Evolutionary aspects of dietary selection and digestion in the European roe deer (Capreolus capreolus) with special reference to seasonality

Abstract

The European roe deer (Capreolus capreolus) is the smallest wild ruminant species in the northern hemisphere. Capreolini are represented in the fossil record of Eurasia by an array of forms extending from the Miocene to the Recent. Interestingly, a map of fossil occurrences shows that the historical range is fairly congruent with the recent distribution of Capreolus; roe deer have always been temperate-zone animals of Eurasia (Lister et al. 1998). In contrast to many other large herbivores the roe deer population in Europe increased both in terms of distribution and density during the last 100 years. This emphasises the flexible response of the species to rapidly changing environmental conditions and their potential to adapt to new resources in modern agriculture and forestry. This paper reviews aspects of evolution, dietary selection, digestion and adaptation of the European roe deer to the changing environment. In terms of feeding type, roe deer have been classified as a typical concentrate selector (Hofmann 1989), browsing on highly digestible plant parts. However, this feeding strategy can not be sustained during winter when forage is less available and its digestibility is reduced. Body reserves generally play no major role in roe deer (Holand 1992). Roe deer have developed several mechanisms to adapt to seasonal variations in their environment. It is the only ungulate that is strictly monestric with a genetically fixed diapause. Fawns are born in May when the quality of browse is at an optimum, and twins or even triplets are common. It is concluded that the perfect synchrony between seasonal changes of the resources and the demand due to reproductive investment may be the key function for the success of roe deer in temperate and northern climates.