Sheep losses to predators on a California range, 1973-1983.

Predation at the University of California Hopland Field Station was evaluated for an ll-year period beginning in 1973. Of those lambs placed on range, an average of 2.7% were killed each year by predators. An average of 1.5% of the ewes were killed. When the number of missing animals which were killed was estimated, the average annual predation rate for lambs and ewes killed was 10.4 and 3.8%, respectively. For all known ewe and lamb deaths, respectively, 45% and 26% were caused by predators, 14% and 28% died from causes other than predation, and 41% and 46% died from unknown causes. Of those sheep killed by predators, 89% were killed by coyotes (Canis r and superintendent and animal resource supervisor. University of California Hopland Field Station, 4070 University Road, Hopland, California 95449. I he authors thank D.M. Center. R.M. Dally. and C.E. Vaughn for reviewing the manuscript. Manuscript accepted November 20. 1984 livestock losses occurring during a few years. While short-term studies provide useful information, conclusions based on such research must be made with caution because factors such as predator density, environmental conditions, and availability of alternate prey vary annually and may influence predation. Generally, conclusions regarding livestock losses to predators are more reliable when long-term data are used; however, such data are rare. The purpose of this study was to evaluate livestock and economic losses to predators for a I l-year period beginning in 1973 for a. sheep operation in the northern coastal area of