Population density and small-scale variation in habitat quality affect phenotypic quality in roe deer

We. tested for fine-scale spatial heterogeneity in habitat quality in a roe deer (Capreolus capreolus) population in the Chize reserve located in west ern France by measuring spatial variation in the availability and plant nit rogen content of principal and preferred plant species. There were signific ant differences in habitat quality within the reserve: the principal food p lants in spring and summer occurred more frequently in the oak woodland in the north than in the beech woodland in the south of the reserve. Within sp ecies, plants in the north had higher nitrogen contents than in the south. There was a positive spatial covariation between habitat quality, local den sity and fawn body weight: animal densities and fawn body weights were high est in the north, the best habitat (i.e. the habitat with more abundant foo d of higher quality). These results differ from those recently obtained on red deer (Cervus elaphus). We suggest that spatial organization and foragin g behaviour must be accounted for when considering, the effect of habitat q uality on individual fitness of ungulates.