Seasonal and specific diet variations in sympatric red and fallow deer of southern Spain: a preliminary approach to feeding behaviour

Abstract

We studied the diet composition and diet overlap in sympatric red deer (Cervus elaphus hispanicus) and fallow deer (Dama dama) throughout a whole year in order to determine variation due to season, species, sex and age class by analysing rumen contents samples of 81 red and 69 fallow deer shot monthly during 2008–09 in Sierra de Andújar Natural Park, southern Spain. We assessed diet similarity and possible inter- and intra-specific foraging competition. We found different foraging strategies for both species and sexes during constraint periods, and several theoretical considerations of specific interactions and behaviour are discussed with respect to the Mediterranean environment. In both species an annual diet dominated by grasses was recorded, peaking in spring. Browses were an important food resource at the end of winter and at the end of summer, and fruit more in autumn and winter. Red deer ingested a higher proportion of browse than fallow deer, which consumed more acorns and for a longer time showed a better ability to compensate for nutritional constraint periods. An overall decline in diet similarity in summer and at the end of winter led us to assume that exploitative competition between red and fallow deer and even between sexes was probable. Red deer females showed low diet similarity to other deer, while there was a great diet overlap between red deer males and fallow deer females at the end of summer. Differences detected between both two species and sexes do not always support predictions deriving from specific body size and morpho-physiological characteristics, but can probably be explained as a consequence of different metabolic demands. The relationship between plant nutritional attributes and food selection according to reproductive or physiological status and seasonal demands for both sexes and species should be researched in order to perform a better assessment of deer feeding behaviour.