Office of the Secretary

Contact: Mike Gauldin 202/208-6416

For Immediate Release: March 14, 1997

Harsh winter, shooting by Montana state riflemen claim almost two-thirds of nation’s last wild bison herd

Nearly half of the bison herd that roamed Yellowstone National Park have died so far as a result of the twin onslaughts of a harsh winter and the state of Montana’s controversial policy of shooting bison which venture out of the park searching for food.

The Yellowstone Herd included an estimated 3200-3500 animals at the beginning of the winter season, but this week only an estimated 1300-1500 surviving bison could be accounted for based on an aerial survey earlier this week of the park and adjacent National Forest land. So far this winter 1,059 bison, about a third of the original herd, has been sent to slaughterhouses or shot by Montana state riflemen.

Montana has reported killing about 100 bison on public and private land since February 26, when Interior Secretary Bruce Babbitt sent the Governor of Montana a letter urging him to stop the killing and work together to identify immediate solutions aimed at saving the bison.

“This needless and unnecessary shooting of Yellowstone bison must stop now,” said Babbitt. “The continued killing of bison by the State of Montana is threatening the future of America’s free roaming wild herd.”

The bison at Yellowstone is the last remnant of the free-roaming wild herd of the American west, a national symbol of the nation’s commitment to conservation. The unusually severe winter has driven a number of bison outside the boundary of Yellowstone in search of food. When bison roam outside of the park area, they are ordered shot by the State of Montana.

“The unacceptable killing of bison must stop. Between the ice and snow and what’s left of the harsh winter weather yet to come, and the continued killing by Montana, there is cause for serious concerns of just how many bison will survive,” said Babbitt.

To date there are no documented findings or cases of cattle contracting brucellosis from bison in the wild. Although elk and bison both can carry brucellosis, Montana allows elk to roam free.

-DOI-

The NAS, an independent advisor to the government, will determine:

I. What are the factors that determine the risk of transmission of the bacteria Brucella abortus to cattle from bison in Yellowstone National Park and Grand Teton National Park?

• What is the state of scientific understanding for the transmission of Brucella between wildlife species and between wildlife and cattle?

• Does Brucella affect the reproductive potential in bison generally, and specifically bison in the Greater Yellowstone Area?

• Does Brucella pose a risk of transmission when it occurs in bison but is not present in the reproductive system? What risk is associated with infected males? (Is it dynamic?)

• What is the relationship among serology, culture test results, and likelihood of infectiousness? Can serology results be used as a reliable predictor of infectiousness?

• What is the true prevalence of Brucella abortus in GYA bison and elk? What information is available regarding the prevalence of Brucella in other mammals in the GYA?

• What is the risk of direct or indirect (via aborted fetus, placenta, body fluids deposited on the ground, etc.) transmission of Brucella abortus from bison to cattle, from elk to cattle, and from elk to bison or vice versa? What is known about the prevalence of Brucella in GYA wildlife other than bison or elk and risk of transmission to cattle?

• In the event that Brucella is removed from bison but not simultaneously from elk, what is the risk that elk will serve as a reinfection pathway for bison?

• What is the known risk of Brucella transmission compared with other disease?

• What is the state of scientific understanding of the safety and effectiveness of exiting vaccines to control brucellosis? Why are these vaccines less effective in bison than in cattle?

• If a vaccination program specific to bison were undertaken, would the outcome have a high likelihood of success given the presence of Brucella in elk and other wildlife?

II. Based solely on scientific considerations, what is known about the relative risk reduction potentials of the various optional approaches to reducing the risk of transmission of Brucella from wildlife to cattle? Such approaches include:

•Vaccinating bison

•Vaccinating cattle

•Separating cattle and bison during the bison abortion season or through the entire birthing season

•Limiting cattle on the proximity of the park borders to steers only

III. What is the role of vaccine development for bison and elk? Can Brucella be eliminated totally from the GYA by development and use of a vaccine? What would be the theoretical tradeoffs between a vaccine-only approach and a vaccination approach combined with a test and slaughter program?

[Interior Secretary Bruce Babbitt has requested the National Academy of Sciences complete its study by Oct. 1, 1997]

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Scientific Background

Bison Fundamentals: More than 30 million wild and freeranging bison (Bison bison) once roamed the West. Yet by 1902 only a remnant population of 23 wild bison remained in Yellowstone National Park. That year, bison were translocated from domesticated herds in Montana and Texas to Yellowstone. These and the remaining animals formed the foundation for the current wild bison population found in the United States.

