Effect of climate and density on individual and population growth of roe deer Capreolus capreolus at northern latitudes: the Lier valley, Norway

The growth of individuals and populations can be affected by both density‐dependent and density‐independent factors. Severe environmental conditions typically affect young and very old individuals more than prime‐aged individuals, so that limiting factors such as climate and density frequently interact with the sex‐ and age‐structure of the population. For roe deer Capreolus capreolus explicit analyses of growth rates of individuals and populations at northern latitudes are rare. In this article, we present the first analysis of a 17‐year record of body weight data (N = 286) and harvest statistics (a proxy for population size) from the Lier valley, Norway. We tested whether climate (winter and spring) and population density affected individual body weight in autumn and the growth rate of the population as indicated by harvest statistics. We found that population growth rate in the Lier valley was negatively affected by increasing snow depth during winter. There was also a tendency for body weight to be lower after snowy than after less snowy winters. We found no significant effect of spring temperature or population density, though parameter estimates of both were negative. Our findings provide quantitative data supporting the ‘common knowledge’ that winter is the critical period for roe deer at northern latitudes, and that population density is unlikely to be a regulating factor in most inland areas of Norway with today's low population densities.