RELATIVE ROLES OF DENSITY-DEPENDENT AND DENSITY-INDEPENDENT FACTORS IN POPULATION-DYNAMICS OF BRITISH DEER

It has become increasingly clear that both density-dependent and densi ty-independent factors may influence the dynamics of mammalian populat ions; it remains more difficult, however, to determine which factors m ay play the more significant role in influencing population number in any particular case. In this paper we review published and unpublished data in an analysis of the various factors affecting population size and trend in three European species of deer: Red Deer (Cervus elaphus) , Fallow Deer (Dama dama) and Roe Deer (Capreolus capreolus). We selec t these species deliberately because they span a range of body size an d reproductive strategy - it seems that different demographic paramete rs might thus play different roles in the dynamics of the three-which may also be differentially sensitive to the effects of density-depende nt and density-independent factors. For each species we examine the av ailable evidence to determine the relative roles and effects of densit y-dependent feedback mechanisms and density-independent factors such a s climate on recruitment and mortality. Despite differences in bionomi c strategy between Red Deer (as essentially a K-strategist) and the mo re r-selected Roe, few differences emerge between the three species in the relative roles of density-dependent and density-independent facto rs - or of the stage at the life cycle at which each factor may act. O verall, however, it is clear that variation in density-independent fac tors, such as climate, appears primarily to affect levels of mortality within a population, while effects of density are particularly marked in relation to changes in recruitment.