Repellent or Aversive Chemicals in Sheep Neck Collars Did Not Deter Coyote Attacks

Since 1974 the Fish and Wildlife Service has studied a "toxic collar" to poison coyotes that attack collared sheep and goats. The collar patent (McBride 1974) indicates that the same collar could deliver chemicals to repel coyotes, thus saving both the coyote and the livestock. This report summarizes our experience with nonlethal tests of collars. During collar tests with 10 different toxicants, 21 coyotes received sublethal doses followed by aversive behavior or potentially aversive reactions. The subsequent predation history of these coyotes was examined for prey-avoidance. After a sublethal test, all coyotes killed lambs or kids in about 40 days, and 20 of 21 were eventually killed by another toxic collar. Limited testing with coyotes averted to salt flavor by lithium chloride-treated sheep bait also indicated poor protection of live sheep treated externally with salts (NaCl and LiCl). The results indicated little potential for using repellent or aversive chemicals in toxic collars or on sheep to repel coyotes.