Brown bear food habits in natural and human-modified landscapes in West-European Russia

Abstract: Brown bear (Ursus arctos) diet composition and seasonal food habits were examined in the Central Forest Nature Reserve (CFNR) in West-European Russia. This territory has 2 landscape types: (1) a mostly intact and strictly protected CFNR core area with southern taiga forests, and (2) a human-modified buffer zone around it. We collected 758 bear scats between March and November 2008–2021. Fleshy fruits were the most important food category in the bear diet and represented 30% of the annual estimated dietary energy content (EDEC). Among fruits, the most important food items were apples (Malus domestica; EDEC = 22%). Bears highly preferred bilberry (Vaccinium myrtillus) in the late summer and early fall seasons (EDEC = 9%). During the hyperphagia period, bears fed on apples, hazel nuts (Corylus avellana; EDEC = 17%), oat (Avena sativa; EDEC = 9%), rowan (Sorbus aucuparia; EDEC = 5%), and cranberry (V. microcarpum and V. oxycoccos; EDEC = 4%). Herbaceous plants were also important (EDEC = 6%) from late spring to early fall. Among insects, bears actively consumed ants (Formicidae; EDEC = 3%) and social wasps (Vespidae; EDEC = 3%). Ungulates, especially adult moose (Alces alces) and calves, comprised the most important food item for bears during spring, contributing 15% of the EDEC. The CFNR core area, which presents natural foods for bears, had a prevalence of bilberry in scat amount (Cliff's Delta = –0.20). The buffer zone had a prevalence of apples (Cliff's Delta = 0.19) and oat (Cliff's Delta = 0.14), whose distributions were associated with abandoned orchards and cultivated fields. Brown bear food habits in the CFNR are similar to those in southern and eastern Europe, with a great dietary contribution of plant materials (especially fleshy fruits and hard mast). However, at the same time, CFNR bears have a significant dietary impact associated with boreal ecosystems (high Vaccinium berry consumption and active moose hunting), which makes it similar to populations from northern Europe.