Yellowstone National Park is a harsh winter environment for bison. Cold is not a major concern because bison thermoregulate. In addition, hot springs and other thermal features aid their survival. However, one of the most significant challenges for bison in Yellowstone is deep snow. Bison have saved their energy by using plowed roads and compacted snowmobile trails that facilitate their travels especially to winter range. These energy savings and easier access to winter range, over the past seventeen years, are factors contributing to bison population increases.

The 19961997 winter in Yellowstone National Park has delivered dense, compacted, rockhard snow that has made the traditional bison feeding areas unavailable. This situation has set the stage for natural population adjustments. The 1996 summer bison herd of roughly 3500, approximately a quarter occupying the northern range, were confronted with the winter of 1997.

Wild, free ranging bison do not recognize political boundaries. In search of scarce food resources in the19961997 winter, bison move along the energy efficient snowmobile trails and groomed roads that lead the bison to their traditional winter range found at lower elevations. To date, more than 1,000 bison have been shot or sent to slaughter during the winter of 1997. Additional animals have died due to the harsh winter weather and other natural processes. Based on recent aerial surveys, the bison population is currently about 1,300.

Brucellosis Fundamentals: Brucellosis is a contagious bacterial disease caused by various species of the bacteria Brucella which infects domestic animals, wildlife, and humans worldwide. In North America the primary livestock hosts of Brucella are cattle, goats, swine, and sheep. The principal North American wildlife hosts are bison, elk, caribou, reindeer, and feral and exotic swine. Brucellosis may also occur in carnivores, including members of the dog family.

Brucellosis in Yellowstone National Park bison was first reported in 1917 and an endemic infection has persisted since that time. Approximately 45 percent of the current bison herd tests seropositive for the antibody to Brucella. However, not all seropositive animals are currently infected with the bacterium. The original source of infection is unknown; however, Brucella abortus was introduced to North America with imported cattle. Therefore, the bacteria probably was transmitted from domestic livestock to bison. Many elk residing in the Greater Yellowstone Area also test serologically positive for brucellosis. The percentage of animals testing positive varies from location to location within the Greater Yellowstone Area and may be related in part to the concentration of animals on winter feed grounds.

Brucellosis is typically transmitted through ingestion. The Brucella bacteria are transmitted in aborted tissues, reproductive tissues and discharges, especially just prior to, during, or soon after abortion or live birth. The bacterium may also be shed in milk for variable lengths of time. Although transmission has been shown to occur between and among cattle, bison, and elk under experimental conditions, the risk of transmission of brucellosis between bison and cattle in the wild has not been determined. There is disagreement over the primary means of brucellosis transmission among bison and current data are insufficient to resolve this issue.

Brucellosis in cattle is characterized by abortion, infertility, reduced milk production, and other reproductive problems. Although on occasion abortion may occur in wild bison herds, brucellosis does not prevent the growth of the Yellowstone bison herd.

In humans, brucellosis was formerly known as undulant fever, a disease that is rarely fatal. Livestock and slaughter industry workers, veterinarians, and consumers of unpasteurized milk and products made from it have the highest risk of contracting the disease. If properly cooked, meat from infected animals is not a health risk. There have been two documented transmissions of brucellosis to humans from elk in Montana. The transmission arose from individuals handling elk fetuses and membranes.

There is no effective treatment or cure for animals infected with Brucella. However, a preventative brucellosis vaccine (Strain 19) has been developed for use in cattle. Its primary use is to increase herd immunity. On average it is 65 to 70 percent effective in cattle. The effectiveness of Strain 19 on captive bison is less than that for cattle. Two other vaccines, B. Neotomae and strain RB51, are currently under study. Strain RB51 has been licensed for use in cattle calves only. Initial trials of RB51 in captive, pregnant bison caused some bison to abort when given a dose via an inoculation route that had been proven safe in pregnant cattle. However, additional tests of the safety and effectiveness of RB51 on bison are underway. Methods for brucellosis prevention in wildlife including bison, using techniques currently employed on cattle have not proven to be effective. Currently, domestic cattle can beeffectively inoculated against brucellosisbison can not.

