Indirect food web interactions affect predation of Tengmalm's Owls Aegolius funereus nests by Pine Martens Martes martes according to the alternative prey hypothesis

摘要

Although population cycles of rodents are geographically widespread and occur in a number of rodent species, higher-order food web interactions mediated by predator-rodent dynamics have primarily been described from boreal and arctic biomes. During periods of low rodent abundance, predators may switch to alternative prey, which may affect other predators directly or indirectly. Using a long-term dataset, we assessed the frequency of Pine Marten Martes martes predation on the nests of Tengmalm's Owl Aegolius funereus during periods of fluctuating rodent abundance in Central Europe. The number of nests predated by Pine Martens was positively correlated with the annual number of nests available. The probability of predation by Pine Martens on Tengmalm's Owl nests decreased with increasing spring abundance index of Apodemus mice, but was not related to the abundance index of Myodes and Microtus voles, pooled rodent abundance or age of the nestbox. Additionally, we found no relationship between the breeding frequency (i.e. the number of nesting attempts per nestboxes available) and an abundance index of Microtus and Myodes voles, Apodemus mice or overall rodent abundance. Our results demonstrate, for the first time in a temperate area, that during periods of low Apodemus mouse abundance, the switching response of an opportunistic mammalian predator can lead to indirect food web interactions through an increase in nest predation on a sympatric avian predator.