Sheep-killing coyotes a continuing dilemma for ranchers

Abstract

Abstract: Predation on the Hopland Research and Extension Center's research sheep has increased substantially during the last several decades, as it did for commercial sheep producers in the North Coast region. Predator-caused losses in parts of the region reached unacceptable levels by the 1970s; concurrently, sheep inventories in Humboldt and Mendocino counties decreased dramatically. While domestic dogs, bears, golden eagles, and mountain lions have killed HREC sheep, approximately 75% of all predator-caused losses are due to coyotes. Lambs are more vulnerable to predation than are adult sheep, and at HREC, lamb loss approached or exceeded 10% of available lambs by the 1980s and approached or exceeded 20% three years during the 1990s. The Center evaluated a variety of lethal and nonlethal predator-control methods in an effort to find a predation control strategy that was cost effective and practical for other producers. Among the research approaches tested were potential coyote repellents, improved attractants for control devices, guard dogs and guard llamas, and electric fencing. These strategies, even when used in combination with assistance from the local predator control specialist, did not prevent significant losses of lambs and adult sheep. The most promising strategy tested was selective removal of only sheep-killing coyotes by use of the livestock protection collar containing sodium fluoroacetate. Selective removal of only sheep-killing coyotes, using this tool, resulted in successful reduction in lamb losses during the late 1990s. However, a November 1998 ballot initiative, "Proposition 4," banned all uses of sodium fluoroacetate as well as leghold traps in California, with no provisions for their research uses. This measure made it increasingly difficult to achieve effective control of predation on the Center's research sheep flock.