Apparent competition, or predator selection for rare secondary prey instead of abundant primary prey, is causing prey declines in many species worldwide. The causal mechanism for apparent competition is either lower intrinsic growth rate in the secondary prey or higher disproportionate predation by predators for secondary prey. Harvest regimes which target male carnivores are now widely accepted to result in increased sexually selected infanticide (SSI) because of rapid male turnover and immigration by non-sire males, and sexually segregated habitat use because of female avoidance of infanticidal males. If harvest regimes which target male mountain lions cause increased SSI and sexually segregated habitat use by females with young, it could also cause inverse prey switching by females with young or apparent competition in declining secondary prey. We tested for inverse prey switching by female mountain lions with young - from abundant increasing white-tailed deer at low elevations to declining mule deer at high elevations in a heavily hunted, sexually segregated population of mountain lions. The "no effect of targeted male harvest" hypothesis predicts that none or all sexes and reproductive classes of mountain lions will select for mule deer. The "targeted male harvest effect" hypothesis predicts that only females with young will select for declining mule deer. We rejected the "no effect of targeted male harvest" hypothesis and accepted the "targeted male harvest effect" hypothesis because only females with cubs selected for declining mule deer at high elevations and only during summer, when kittens were vulnerable to infanticide - other sex and reproductive classes selected for abundant increasing white-tailed deer at low elevations. We suggest that harvest regimes which focus on male harvest to reduce predation on declining secondary prey could be causing increased predation on declining secondary prey elsewhere.
Keehner, J. R., Wielgus, R. B., & Keehner, A. M. (2015). Effects of male targeted harvest regimes on prey switching by female mountain lions: Implications for apparent competition on declining secondary prey. Biological Conservation, 192, 101–108. https://doi.org/10.1016/j.biocon.2015.09.006