This story is from the Reno Gazette Journal. By Jeff DeLong
The cougar may be preying largely on the foals of wild horses in the Virginia Mountain range of extreme Western Nevada. It has been fitted with a radio-collar to see if this seemingly rare kind of predation is taking place.
Ralph Maughan
Dr. Ralph Maughan is professor emeritus of political science at Idaho State University. He has been a Western Watersheds Project Board Member off and on for many years, and also its President. For many years he produced Ralph Maughan's Wolf Report. He was a founder of the Greater Yellowstone Coalition. He and Jackie Johnson Maughan wrote three editions of "Hiking Idaho." He also wrote "Beyond the Tetons" and "Backpacking Wyoming's Teton and Washakie Wilderness." He created and is the administrator of The Wildlife News.
This may not be that unusual, though maybe it is a skil developed by individual cats. About 3 years ago in the Pryor Mnt wild horse herd a female mountian lion with 2 yearling male cubs was given responsibility for killing 24 of that years 28 foals. As was hoped, when the young toms disperesed, predation seems to have declined, but seeing horses with scars that are probably lion caused is common.
According to reports I’ve read, some of the Kiger Mustangs of the Oregon desert bear scars from aborted lion attacks. One in particular, a stallion nicknamed Rojo, is famously identified by such battle wounds.
http://www.kyhorsepark.com/imh/bw/kiger.html#signif
I would imagine, however, that mountain lions only rarely target adult horses, which would be formidable targets unless handicapped by age or injury. What I wonder about is the potential interaction of gray wolf and wild horse. If wolves ever recolonize a place like the Red Desert, at what proportion will feral horses figure into their annual diet?
For a contrarian view of wild horses: http://audubonmagazine.org/incite/incite0609.html