Who wants to live forever? Roe deer survival in a favourable environment

Abstract

AbstractThe survival rates and body masses of roe deer (Capreolus capreolus) were studied on the island of Storfosna in central Norway in relation to sex, age, season and year. There were no predators on the island, and hunting was halted during the study period, resulting in a population increase from 10 to 40 individuals per km2 during the period 1991–1994. A total of 352 individual roe deer were radio‐monitored on a monthly basis. Survival rates were analyzed using the MARK software. An age effect in survival was found separating fawns from yearlings and adults, and for yearlings and adults we furthermore found a year effect. There was evidence for density dependence in body masses of fawns and yearlings, but no density effect in survival rates. We found no sex effect in winter body mass, but a significant sex effect in survival rates. We conclude that (1) increased population density can have an effect on body masses without causing a change in survival rates (2) roe deer can maintain very high survival rates under favourable environmental conditions even at very high population densities (3) male adults can reach equally high survival rates as females under favourable circumstances.