Beyaz for Bison

Humans have attempted to control or eradicate different wildlife diseases for many years. Currently, scientists are researching the potential use of contraceptives to control populations, and in turn, control diseases within and between populations. The focus of concern is not only that wildlife spread disease between them, but also that the diseases can be transmitted to humans and livestock. This is a fairly new research project, with modern history of the practice beginning in 1971. However, it was used thousands of years ago by North Africans when they inserted stones into camel’s uteri in order to sterilize them.

Ideally, the goal is to “downsize natural ecology to fit the geography of modern niches without altering the behavior of animals or the balance between species” (1). The contraceptive use should not have any side effects on the wildlife.

The idea for modern wildlife contraceptive came from a wildlife biologist in Billings, Montana named Ron Hall. He understood that under the newly passed Wild Free-Roaming Horse and Burro Act outlawing killing of the creatures, they would soon become exponential in population size. Hall proposed the issue to biologist Jay Kirkpatrick of Montana State University, who immediately worked on the study and project with his students. The hand delivery of sterilizations to wild horses was not warmly welcomed in the public eye, causing Kirkpatrick many issues at first, but eventually was accepted when the rise in populations started effecting cattle numbers. Eventually, Kirkpatrick was able to alter a failed human contraceptive to create antibodies that worked against the horses’ immune systems, creating barriers to block sperm from eggs. Scientists are now working on oral contraceptives to leave as bait, instead of having to dart the animals.

Labs in Australia, however, are working on a slightly different approach: the use of viruses to sterilize animals. A recent discovery found that recombinant versions of cytomegalovirus and myxoma virus sterilize an animal if exposed to them. New Zealand is also developing genetically modified nematodes that are efficient in sterilizing invasive possums.

Now that smaller populations of species are becoming more abundant, it is opening up resources for each member of the population. A scientist recently pointed out the availability of water for wildlife with the use of contraceptives: “Where you would normally get losses of young calves in very dry seasons, you can now move from one water hole to the next one.”


With smaller populations comes less chance of disease spread. In 2013, the Department of Agriculture published research on the use of contraception in bison populations in order to prevent Brucella abortus (a zoonotic disease that causes abortions in female bovines) from wiping out herds. Their eventual findings were that the developed vaccine “could provide a potential nonlethal management tool to prevent transmission of the disease in an infected bison population”(2).

-Jenna Rindy




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