“The most complete data is from the Beaver Dam Mountains. Woodbury and Hardy reported a tortoise population density of 150 per square mile in 1948. BLM reduced cattle grazing a few years later and eliminated cattle in 1970. Coombs reported a tortoise density of 39 per square mile in 1974. In these 26 years cattle use was reduced 100 percent and tortoise numbers were reduced 74 percent.
“These tortoises were doing so poorly a veterinarian, Dr. Jarchow, was consulted. He reported all six specimens were suffering from osteoporosis caused by a protein deficiency in their diet. Dr. Jarchow examined five specimens from the same mountains that shared their range with cattle. He reported these specimens were all healthy and well nourished.
“The historical record proves conclusively that tortoise thrive when cattle are on the range with them and without cattle grazing they are always malnourished and unhealthy and their numbers plummet.
http://www.vinsuprynowicz.com/?p=80
A friend has a ranch in Oregon and runs on BLM land. Years ago he had to keep his cattle away from the creeks. And BLM cleaned up all of the “crap” in the creeks. Fallen timber, big boulders, etc. The rancher was trying to explain to them that the trout liked that “crap”. And having the cows in the creek stirs up the bottom and keeps it from getting silted in.
10 years later the BLM was back in after the trout numbers had dropped. I imagine they spent hundreds of thousands of dollars on studies. They put all of the “crap” back into the creeks and let him run cattle again. The trout bounced back.