Congress takes aim at bison ... and locks out endangered species.

A proposal now before Congress would require sterilizing or killing thousands of bison in Yellowstone National Park to keep them from infecting local cattle with Brucella bacteria.

Infection with Brucella causes an animal to abort one or more of her fetuses and lowers milk production. Since the late 1950s, the number of infected cattle herds in the United States has dropped from 127,000 to 53. Cattle from states that have infected herds must be tested before crossing state lines. Cattle in Wyoming, Montana, and Idaho are free of the bacterium, but some ranchers say that bison in neighboring Yellowstone threaten their animals' health. Animals pick up Brucella when they investigate a fetus aborted because of the disease and ingest bacteria in the tissue, placenta, or blood. Scientists first detected Brucella in bison in the early 1900s. Today, roughly half of the bison in Yellowstone carry the bacterium, according to some estimates. However, the number of bison that are infectious or have lost their fetuses because of the bacterium remains unclear, says Jack Rhyan of USDA's National Veterinary Services Laboratories in Ames, Iowa. His lab is currently doing studies to provide more definitive data.

On March 7, a Senate subcommittee held hearings on legislation that calls for slaughtering or sterilizing all bison in Yellowstone that test positive for Brucella or that can't be tested. Some scientists fear that the proposed action would result in the death of noninfectious animals that have the antibodies and therefore test positive.

The bill, introduced by Conrad Burns (R-Mont.) in May 1995, would require National Park Service staff to test the blood of the park's roughly 4,200 bison for antibodies to Brucella. The staff would have to vaccinate and quarantine for 1 to 3 months each bison that tests negative. Those that test negative but can't be quarantined would have to be sterilized or slaughtered. The animals killed under the program would go to "Indian tribes and other suitable recipients" for eating, the bill states. People can catch brucellosis from handling raw meat but not from cooked meat.

Scientists disagree on how much risk-if any-infected bison pose to cattle, says Elizabeth S. Williams, a veterinarian at the University of Wyoming in Laramie. However, she considers the risk small. Cattle rarely come into contact with an aborted bison fetus, she says.

"There has never been a single documented case of free-ranging bison transmitting [Brucella] to cattle," Robert M. Ferris asserts in written testimony submitted to the subcommittee. Ferris works for the Defenders of Wildlife, a conservation organization in Washington, D.C.

The legislation would prove very costly, Ferris argues, and ignores the ongoing efforts of private, state, and federal groups to control the disease in and near Yellowstone.

Alternatives to killing or sterilizing the animals include improving efforts to immunize cattle and to separate them from bison, notes Williams. A brucellosis vaccine for cattle exists, and researchers are developing one for bison.

. . . and locks out endangered species

On March 13, Congress voted to continue the 11-month-old ban that prevents the Fish and Wildlife Service from listing additional species as endangered or threatened (SN: 7/15/95, p. 43). If allowed, the service would have added 240 plants and animals to the list, a spokesperson says.