Knowledge Required: Combating brucellosis in wildlife populations such as the bison of Yellowstone National Park requires policies that are built upon a solid foundation of science. The National Academy of Sciences has agreed to undertake an independent study of the scientific issues associated with the brucellosis problem. Key elements of the study will address:

o The transmission of Brucella among cattle, bison, elk, and other wildlife species;

o The relationship, if any, between the bison population dynamics and brucellosis;

o The ability of serology testing to estimate true infectiousness;

o The efficacy and safety of existing vaccines for target and nontarget species and the need for new (including bisonspecific) vaccines;

o The nature, and likely success or limitations, of a wild animal vaccination program; and

o Optimal approaches to reducing the risk of transmission to cattle and among wildlife.

Secretary Bruce Babbitt has requested The National Academy of Sciences complete its study by October 1, 1997.

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• The Yellowstone bison herd is the largest freeroaming bison herd and a national symbol of the nation’s commitment to conservation. The National Park Service brought the last 23 wild bison back from the brink of extinction to return them to their place in the ecosystem of Yellowstone.

• The NPS estimates that about 1300 bison remain in Yellowstone National Park and adjacent National Forest land. Instead of an “overpopulation” of bison, at this point the NPS is concerned that the bison population may drop to critical levels if continued shooting adds to the expected winter mortality.

• An unusually harsh winter has forced bison out of the sanctuary of Yellowstone National Park and on to surrounding lands that historically served as their winter range. Snowpack in the park is 200% above normal. National Forest lands around the park, where bison are being shot, were established in part to protect winter range for the wildlife of the park.

• 1059 bison have been killed so far to protect cattle from an undefined risk of infection that might be present if cattle were to come into close contact with bison. There is currently no imminent threat of cattle coming in contact with bison. Under the Interim Bison Management Plan, Montana has slaughtered 504 bison (including 464 captured by the National Park Service). Montana has shot 548 bison. NPS has destroyed 7 bison due to injuries sustained during capture or shooting operations.

• Since January 30, the National Park Service, with USDA’s Forest Service and the Animal and Plant Health Inspection Service (APHIS), has asked Montana to stopthe killing of bison around Yellowstone National Park on National Forest lands, and to minimize Montana’s killing of bison on private land around the Park. NPS, APHIS and Forest Service asked Montana to allow bison to roam free on National Forest lands because bison need to disperse over a wider area while their winter range in the Park is largely covered with ice and snow.

• Though elk and bison both carry brucellosis, Montana allows elk to roam free, and supports public hunting on public lands to control their numbers. Wyoming supports public hunting of bison on National Forest land adjacent to Yellowstone.

• Although transmission of brucellosis has been shown to occur between and among cattle, bison, and elk under experimental conditions, the risk of transmission between bison and cattle in the wild has not been determined.

• Montana has shot over 135 bison on public lands in the West Yellowstone area since January 30, when APHIS informed Montana that such shooting was not necessary to protect the State’s brucellosisfree cattle rating. Montana is not caught between conflicting federal agencies; USDA and DOI are committed to reasonable contingency proposals and longterm solutions.

• Contrary to Montana’s public statements that they are being “selective” in their shooting of bison in the West Yellowstone area, Montana has shot bulls and calves without knowing whether they were diseasefree or not.

• If APHIS and NPS contingency proposals are not adopted by Montana, the Interim Plan would allow Montana to continue shooting most, if not all, bison in the West Yellowstone area of the Gallatin National Forest.

• The National Park Service has not removed bison, by shooting or slaughter, since February 13, 1997. Because NPS is doing all it can to protect the remaining bison herd, NPS will only shoot bison for humanitarian reasons (i.e., injury) or to protect against imminent harm to life or property.

• There are no cattle in the West Yellowstone area and cattle will not be returned to the area before summer. Any potential conflicts with cattle can be resolved by ensuring that cattle are managed to provide a sufficient time interval after the return of bison to the Park to avoid a significant risk of contact between bison and domestic cattle.

• There is no safe and effective vaccine for brucellosis in bison. Use of cattle vaccines in bison causes bison to abort their calves.

• Management of the freeroaming bison and the 2.2 million acres of Yellowstone National Park cannot be validly compared to other parks. Wind Cave (28,295 acres) and Theodore Roosevelt (69,701 acres) manage their bisonpopulations within specific ranges established for each park. The Wind Cave population range is 300400 animals and Theodore Roosevelt's range is 300750 animals. These parks do not mange their bison as free ranging bison in part because the parks have been fenced and are surrounded by private land.

• The conflict with bison is one aspect of the development and use pressures near or up to the park boundaries that Yellowstone National Park has never before experienced.

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