and 1990s, the agency managed to find places for most of the horses it removed, but then this never-ending cycle began to create a crisis. As the economy faltered in the first decade of the 2000s and drought caused the price of hay to rise, there wasn’t as much demand for horses. Between 2002 and 2012, the number of horses adopted each year fell by two thirds, from almost 6,000 to about 2,000, but the agency continued to gather between 5,000 and 10,000 horses a year. BLM holding facilities filled with horses no one wanted—animals who would never be returned to the wild and would cost $45,000 each to care for over a 30-year life span (versus $1,000 at most to gather, treat and release a mare with PZP-22, preventing two births over two years). By 2013 there were 47,000 horses in BLM holding areas—more than the estimated 40,000 animals still in the wild. The agency was spending about half its wild horse budget to care for them. And Congress was refusing to provide more money to set up new holding facilities.
Meanwhile, the outlook for the land and the horses left on the range was not good. In places with rainfall amounts as low as Cedars’, high numbers can put animals at risk during dry years—and with climate change, there are more and more of those. In other places, the land, much of it semi-desert, suffers. Horses eat the higher-nutrient native grasses and lower quality invasive species can take root in their place. To a visitor, it may look as though there’s enough vegetation on the land. But horses don’t eat juniper or sagebrush or greasewood.
Guy Palmer, a Washington State University professor, explains it in a video for the National Academy of Sciences. “If the horses just continue to grow ... in the end, two things are assured to happen—the rangeland loses its quality; it’s actually destroyed,” says Palmer, who chaired a National Academy of Sciences committee that urged the BLM to adopt PZP. “[And] eventually the horses themselves will become ill.”
The strategy of roundup and removal has brought the BLM to a dead end, says Boyles Griffin. “It’s simple arithmetic; it’s not sustainable,” she says. “We have a solution: You have to gather only as many as you can adopt, and then you have to contracept like crazy.” Such an approach, she argues, pointing to a report in the Journal of Zoo and Wildlife Medicine, could potentially save taxpayers tens of millions over a decade.
As fewer people adopt horses, the BLM has been forced to slow the pace of roundups. And soon-to-be-published HSUS research may help persuade the agency to start relying more on PZP-22. The vaccine, designed to be administered every other year, is being used on a trial basis at two BLM herd management areas, Sand Wash Basin in Colorado and Cedar Mountains in Utah. (Click here for a map.) At Cedar Mountains, where 600 horses now roam an area the BLM believes can support 200 to 400, PZP-22 held foaling rates below 5 percent in 2013, and preliminary data shows it is expected to significantly reduce reproduction this year from the 60 percent observed in untreated mares. (Results from Sand Wash won’t be available until 2015.)
The Cedars data bolsters a 2013 recommendation by the National Academy of Sciences that the agency start using contraception immediately, beginning with the best option available—PZP. The Cedars results, due to be published in 2015, form the strongest argument so far that the BLM should be using contraception in the majority of its herd management areas, expanding from the seven BLM sites where PZP or PZP-22 is currently employed.
“Cedars is the big one”—the evidence wild horse managers have been waiting to see, says Allen Rutberg, a Tufts University professor and PZP researcher working with The HSUS on the trials.
Joan Guilfoyle, chief of the BLM’s wild horse and burro division, won’t commit to vastly increasing use of PZP but says the agency is looking for a way to follow the NAS recommendations and provide proven contraceptives to all its horse management areas. “PZP and PZP-22 are so far the most effective tools we have. We know they 