The management of wild horse herds and flourishing urban deer populations is so politically charged that science often gets pushed aside, said Jay Kirkpatrick, of the Billings-based Science and Conservation Center.
Kirkpatrick, one of the founders of SCS, spoke to the Conservation Roundtable on Tuesday at the First Interstate Operations Center. His company, a nonprofit, creates a vaccine called PZP that acts as a contraceptive in wild animals.
Burgeoning wild horse populations on Western federal lands — including the Pryor Mountain and McCullough Peaks wild horse ranges — have led to controversial roundups and trapping of the horses to keep herds from growing unchecked.
Urban deer, finding safe havens in city parks and wooded areas, likewise have grown and required some cities to find ways to reduce their numbers. In Helena, deer are trapped and killed. In Glendive, Colstrip and Fort Benton, the deer can be hunted under special programs.
Kirkpatrick argued that these methods don’t address the underlying problem — reproduction. He said that removal of animals simply results in compensatory reproduction, which can lead to increased birth rates among the targeted animals.
PZP is a vaccine made from pig ovaries that, when injected into a female animal, causes her antibodies to attack. The antibodies also seek out the animal's own eggs and prevent conception. Like any vaccine, the effects wear off and a booster is needed.
SCS proved the possibilities of the immunocontraceptive at Assateague Island National Seashore on the East Coast. In the Maryland portion of the park, PZP has kept the wild horse herd at a sustainable level without roundups or removals.
“We stopped growth overnight and it took several years to start to decline,” Kirkpatrick said.
The cost, he said, is roughly $106 to dart one horse. In the Pryor Mountains, he estimated the cost to remove one horse at $2,165.
At Fire Island National Seashore in New York, Kirkpatrick said his company had similar results inoculating deer. The white-tailed deer population on the island had grown from only 50 in 1974 to 500 to 700 by 2003. Through the inoculation program, there was a 70 percent reduction in the number of deer.
“There are only two kinds of people on that island,” Kirkpatrick said, “deer haters and deer lovers, and they’re both happy.”
According to the Fire Island website, though, “Because of complex issues related to the use of PZP or other immunocontraceptive vaccines for research, plans for a continued or new research project in 2010/11 were not able to be conducted on Fire Island.”
PZP had similar results on a herd of bison that roam Catalina Island off the coast of California. In one year, births fell from 29 to three. The hope is to keep the herd at a manageable level.
Opponents say that choosing which mothers get to give birth is unnatural and can affect the herd’s genetics and social dynamics. Kirkpatrick said deer contraception has been fought by several state fish and game agencies that think that hunting is the best way to remove excess animals. Unfounded rumors have also circulated that eating a deer that had been injected with PZP would cause breast enlargement in men and sterility in women. Legislatures and politicians have attacked the process, too, Kirkpatrick said.
“All of what I’ve told you has been rolled in together to create a socially constructed ignorance,” he said.
The real issue, he said, is who gets to use and benefit from public lands.