Canids Specialist Group

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ResourcesUsing sterilized placeholders to deter interbreeding between red wolves and coyotes


The recovery and restoration of red wolves requires the careful management of coyotes in the red wolf recovery area in North Carolina.  The non-native coyotes were first observed in the reintroduction area in the early 1990s. Interbreeding between red wolves and coyotes produces hybrid offspring resulting in coyote gene introgression into the wild red wolf population, which threatens recovery goals.  An adaptive management plan (Kelly et al. 1999; Rabon et al. 2013) was developed by the U.S. Fish and Wildlife Service to reduce interbreeding and introgression while simultaneously building the red wolf population.  It effectively uses techniques to capture and sterilize hormonally intact coyotes via vasectomy or tubal ligation, then releases the sterile coyote at its place of capture to act as a territorial “placeholder” until the animal is replaced by dispersing red wolves.  Sterile coyotes are not capable of breeding, effectively limiting the growth of the coyote population, while also reducing hybridization with red wolves.  A sterile placeholder coyote also will exclude other coyotes from its territory.  Ultimately, the placeholder coyotes are replaced by the larger red wolves either naturally or via management actions (e.g., removal of the coyote followed by insertion of wild or translocated wolves).