Wild horse managers are rounding up horses in southwest Wyoming this week and through September in an effort to drastically reduce the number of horses on certain public lands.

Alan Shepherd, wild horse program lead for the Bureau of Land Management in Wyoming, said there are now about 1,200 horses in Adobe Town in southern Sweetwater County, and the agency aims to gather 1,000. Of those, 600 will be removed from the population and put into the adoption program. The rest will be released in other areas.

Another roundup is planned to begin Labor Day in the Salt Wells Creek area, also in southern Sweetwater County, where there are now about 625 horses. About 500 will be gathered, and 300 will be removed.

The planned sharp reduction in wild horse populations has caused consternation among horse advocates.

Shepherd said the BLM has an agreement with the state and a court order saying it will manage for the minimum "appropriate management levels." The range of numbers for Adobe Town is 610 to 800 horses; at Salt Creek, numbers range from 251 to 365. So the agency is rounding up horses to leave herds at the bottom of the range.

"When we do a gather to control populations, we remove down to the low end and allow it to build up over a period of three to four years," Shepherd said. "We allow them to have an increase over a period of time then take the population down to the low end of the range."

Pat Fazio, statewide coordinator of the Wyoming Animal Network, said there is a "huge problem" with the BLM's appropriate management levels.

"They set the numbers arbitrarily and capriciously really without some really good range data or censusing," Fazio said.

Fazio also said the number of wild horses nationwide has been decreasing steadily. Numbers are now nearly as low as they were in 1959, when some of the first protections of wild horses were enacted by Congress.

Wild horse numbers nationwide have dipped from a 1978 high of about 57,000 animals to about 27,000 today. The BLM will hold 57 roundups this year in nine Western states. In the past three years, the agency has removed 10,000 horses each year from federal lands, according to The Associated Press.

Wyoming is home to about 4,100 wild horses in 16 management areas. BLM's objective is between 2,500 and 3,600 animals.

Shepherd said numbers were established through monitoring and through public process. Current numbers were established between 1992 and 1995, he said. Those numbers are not outdated, Shepherd said, because they are "pretty close" to the monitoring data the agency has for the horse herd areas.

Horse populations increase rapidly, according to the Shepherd and the BLM. In February 2004 in Adobe Town, there were estimated to be 839 horses. In Salt Creek at the same time, numbers hovered around 405. A 40 percent increase in a year is not unusual, Shepherd said.

"They're a prolific animal," he said. "That's why we have to do management actions every few years."

In 2003, Gov. Dave Freudenthal threatened to sue the BLM to manage horses for minimum numbers, saying in part excess horses were hurting their own species and curtailing grazing leases on federal lands. The state and the BLM then entered a consent decree, which is guiding the latest roundups.

Meanwhile, wild horse advocates are suing the BLM, saying its calls to reduce horse herds are done without adequate science. A federal judge in Washington, D.C., last year rejected that case, and it is now in appeal. Oral arguments are expected Sept. 26.

In October, the BLM intends to conduct more roundups near Lander. The Green Mountain herd holds 670 wild horses, and officials hope to reduce that to 170.

Environmental reporter Whitney Royster can be reached at (307) 734-0260 or at royster@trib.com.