The federal government wants to find a couple of additional retirement homes for old mustangs.

The Bureau of Land Management is seeking bids to house up to 6,000 Western wild horses unlikely to be adopted because they are too old and because the agency needs to decrease the mustang population on rangeland, said spokesman Tom Gorey.

Although the BLM has 11 pasture refuges in Oklahoma, Kansas and South Dakota -- along with numerous short-term holding corrals, including three in Utah -- the agency is "maxed out," he said, with 30,000 mustangs in captivity.

The BLM is eyeing two types of pasture: one for 200 to 1,000 wild horses and one for 1,000 to 5,000 animals. Gorey said the agency would pay the landowner around $475 per horse per year.

The pasture plan has emerged since the BLM last year set aside an unpopular idea to euthanize horses instead of leaving them on the range. But critics have pounced on the latest proposal, too, arguing the high fertility rate in wild herds is a direct result of the BLM's disruption of natural behavior.

"This is a travesty," said Karen Sussman, president of the International Society for the Protection of Mustangs and Burros on the Cheyenne River Sioux Reservation in Lantry, S.D.

Sussman said her group has studied herd behavior and found that, when left to themselves, the horses don't multiply at the rate they do on public lands because the natural mare-to-stud ratio isn't disturbed.

Last year, it looked like the dilemma was solved when Madeleine Pickens, wife of natural-gas magnate T. Boone Pickens, said she would adopt 36,000 wild horses and put them on a million-acre sanctuary. That proposal stalled when she asked the BLM for a stipend that would go for the horse -- not the landowner, who might not use the money to care for the animal.

On Tuesday, Madeleine Pickens told The Salt Lake Tribune she wouldn't offer a bid to the BLM under its new proposal, but would continue to try to establish her own sanctuary.

"They just don't have any business sense," she said of the agency's wild-horse managers. "Any time you take an animal off its range you are responsible for it for the rest of its natural life."

Pickens said her refuge would be controlled by a nonprofit organization, and the land wouldn't pass down to her descendants. "This is a forever deal so those horses are taken care of."

Gorey said wild-horse herds double their population every four years. In 1971, the agency estimated there were 17,000 horses and 8,000 burros on the range. Now, there are more than 32,000 horses and about 3,800 burros. Gorey said the optimum free-roaming population is 26,000, given current range conditions.

Captured wild burros always are taken in by others, Gorey said, but horse adoptions are on the decline, leaving too many in what are supposed to be short-term holding pens. "Our goal, our ideal," he said, "is to put as many horses into private care as we take off the range. But we're not in that position."

Tammy Howell, a BLM wrangler at the Salt Lake Wild Horse & Burro Center in Herriman, said sorting out the pasture bids could take a year, because of environmental studies.

Right now, most of the horses in the Salt Lake Valley corrals are headed to the prison in Gunnison, where inmates gentle mustangs for private adoption.

Once the new pastures are open, Howell said, "we'd probably have some [mustangs] that would go there."

"I know there are people out there who believe we should just leave them out on the range," Howell added. "They would eat themselves out of house and home."

The wild horse and burro management budget is up $26.5 million from last year's $41 million, Gorey said, but it's still not enough.

Janet Tipton of the Intermountain Wild Horse & Burro Advisors Inc., a nonprofit volunteer organization in Tooele County that works with the BLM to gentle the animals, said keeping the wild horses on the range requires active management.

Arid conditions in the West force the horses to travel long distances for food and water. Some don't make it. "Starvation is a terrible way to die," Tipton said. "It takes forever and, to me, it's inhumane."

Moving aged horses to pastures is a good alternative, she said. "Give [them] a place where [they] know exactly where there's food and water all day. They graze in nice grass. They have shelter."