Birth control effort aims to maintain McCullough herd

Posted 8/6/13

The horse will remain healthier to boot, thanks to the contraception, according to researchers Ada Inbody and Patricia Hatle.

Inbody belongs to Friends Of A Legacy, a group that supports the wild horses in the peaks. Hatle, a range/wild horse …

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Birth control effort aims to maintain McCullough herd


A McCullough Peaks mustang mare named Dazzle may have dodged the dart Thursday, but very soon she will be inoculated to preempt pregnancy for another year.

The horse will remain healthier to boot, thanks to the contraception, according to researchers Ada Inbody and Patricia Hatle.

Inbody belongs to Friends Of A Legacy, a group that supports the wild horses in the peaks. Hatle, a range/wild horse specialist with the U.S. Bureau of Land Management, is tasked with looking after the animals. The bureau manages all wild horses and burros.

In a shallow draw, Dazzle grazed in bliss with the members of her band.

The sagebrush is short and dusty and the grass stunted. A little precipitation would be nice, but it is an iconic Wyoming image, just the same, of untamed beauty. Although not plump, Dazzle and her equine companions look healthy.

“It’s just amazing how good they look,” Inbody said.

A peaks mustang was grand champion gelding at the Park County Fair this year, Hatle said with a hint of pride.

Inbody holds a dart gun containing porcine zona pellucida or PZP, a form of birth control that has been used on horses for the last 20 years.

In 2004 McCullough mares were treated with PZP. In 2009, during what the bureau calls a gather, 92 adult horses were removed and 24 mares were treated with PZP.

This year, five foals were born so far. There were 46 foals in 2009, with 24 in 2010, 27 in 2011 and 14 in 2012, Hatle said.

Sixty to 70 mares have received the airborne inoculation for the last three years. This year, 65 mares are on the booster shot list, Hatle said.

“I’d rather see them do birth control than a roundup,” said Ken Martin, who operates Red Canyon Wild Mustang Tours.

The herd has 140 adults this year. The bureau says the appropriate management level is 70 to 140 adults for the McCulloughs.

However, studies say the population shouldn’t drop below 100 adults to maintain good genetics in this herd, Hatle said.

Gathers will not be needed if the bureau can control the number of pregnancies. The bureau could use low-impact bait traps to catch five to 10 horses from time to time when needed to control the population.

On the flip side, if foal recruitment is low, mares can again become pregnant when the PZP wears off in one year, Hatle said.

Gathers often are controversial events, as helicopters can be used to drive the horses to a nearby location where they can be sorted and culled. The extracted mustangs are put up for “adoption.”

“Wild horses and burros have virtually no natural predators, and their herd sizes can double about every four years,” said the bureau.

As of July, there were 47,723 wild horses across the West being fed and cared for at BLM short-term corrals and long-term pastures, according to bureau figures.

There are no worries if a PZP arrow hits the wrong target. The drug has no effect on studs or humans. Nor does it harm a fetus if a pregnant equine is treated, Hatle said.

The women gave a demonstration. A square of carpet with black spots was propped up 18 yards away.

While Hatle spotted with binoculars, Inbody swiftly aimed and fired the rifle. With a pop sounding like one from a .22 short round, the dart left the barrel to hit the target dead center with a thump like a wrangler slapping a horse’s rump.

The dart’s range is up to 60 yards. The recipient doesn’t know what hit them, often suspecting the prickly offender is a fly, Hatle said.

There was no serum in the demo dart because the drug costs $26 a pop, Inbody said.

The mares are not simply numbers on a list of suspects.

“They’re all named,” Hatle said. “That’s how we tell them apart.”

Dazzle didn’t cooperate Thursday.

To the right were the McCullough Peaks, looking grassy and inviting above U.S. Highway 14-16-20 (Greybull Highway). Behind rose Red Point, a butte with rusty striped horizontal stone lines and a pancake-flat top. A few hundred yards from her observers, Dazzle grazed with four other bands that Hatle refers to as the Red Point group.

Hatle and Inbody eased down to the herd, but each time they were nearly within range, the fickle mare would drift just out of range. The game of cat and mouse continued for about 15 minutes until the women threw in the hat, temporarily.

They have been darting horses since January. “We have many days like this,” Hatle said with a laugh. It takes patience and persistence.

“You have to keep trying,” she said.

If cattle were kept off, the range could support more wild horses. There were no grazing permit cattle on the range in 2012, and none this year. The bureau’s reason is to allow the land to recover from lack of precipitation in 2012, Martin said.

Thirteen domestic horses have been removed in the last three years after they were foisted on the herd. One man put his Nevada mustang in the McCullough herd, and he wound up with a $1,200 fine, Hatle said.

Domestic horses don’t fare so well fending for themselves in the wild and around a bunch of ornery wild horses that know the range ropes. Mustangs are a clannish, and clan hierarchy is strictly observed.

Domestics don’t understand mustang psychology, “so they really get beat up on,” Hatle said.

Allowing mares a chance to recover before impregnating them every year is improving their condition on a range with only fair conditions to begin with, Inbody said.