283 Folia Zool. – 57(3): 283–293 (2008) White-tailed deer winter feeding strategy in area shared with other deer species Miloslav HoMolka 1 , Marta Heroldová 1 and Ludk Bartoš 2 1 Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic,v.v.i., Květná 8, CZ-603 65 Brno, Czech Republic; e-mail: homolka@ivb.cz 2 Department of Ethology, Institute of Animal Science, P.O.B. 1, CZ-104 01 Praha 10 Uhříněves, Czech Republic received 25 January 2008, accepted 9 June 2008 abstr a c t . White-tailed deer were introduced into the Czech republic about one hundred years ago. Population numbers have remained stable at low density despite almost no harvesting. this differs from other introductions of this species in europe. We presumed that one of the possible factors preventing expansion of the white-tailed deer population is lack of high-quality food components in an area overpopulated by sympatric roe, fallow and red deer. We analyzed the Wtd winter diet and diets of the other deer species to get information on their feeding strategy during a critical period of a year. We focused primarily on conifer needle consumption, a generally accepted indicator of starvation and on bramble leaves as an indicator of high-quality items. We tested the following hypotheses: (1) If the environment has a limited food supply, the poorest competitors of the four deer species will have the highest proportion of conifer needles in the diet ; (2) the deer will overlap in trophic niches and will share limited nutritious resource (bramble). White-tailed, roe, fallow, and red deer diets were investigated by microscopic analysis of plant remains in their faeces. the volume of bramble decreased in the diet of all four deer species from November to March. the content of conifer needles in the diet of white-tailed and roe deer was negatively correlated with bramble and in spring made up 90 % of their diet volume. on the other hand conifer needles in the diet of red and fallow deer occurred only in January with snow cover. Fallow and red deer started the compensation of winter starvation at least one month earlier than both roe and white-tailed deer. a high content of conifers in white-tailed deer diet in the second half of the winter fully support the presumption about low nutritional food supply and its diet. It can lead to a markedly impaired condition for white-tailed and roe deer and negatively affect their condition. the dietary overlap of four sympatric deer species was extensive in winter. All species share a limited good quality food supply (bramble) when food is scarce, suggesting that interspecific competition may occur. Key words: Capreolus capreolus, Cervus elaphus, Czech republic, Dama dama, diet analysis, fallow deer, Odocoileus virginianus, red deer, roe deer Introduction White-tailed deer (Wtd), Odocoileus virginianus, were introduced into the Dobíš Forest, Central Bohemia, Czech republic, about one hundred years ago (Andra & H a n z a l 1995). Population numbers (around 250 head) have remained stable for at least the last 30 years and the deer have not tended to spread into other localities. In comparison with the results of other introductions of this species in europe, e.g., into Finland (M o i l a n e n 1968, N y g r é n 1984, t i a i n e n 1989), it is curious that the Dobíš population has remained so localized despite the continued interest on the part of hunters in increasing its numbers. one of the possible factors that may negatively affect the development of the Wtd population is insufficient food supply, during winter in particular, reflected in poor physical