Effects of spatiotemporal variations in mortality on a migrating ungulate

Summary

Populations of several ungulate species are characterised by that a certain segment of the population, or the whole population, migrates between summer and winter ranges. In addition, ungulate populations suffer from various mortality factors, such as harvest, predation and traffic accidents. Mortality rate of various factors usually vary seasonally (e.g. harvest limited to a short period of the year) and spatially (e.g. predators only present in summer or winter range). The migratory movement is characteristic for most moose Alces alces populations. However, migration from summer to winter range might be almost absent in years without snow. In Norway, moose often migrate from the hills down to the valleys with less snow during winter. In the valleys we find roads and railway which results in a high number of moose-vehicle accidents during winter. In addition, the wolf (canis lupus) population is increasing in Norway, resulting in increased mortality rates particularly among young moose inside wolf pack territories. Here we present a model on how migration rates affect stationary moose inside wolf pack territories, which also are harvested in autumn and suffer from traffic accidents in winter.