Europe-wide consistency in density-dependence of red deer (Cervus elaphus) fertility

Population dynamics of large herbivores are affected by density dependent and density independent processes. Changing population size causes variation in age- and sex-specific demographic parameters such as reproduction, survival and dispersal. With our study, based on meta-analyses of literature data, we aimed at (1) describing age-specific fertility rates of red deer (Cervus elaphus) throughout Europe, and (2) tracking negative density feedback in reproduction of female red deer. Across the species range, in most European populations (84%) females began breeding as yearlings. We observed age-specific variation in female fertility, which was the lowest and most diverse in yearling females. Increasing population density had a negative effect on female fertility in all age groups. There was no difference in the strength of the relationship between different age classes of females. In 1.5-year old females, at low and moderate densities, fertility exhibited a high variation, which could indicate strong susceptibility of youngest females to detrimental external factors. Our study showed that meta-analysis of Europe-wide data was able to detect biologically relevant relationships which may be difficult to observe when applying locally-based and time-scale approach.