VALE, Ore. -- The Bureau of Land Management is weighing whether to kill off thousands of wild horses now being kept in long-term holding plans.

Oregon Public Broadcasting reports that animal activists are unhappy about the plan.

There are an estimated 33,000 wild horses and burros in the western states.

BLM officials say that management goals allow, and is causing some environmental degradation.

Some horses are adopted out.

But in recent years there have been fewer adoptions since the cost of feeding and sheltering horses is so high.

Also, wild horse populations can double every four years.

So the BLM is considering killing some of these captive horses as population control.

Chris Heyde, a spokesman for the Animal Welfare Institute, says there are other ways to deal with the problem.

A decision on the proposal is expected by early October.