Fluctuations of an Introduced Population of Svalbard Reindeer: The Effects of Density Dependence and Climatic Variation

The relative contribution of density-dependent and density-independent factors on variation in the population growth rate of an introduced population Svalbard reindeer was studied by time series analysis. No significant effects of either direct or delayed density-dependence were found. Annual variation in population growth rate was strongly negatively related to amount of precipitation during winter (i.e. high growth rates occurred when winters were dry). There was no significant relationship between the NAO-index and the population growth rate. However, there was an interaction between population density and the climatic variables, i.e. the effect of climate was stronger at high densities. These results support the view that population fluctuations of arctic ungulates are strongly influenced by stochastic variation in climate.