Federal land managers have approved a summer roundup at Montana's Pryor Mountain Wild Horse Range to curb the size of its mustang herd.

The Bureau of Land Management announced Wednesday that it plans to remove 20 horses in 2015 and 6-12 horses annually in future years to reduce the size of the 170-animal herd.

The horses would be put up for adoption.

The Pryor herd is believed to be descended from horses used by Spanish Conquistadors. Roundups to reduce the herd take place periodically, with 700 horses removed since 1971.

The last took place in 2012, when 38 horses and six foals were removed to prevent overgrazing and other damage to the range.

The horse range established in 1968 includes 38,000 acres of public land near the Wyoming-Montana border.

MORE>>>Billings Gazette

Toads and frogs are calling out looking for mates across Montana, but some of them could be causing harm to Montana.

Adam Sepulveda with the U.S. Geological Survey wants people to know bullfrogs threaten Montana's waterways.

A lot of people, not just Montanans don't recognize that bullfrogs are a bad thing.

Bullfrogs are native to the eastern United States and since they were thought to be harmless, many were spread by humans across the western u.s., but recent evidence shows bullfrogs have an impact on native frogs across the West.

"In Montana we have a beautiful native frog, leopard frog. We know it is declining and we want to do what we can to help it persist, and we think that means controlling and when possible getting rid of bullfrogs," Sepulveda said.

Bullfrogs first found there way into Montana sometime in the 1920's and since then they have expanded their range across Western Montana.

But it was only in the last couple of decades they were found in eastern Montana. leaving Montana Fish, Wildlife and Parks wildlife managers concerned about stopping their spread further.

"I think at this point eradication that is not going to happen, so at this point what can we do about it is more about containment and prevention of introductions in other areas in eastern Montana," Sepulveda said.

Sepulveda and the USGS are looking at ways to curb the spread of bullfrogs, but the challenge will be getting people to understand the threat bullfrogs bring to Montana.

"They see them as a frog and they kind of think of being a 4-year-old running around with a net and being like it is fun to go around and catch them," Sepulveda .said.

Other Western States are also trying to curb bullfrogs impact on native frogs.

MORE>>>KPAX