Birth Control Darts Fired at Idaho Wild Horses to Manage Herd Growth

Federal wild horse specialists from Idaho and Oregon have been trained in how to shoot birth control darts into the rumps of wild horses. This technique could soon see wider use to slow the growth of wild mustang herds. The federal government estimates more than 40,000 wild horses roam the Western range.

Field staff from the Bureau of Land Management in Challis, Idaho, and Ochoco National Forest in central Oregon traveled to the non-profitScienceand Conservation Center in Montana to learn about a wildlife contraceptive calledPZP. Center director Jay Kirkpatrick said the birth control can be injected in wild horses via a small dart fired from an air gun.

This summer, theBLM's Challis Field Office injected five wild mares in the initial deployment of the field darting technology in the Northwest.

Lloyd noted that some of Idaho's wild horses avoid people, making it "problematic" to get close enough to use a dart gun. Mares need to be re-injected annually for maximum effectiveness.

Kirkpatrick said wary animals can be brought within darting distance with bait or water traps.

Another logistical challenge with darting is keeping track of which wild mares have been treated and then finding them again to deliver an annual booster in subsequent years. Kirkpatrick explained range managers often recognize individual wild horses on sight. Photo identification has also proved viable in herds with variation in coat colors and patterns. If a horse has been previously caught in a roundup, it may have a visible brand.

Kirkpatrick said he has worked on thePZPcontraceptive for decades. His center produces the doses used byBLM, five tribal wildlife departments, and some private wild horse preserves. He calledPZPvery safe for animals and the environment.

PZPis a pig-derived protein that stimulates antibodies when injected, which interfere with fertilization. Wild horse herds reproduce at rates of up to 20 percent per year. Lloyd saidfertility controldarting would be more attractive to range managers like himself if the drug lasted longer, on the order of five years even.

Although the Ochoco National Forest sent three wild horse specialists to train on the technology this year, a spokesman said those Forest Service workers have no plans at the moment to fire any birth control darts into rumps.

The Ochoco herd probably descended from horses which escaped or were purposely freed by pioneer miners and ranchers. The same is true for central Idaho's wild horses according to an environmental assessment prepared by theBLM. The horses have few natural predators and get blamed for resource damage by other forest and range users.

Originally Posted By NWPR