Nutritional ecology of roe deer (Capreolus capreolus L.) and fallow deer (Dama dama L.) : a case study of the browser - grazer dichotomy

Abstract: Nutritional ecology implies the nutritional links between an animal and its environment. On an evolutionary time scale competition for food drives species formation by genetic adaptations to the environment and subsequent niche separation of species. On a short-term scale, animals have different strategies in order to meet their nutritional requirements, which ultimately influence their health and fitness. These strategies differ among and within species while the nutritional, chemical, and structural composition of the forage varies across seasons. As such, different individuals may select particular amounts or proportion they consume based on stomach anatomy, metabolic rate, body size, physical states and life history. Understanding adaptations to different forage is therefore an important part of our understanding of nutritional ecology of herbivores, especially in temperate climate where herbivores adapt both physiologically and behaviorally to seasonal variations in order to meet their nutritional requirements. The aim of this project was to investigate temporal variation in chemical composition of forage between and within two cervid species. A total of 499 rumen samples collected from animals killed in the Koberg estate situated in southwestern Sweden were analyzed. Based on samples from fall, winter, spring and summer, the temporal variation of nutrient composition and interspecific differences between roe deer (Capreolus capreolus L.) and fallow deer (Dama dama L.) were investigated. The main results revealed that 1) the nutrient composition varied between species and across seasons so that roe deer selected higher proportion protein compared to fallow deer with highest proportions in spring 2) the nutrient composition varied across age and gender classes of fallow deer so that adult males selected lower proportion protein compared to female adults and juveniles in fall and 3) both species selected for a particular proportion of soluble carbohydrates, and that this proportion differed between gender and age classes within fallow deer so that adult females and subadult males selected for a particular proportion soluble carbohydrates compared to adult males. However, adult males selected for a stable proportion of protein in fall compared to adult females and subadult males. The results from this study can be used to understand inter- and intraspecific competition, to determine a correct carrying capacity of wildlife populations and to formulate balanced diets in order to avoid damages in agriculture and forestry.