Aim We aimed to describe the large-scale patterns in population density of roe deer Caprelous capreolus in Europe and to determine the factors shaping variation in their abundance. Location Europe.Methods We collated data on roe deer population density from 72 localities spanning 25°latitude and 48°longitude and analysed them in relation to a range of environmental factors: vegetation productivity (approximated by the fraction of photosynthetically active radiation) and forest cover as proxies for food supply, winter severity, summer drought and presence or absence of large predators (wolf, Canis lupus, and Eurasian lynx, Lynx lynx), hunter harvest and a competitor (red deer, Cervus elaphus). ResultsRoe deer abundance increased with the overall productivity of vegetation cover and with lower forest cover (sparser forest cover means that a higher proportion of overall plant productivity is allocated to ground vegetation and thus is available to roe deer). The effect of large predators was relatively weak in highly productive environments and in regions with mild climate, but increased markedly in regions with low vegetation productivity and harsh winters. Other potentially limiting factors (hunting, summer drought and competition with red deer) had no significant impact on roe deer abundance. Main conclusionsThe analyses revealed the combined effect of bottom-up and top-down control on roe deer: on a biogeographical scale, population abundance of roe deer has been shaped by food-related factors and large predators, with additive effects of the two species of predators. The results have implications for management of roe deer populations in Europe. First, an increase in roe deer abundance can be expected as environmental productivity increases due to climate change. Secondly, recovery plans for large carnivores should take environmental productivity and winter severity into account when predicting their impact on prey.

and Ettore CENTOFANTI Mattioli L., Apollonio M., Mazzarone V. and Centofanti E. 1995. Wolf food habits and wild ungulate availability in the Foreste Casentinesi National Park, Italy. Acta Theriologica 40: 387-402.We investigated wolf Canis lupus Linnaeus, 1758 food habits in northern Apennines by examining 240 scats collected between 1988 and 1992. In the same area we also estimated densities of the most common wild ungulates. Wild ungulates were the main prey of the wolf and accounted for more than 92% of both frequencies of occurrence and mean percentage volume. During our study period we observed a decrease in the use of roe deer and an increase in the use of wild boar. Moreover selection of wild boar by wolves increased too, but selection of roe deer decreased by almost 400%, with moderately fluctuating deer densities. The impact of predation was generally greatest on young animals. Roe deer fawns and red deer calves were predated 3.14 and 2.18 times respectively more than available. Wild boar also were predated mainly in their first year but more often from 6 months of age than before.

Predation by wolves Canis lupus on roe deer Capreolus capreolus was studied by scat analysis in five areas of the Province of Arezzo, north-eastern Tuscany, Italy. In the intensive study area (ISA) roe deer represented 19.1% of mean per cent volume (MPV) while in the other areas its use ranged between 10.9% and 53.4% of MPV. A low degree of variation was found in both annual and seasonal use of roe deer, although seasonal differences were more marked in those areas where roe deer use was lower. In ISA, roe deer was negatively selected among species: the Ivlev's electivity index ranged between − 0.41 and − 0.89. Analysing intra-specific selection, in ISA < 1-year-old individuals were preferred by wolves, mainly during the fawns' first months of life. This trend was confirmed in the other areas, where fawns represented more than 50% of the relative number of roe deer prey. In ISA, the use of roe deer (as MPV) was not correlated with its density or with that of the main prey, wild boar, and in almost all the other areas no relation between use and density of roe deer was founded. However, in the one area where both roe deer density and use were the highest, these two variables seemed to exhibit a comparable trend. The use of roe deer was negatively correlated with the percentage of forest cover among all the study areas.

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Studies on predation by the wolf (Canis lupus) have often reported contradictory results about the role of prey density and vulnerability on wolf prey use. We investigated dietary response and prey selection by wolves in a high-density and multi-species ungulate community, analysing scats collected over a period of 11 years in the Casentinesi Forests, Italy. The second most abundant species, wild boar (Sus scrofa), was found to be the main wolf prey, and we did not observe any dietary response of wolves to variations in the density of either primary or secondary prey species. Selection patterns were uniform throughout the study period. Wolves strongly selected for wild boar piglets, while roe deer (Capreolus capreolus) fawns and adults, red deer (Cervus elaphus) adults and fallow deer (Dama dama) adults were avoided. Wolf preference for wild boar was inversely density dependent. Within each species, juveniles were preferred to adults. Medium-sized, young individuals of both wild boar and roe deer were optimal prey, although with different selection patterns related to the different anti-predator strategies adopted by each prey species. The results of this study suggest that in productive ecosystems with high density and high renewal rates of prey, selection patterns by wolves are determined by prey vulnerability, which is connected to prey age and body size. The different patterns of wild boar versus cervids use by wolf across Europe seems to be related to their relative abundances, while the strong selection of wild boar in Italian Apennines with respect to the more frequent avoidance in central-eastern Europe is better explained by higher piglet productivity and smaller body size of adults boar in Mediterranean temperate forests.