A federal agency recently collected semen samples from 39 bison bulls outside Yellowstone National Park, the beginning of a two-year study intended to measure the risk of venereal transmission of brucellosis between wild bison and domestic cattle. Researchers call the fieldwork a success, but the Buffalo Field Campaign (BFC), an organization that works to protect wild bison, condemns the study as abusive.
"It's pretty invasive and extremely unnecessary," says BFC's Stephany Seay.
The U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) in April began darting and drugging bison bulls on Gallatin National Forest land outside Yellowstone's boundary, and then probing their anuses to induce ejaculation. Researchers then painted the animals with a blue stripe to prevent repeat sampling.
"We use what's called an electro-ejaculator," explains Ryan Clarke, APHIS's epidemiologist in the greater Yellowstone area. "There's a probe that's inserted into their anus and sits over their sexual glands—the prostate and the bulbourethral gland—and it sends a small current through those glands to simulate coitus. When that's passed through those glands, they get excited, and the animal ejaculates into a container."
The samples, Clarke says, are sent to APHIS's lab in Ames, Iowa, to be tested for Brucella abortus, the causative agent of bovine brucellosis, a bacterial infection that causes cattle, elk and bison to abort their young.
Both BFC and APHIS suspect the study will ultimately show that bison pose a negligible risk of sexually transmitting brucellosis—which is why Seay calls the study unwarranted.
"It's something that's already widely accepted as an immeasurable risk," she says, "so we feel the study is completely senseless."
Still, the invasive anal probing, researchers say, may prove to be an act of love.
"I think at the end of this study there's a very real possibility that we'll reinforce the idea that bull bison have negligible risk as far as transmitting brucellosis," Clarke says. "And if that is in fact true, then I think it opens up the discussion for more bull bison tolerance."