The iconic image of the western cowboy riding through the range and rounding up wild horses with nothing but his lasso and trusty steed is a far cry from how the 21st century Bureau of Land Management rounds up the horses on its land in the Intermountain West. Today, the BLM cowboys are helicopter pilots herding animals into a holding area.
“It’s kind of like a bee that hovers over the animals and herds them in to a trap,” said Tom Gorey, a spokesperson for the Bureau of Land Management. “And it’s really the most way humane and efficient way.”
But after the helicopter gathers the horses, the animals either have to be adopted or sent to a long-term range in the Midwest—the BLM doesn’t destroy the animals—and this process can be expensive, up to 60 percent of the Wild Horse and Burro Program’s $63.9 million budget for fiscal year 2010, Gorey said.
With the estimated 38,400 wild horses reproducing faster than the BLM can remove them, the BLM is looking to quadruple the use of another option it’s been using since 2004: the fertility control drug PZP.
A horse sperm has proteins that fit protein receptors on a horse egg. PZP is made up of sperm proteins, but from a pig. Once the vaccine is injected into a horse the horse’s body will create antibodies, which will attack the pig protein, said Jay Kirkpatrick, director of the Science and Conservation Center at ZooMontana in Billings, Montana. Those same antibodies will attach to the sperm receptors on the horse egg and cause them to change so they can no longer receive the proteins from the horse sperm. The Science and Conservation center is one of the largest producers and distributors of the PZP vaccine.
After the mares are injected with the $24 PZP pellet they become infertile for 22 months, but in order to apply the fertility drug, the horses still have to be corralled by a helicopter.
“PZP is effective up to a point,” Gorey said. “But the big problem for us is the horses are scattered across 30 million acres and it’s a hard job herding horses and applying it and releasing them.”
Use of the drug may reduce the frequency of gathering horses, “in theory,” said Gorey.
“Ordinarily we gather every four years, if [PZP] were working it might allow us to stretch the amount of time between gathers.”
Since the inception of the program, the BLM has been treating about 500 horses per year with PZP and they’re currently looking to expand the program to include 2,000 animals a year. But for the program to go further, the BLM must wait for recommendations from the National Academy of Science, which aren’t expected to be complete until 2013, Gorey said.
Addressing the reproductive problem is the only real answer to the wild horse population issue, Kirkpatrick said.
“The problem is reproduction, you can remove horses until the cows come home,” Kirkpatrick said. “But they’re reproducing and you’re going to do this forever.”
Until the fertility control program can be perfected, the BLM will still have to rely on its current gather system.
“The more we can rely on fertility control the better because more horses can stay on the range,” Gorey said. “But there are challenges associated with applying the drug.” The BLM’s optimal wild horse population is 26,600, making the current level 12,000 animals over. “For the immediate future gathers will be necessary,” Gorey said.