RENO, Nev. (AP) — The U.S. Interior Department says it is reviewing a recent scientific report on the government's wild horse management program to explore "additional opportunities for population control."

The statement came in response to a letter to new U.S. Interior Secretary Sally Jewell by 30 U.S. Representatives, asking her to quickly reform the management program. The lawmakers say the program and its spiraling budget have created an "untenable situation" for both the mustangs and taxpayers.

A recent scientific review recommended that the government invest in widespread fertility control of the mustangs and let nature cull any excess herds instead of spending millions to house them in overflowing holding pens. There are an estimated 37,000 free-roaming wild horses and burros on federal land in the West.