To breed, or not to breed? Predation risk induces breeding suppression in common voles.

Breeding suppression hypothesis (BSH) predicts that, in several vole species, females will suppress breeding in response to high risk of mustelid predation; compared to breeding females, suppressing females would gain higher chances of survival. Seminal evidence for BSH was obtained in the laboratory, but attempts to replicate breeding suppression under field conditions were less conclusive. We tested whether breeding suppression occurs in common voles (Microtus arvalis), and how population density and predation risk combined affect voles' reproductive activity. We found that, in contrast to males, female common voles suppress reproductive activity when faced with high predation risk. Population size was not reduced despite breeding suppression. A model of the interaction between predation risk and population density revealed that predator-induced breeding suppression depends on the density of conspecifics. We concluded that breeding suppression is a viable adaptation only at low vole densities, when per capita predation risk is high. Finally, we identified the key issues of experimental design required for the consistency of future studies on breeding suppression.