Animal home range use is a central focus of ecological research. However, how and why home range size varies between individuals is not well studied or understood for most species. We develop a hierarchical analytical approach--using generalized linear mixed-effects modeling of time series of home range sizes--that allows variance in home range size to be decomposed into components due to variation in temporal, spatial, and individual-level processes, also facilitating intra- and interspecific comparative analyses. We applied the approach to data from a roe deer population radiotracked in central Italy. Over multiple timescales, temporal variation is explained by photoperiod and climate and spatial variation by the distribution of habitat types and spatial variance in radiotracking error. Differences between individuals explained a substantial amount of variance in home range size, but only a relatively minor part was explained by the individual attributes of sex and age. We conclude that the choice of temporal scale at which data are collected and the definition of home range can significantly influence biological inference. We suggest that the appropriate choice of scale and definition requires a good understanding of the ecology and life history of the study species. Our findings contrast with several common assumptions about roe deer behavior.

Wildlife management systems face growing challenges to cope with increasingly complex interactions between wildlife populations, the environment and human activities. In this position statement, we address the most important issues characterising current ungulate conservation and management in Europe. We present some key points arising from ecological research that may be critical for a reassessment of ungulate management in the future.

Ecological theory predicts that sympatric species should avoid competition through diet, spatial and/or temporal partitioning. In carnivores, interference is widespread between species with similar diets. Smaller species are expected to differentiate their diet from that of larger, dominant ones, to reduce the risk of potentially lethal encounters. Interference has been reported between tigers and common leopards, with the former dominant over the latter. In 2009–2011, in an area ofTerai,South‐WestNepal, we assessed food habits and prey selection of tigers and common leopards, to evaluate whether prey partitioning occurred between these large cats. Prey availability was high, both in terms of number of species (at least seven wild ungulates beside livestock, two primates and an array of smaller prey) and density (large ungulates, livestock and primates: 130.8–174.8 individuals per km²). Wild vertebrates were the staple of both cats (tigers: 82.7%; common leopards: 66.6%), but common leopards used livestock significantly more than tigers did. Diet breadth of leopards wasc.20% larger than that of tigers, indicating a broader trophic niche. Significant differences in prey use and selection occurred between tigers and leopards, with the former using large (i.e. >100 kg) prey more often and small (i.e. 5–25 kg) prey less often than the latter did. Medium‐sized prey were taken in comparable proportions by the two cats, with a great overlap of diet (Pianka index: 0.85). In conclusion, in our study area, apparently tigers and leopards did not base their coexistence on diet partitioning, suggesting a major role for spatial and/or temporal partitioning.

Resource exploitation and behavioural interference underlie competition among carnivores. Competition is reduced by specializing on different prey and/or spatio‐temporal separation, usually leading to different food habits. We predicted that two closely related species of large cats, the endangered snow leopard and the near‐threatened common leopard, living in sympatry, would coexist through habitat separation and exploitation of different prey species. In central Himalaya, we assessed (2006–2010) habitat and diet overlap between these carnivores. The snow leopard used grassland and shrubland, whereas the common leopard selected forest. Contrary to our prediction, snow leopard and common leopard preyed upon similar wild (Himalayan tahr, musk deer) and domestic species (Bos spp., dogs). Dietary overlap between snow leopard and common leopard was 69% (yearly), 76% (colder months) and 60% (warmer months). Thus, habitat separation should be the result of other factors, most likely avoidance of interspecific aggression. Habitat separation may not always lead to the use of different prey. Avoidance of interspecific aggression, rather than exploitation of different resources, could allow the coexistence of potentially competing large predators.