, the actions needed to eliminate it, and
the effect of the disease on wildlife or on the livestock industry if
it is not eliminated. Although members are generally very supportive
of the committee's efforts, they agree that achieving results has
been difficult even when issues are generally agreed upon. For
example, a paper summarizing generally accepted information on
brucellosis underwent 12 revisions over 22 months before it received
final approval.
Despite these difficulties, members of the interagency committee
believe they are slowly making strides towards coordinating policies
and addressing scientific data needs. For example, the committee has
completed a policy on elk feedgrounds, produced an informational
report on the potential for brucellosis transmission by bull bison,
developed a bison quarantine protocol, and conducted a national
symposium on brucellosis in the Greater Yellowstone Area. Among its
current activities, the committee is coordinating a joint effort by
the park, the state of Montana, APHIS, and the Forest Service, as
well as three cooperative efforts in Wyoming.
Since 1989, Montana and the Park Service have been meeting to develop
a long-term plan for managing the brucellosis-exposed, free-roaming
bison that move primarily during the winter from the park to public
and private lands in Montana along the northern and western
boundaries of the park. The first goal of this effort was to issue a
long-term plan and an environmental impact statement (EIS) by
December 1991. In a May 1992 Memorandum of Understanding, the Forest
Service and APHIS joined this effort. However, as negotiations have
continued on ways to better manage brucellosis in bison, many
deadlines for completing this effort have come and gone. In the
interim, Montana filed a complaint in January 1995 in federal
district court contending that the conflicting policies of APHIS and
the Park Service threaten Montana's brucellosis-free certification.
To settle the lawsuit, Montana, the park, and APHIS agreed to develop
interim bison management procedures to prevent the potential spread
of brucellosis from bison to domestic cattle. The August 1996
interim plan was implemented over the last winter and remains in
effect. Where cattle graze in Montana, the interim plan has no
tolerance for bison. As a result, about 1,100 bison were shot or
captured and slaughtered last winter. The procedures do allow bison
to use adjacent federal lands where cattle either do not graze or are
not present when bison are in the area. Early this year, to move
forward on the long-term plan, the Park Service committed staff from
its field area office to assist in preparing both documents. The
park and the state are committed to issuing a draft management plan
and an EIS for public comment in July 1997 and to completing final
products by March 1998. In June 1997, the state, APHIS, the Forest
Service, and the Park Service agreed upon a preferred alternative for
managing brucellosis and Yellowstone's bison population. Generally,
the alternative provides for the capture and shipment to quarantine
of animals testing negative for brucellosis. These animals would
then be made available to Native American tribes to help establish
herds. The alternative also provides for the capture of bison to
control their movement onto private lands; the hunting of bison in
certain situations; the vaccination of bison when a vaccine is
developed for them; and the acquisition of additional winter range
outside the park when such range becomes available for purchase from
willing sellers.
Three separate ongoing cooperative efforts are addressing brucellosis
issues in the area south of Yellowstone Park. First, Wyoming has
been working with APHIS, the Park Service, the Fish and Wildlife
Service, and the Forest Service since December 1995 to develop an
interim brucellosis plan for elk and bison. The goal is to design a
plan that will maintain the state's brucellosis-free classification,
reduce damage to private property, and sustain the free-roaming bison
and elk herds. Last November, the agencies received public comments
on a draft plan, which they are now analyzing.
A second effort is being conducted by Grand Teton National Park and
the National Elk Refuge, in cooperation with the Wyoming Game and
Fish Department and Bridger-Teton National Forest, to develop a
long-term management plan for the Jackson bison herd. The plan's
goal, in part, is to minimize the potential for transmitting
brucellosis among bison, elk, and domestic livestock. A draft plan
and environmental assessment were published in September 1996, public
comments were received, and a final plan is expected in August 1997.
To reduce the risk of transmission among bison, elk and cattle, the
draft plan proposes measures such as baiting or feeding the bison for
a limited time to keep them from migrating onto the National Elk
Refuge, separating bison from elk and cattle when the potential for
transmission is greatest, vaccinating cattle, using a vaccine on
bison when one is developed for them, and developing disease
transmission risk assessments to use as the basis for wildlife
management programs. The plan would also allow small public bison
hunts outside the park and make some bison available to Native
Americans.
A third effort, led by the Wyoming Game and Fish Department, is to
develop brucellosis management action plans for each of the state elk
herds and the surrounding range used by cattle. The objective is to
develop plans that minimize the potential for transmitting
brucellosis among elk, and from elk to cattle, by reducing the
animals' overlapping use of rangeland and conducting other actions
designed to ultimately eliminate the disease.
Finally, at the request of the Secretary of the Interior late last
winter, the National Academy of Sciences' Commission on Life Sciences
agreed to review the scientific data on brucellosis contained in
published studies in the fields of wildlife ecology, epidemiology,
zoonotic diseases,\5 infectious disease control, animal physiology
and health, and veterinary science. The review is to examine the
scientific issues surrounding the transmission of brucellosis among
wild and domestic animals, especially among bison and cattle;
determine the extent of infection in wild herds; and identify the
additional research that is needed on these subjects. Specific
questions include, among others, the relationship between blood tests
and the ability of animals to transmit the disease, the effectiveness
and safety of vaccines, and the impact of various risk reduction
measures. The study is due to be published by October 1997.
--------------------
\5 These are animal diseases that can be communicated to humans.
OBSERVATIONS
---------------------------------------------------------- Chapter 0:5
The impact of Yellowstone's bison and elk herds on the park's range
and riparian areas and the potential for these animals to transmit
brucellosis to cattle are highly controversial, sensitive, and
emotional issues for the affected parties. Scientific and historic
data on some aspects of these issues are limited, and when agreement
does exist, the data are often interpreted differently, reflecting
differences in people's values and in agencies' mandates and
missions. Many questions will need to be answered before these
concerns can finally be resolved. For example, how will the
reintroduction of the wolf in Yellowstone affect the size of the elk
herd and, subsequently, the park's woody vegetation?
This past winter, the slaughter of bison that migrated out of the
park, combined with the winter kill, reduced the bison herd to about
half of its size the previous year. In the short term, this
reduction may limit the migration of bison from the park, relieve
some of the immediate pressure on the Park Service to take management
actions, and create an opportunity for the Park Service and its
critics to complete and assess the results of studies such as the
National Academy of Sciences' review of brucellosis issues. The
results of these studies are needed to make informed management
decisions.
-------------------------------------------------------- Chapter 0:5.1
This concludes my statement, Mr. Chairman. I would be happy to
respond to any questions you or other Members of the Subcommittee may
have.
WINTER RANGES AND MIGRATION ROUTES
OF THE GREATER YELLOWSTONE AREA'S
ELK HERDS
=========================================================== Appendix I
(See figure in printed
edition.)
Source: Yellowstone Center for
Resources, Yellowstone National
Park, National Park Service.
(See figure in printed
edition.)
WINTER RANGES AND MIGRATION ROUTES
OF THE GREATER YELLOWSTONE AREA'S
BISON HERDS
========================================================== Appendix II
(See figure in printed
edition.)
Source: Spatial Analysis
Center, Yellowstone National
Park, National Park Service.
(See figure in printed
edition.)
*** End of document. ***