Meeting Abstract
Predators play a critical role in shaping ecosystems, driving both population and community dynamics. Traditionally, studies have focused on the direct effects of predators, namely the killing of prey. However, more recently, non-consumptive, risk effects of predators on prey are being appreciated. The risk of predation can induce morphological and behavioral trait changes in prey that are physiologically mediated, and often come at a cost to reproduction and survival. Previously, we provided the first evidence in a free-living mammal, snowshoe hares, that risk-induced maternal stress lowers reproduction and compromises the offspring’s stress axis (HPA-axis). Here we experimentally tested whether the risk of predation, acting via the stress axis, decreased survival of captively-held, wild hares. We exposed pregnant snowshoe hares to a live simulated predator (a trained dog that was not allowed to physically contact hares) for 1min every other day until parturition, and monitored survival of both mothers and offspring through to weaning. We found that females exposed to greater predation risk had higher stress hormone levels and greater mortality than control females. Further, we found that both pre-natal and post-natal mortality of offspring was higher even though risk exposure ceased at parturition, i.e., greater occurrence of abortion or stillbirth and higher mortality of viable offspring to weaning. Our results show, for the first time in a wild mammal, that in addition to direct killing, predators can increase the mortality of prey simply through risk effects. These findings have large implications to our understanding of predator-prey interactions and the influence of predators on population and community dynamics.
