A helicopter helps in a roundup of wild burros Thursday near Crystal. The burros will be taken to holding facilities in California and Northern Nevada. Activists contend the thinning of herds of burros and wild horses is based on inaccurate environmental data. Photos by Gary Thompson. Wranglers working for the Bureau of Land Management round up a wild burro Thursday near Crystal, 70 miles northwest of Las Vegas. Officials say they are thinning the herds to levels appropriate for the environment. A wild burro, one of 16 rounded up Thursday, eyes one of the wranglers who helped in the gather.

CRYSTAL

With helicopter blades whirling several feet above their perked ears and wranglers on their heels, nearly a dozen wild burros bolted between two hemp fences Thursday that funneled them into a trailer ready to haul them off the range.

It was the second sweep of the morning, and the two sweeps rounded up 16 burros in all -- jennies, jacks and their young -- in a gather that is expected to remove 780 burros and 266 wild horses from three herd areas in the Spring Mountains.

The gather includes the Thursday effort on the Johnnie herd area, 70 miles northwest of Las Vegas, and ones to follow with the Red Rock and Wheeler Pass herds on Bureau of Land Management and U.S. Forest Service lands near Cold Creek and Red Rock Canyon.

The $400,000 endeavor led by the Bureau of Land Management is designed to thin the herds to an appropriate level that officials said fits the forage and water available on the ranges.

The goal is to bring them in balance with the environment while keeping an adequate ratio between sexes and ages to maintain a viable herd, BLM spokeswoman Kirsten Cannon said.

But in court papers filed Thursday, the second day of the gather, attorneys for activists sought again to stop the procedure.

They said the government's environmental assessment that supports the gather is "flawed, inaccurate and being improperly used."

Also, the amended lawsuit, filed by attorneys John E. Cereso and Louis C. Schneider for America's Wild Horse Advocates, contends that some herd size estimates were made by inexperienced observers.

They wrote that the BLM and the Forest Service disagree on what the herd sizes should be and that the roundups "will harm the genetic viability and diversity of the herds in the Spring Mountain Range areas."

Juan Palma, the BLM's Las Vegas Field Office manager, had no comment on the amended lawsuit, which followed the original filing Dec. 26 in U.S. District Court. A request for an emergency temporary restraining order was denied last week.

At Thursday's gather, Forest Service Natural Resource Officer Amy Meketi said data collected in August and September on range conditions around Cold Creek, where wild horses will be rounded up next week, found that horses and elk use 80 percent of the available forage. The Forest Service management plan calls for 30 percent use.

That means the Wheeler Pass herd of 268 wild horses and 126 burros will be trimmed to 47 and 21, respectively.

Likewise, Cannon said, the 573 burros and 85 horses in the Johnnie herd will be reduced to 60 and 40 respectively.

In the Red Rock herd, no wild horses will be removed, leaving 25, including four foals, but the number of burros will drop from 201 to 40.

In all, out of 374 horses and 900 burros in the three herd areas, 112 horses and 121 burros will remain in the Spring Mountains after the roundup.

Horses that are returned to the range will be inoculated for birth control. Birth control methods for burros have not been tested, Cannon said.

She said that with birth control, the reproduction rate for wild horses will drop from 20 percent to 5 percent.

The animals will be transported to holding facilities at Ridgecrest and Litchfield in California and at Palomino Valley near Sparks.

Billie Young, president of the nonprofit America's Wild Horse Advocates, said the numbers of animals to be removed from the ranges "are not a true example of a viable herd."

Young said that some removal of animals should take place but contended a valid scientific study would result in more of them being allowed to stay on the range.

Those that are left no longer can migrate and integrate with those in other herds because of fences and other barriers, Young said.

"We don't believe there is integrity in their data to support their actions," she said. "Once the animals are processed, it will be impossible to get them back. They will be gone forever."