The cost of migratory prey: seasonal changes in semi-domesticreindeer distribution influences breeding success of Eurasian lynx in northern Norway

Abstract

Migratory prey is a widespread phenomenon that has implications for predator – prey interactions. By creating large temporal variation in resource availability between seasons it becomes challenging for carnivores to secure a regular year-round supply of food. Some predators may respond by following their migratory prey, however, most predators are sedentary and experience strong seasonal variation in resource availability. Increased predation on alternative prey may dampen such seasonal resource fl uctuations, but reduced reproduction rates in predators is a predicted consequence of migratory primary prey behavior that has received little empirical attention. We used data from 23 GPS collared Eurasian lynx Lynx lynx monitored during 2007 – 2013 in northern Norway, to examine how spatio-temporal variation in the migratory behavior of semi-domestic reindeer Rangifer tarandus infl uences lynx spatial organization and reproductive success using estimates of seasonal home range overlap and breeding success. We found that lynx of both sexes maintained seasonally stable home ranges and exhibited site fi delity across years, independent of whether they had access to reindeer throughout the year or experienced a scarcity of reindeer in winter due to migration. However, lynx without access to reindeer in winter showed a decreased probability of reproducing and a tendency for lowered kitten survival into their fi rst winter, when compared to female lynx with reindeer available year around. Th is supports the hypothesis that sedentary predators experience demographic costs in systems with migratory primary prey. Changes in the migratory behavior of ungulates, including disrupted migrations, is therefore likely to have bottom – up eff ects on the population dynamics of sedentary predators as well as the previously documented consequences for ungulate population dynamics.