Aim Studies comparing feeding habits across a genus in different geographical regions or habitats can identify factors associated with adaptive feeding behaviour, linking key ecological traits between consumers and their environment. We investigated biogeographical patterns in dietary composition and trophic diversity across the genus Martes in relation to geographical range and environmental variables. We hypothesized that widely distributed opportunistic Martes species should demonstrate adaptive variations in dietary composition and trophic diversity relative to regional geographical location (e.g. latitude, elevation), environmental variation (e.g. temperature, rainfall, snow cover and primary productivity) and concomitant variation in food supply.Location Europe, Asia and North America.Methods We examined the dietary habits of martens (Martes spp.) using original data expressed as relative frequency of occurrence, and using principal components analysis to extract the main gradients in diet composition. These were then used as response variables in regression analyses, predicted from latitude or elevation. Multiple regression analyses were performed to assess the influence of food types and environmental variables on the trophic diversity index.Results A clear latitudinal gradient in dietary composition was observed. Small mammals were the primary food type, but were less abundant in the diet of martens at lower latitude and elevation. Vegetable matter and insects were consumed more frequently in southerly and/or lower-elevation localities. Trophic diversity was lower at higher elevation, and increased with a decline in consumption of the dominant food types, i.e. rodents, fruits and insects. Trophic diversity also increased with increasing mean temperature. Main conclusions Biogeographical variations in feeding habits across the genusMartes proved to be associated with latitude, local climate (especially temperature regime) and the availability of alternative potential foods. On an extensive geographical scale, martens respond to varying food availability by adjusting their foraging strategy and thus should be considered facultative generalists. At the species level, however, different climatic variables emerged as differentially important, indicative of adaptations to local conditions. Martes species are opportunistic and flexible feeders, and thus their conservation requires informed management, mindful of how changes in environmental conditions might influence their varied food supply.

The spatial and temporal distribution of food resources can profoundly affect foraging decisions and prey selection, potentially resulting in shifts in diet in response to changes in resource availability. The masked palm civet ( Paguma larvata ) has long been regarded as a dietary generalist that feeds primarily on fruits and small mammals. Both types of food resources may vary spatially and temporally and the diet of P. larvata is expected to change in response to variation in the availability and distribution of these resources. To address the effects of such variation on foraging by masked palm civets, we studied a population of P. larvata inhabiting a highly heterogeneous habitat in central China consisting of primary forest, selectively logged forest, logged forest, broad-leaved and coniferous forest plantations, and cultivated farmland. Available food resources included wild fruits, cultivated fruits, leaves, plant cortexes, amphibians, reptiles, birds, small mammals, molluscs, and arthropods. The abundance of these food categories varied significantly among seasons and habitats and civets altered consumption of these categories according to their temporal and spatial availability. The diversity of items consumed also varied significantly among seasons and habitats. From June to October, wild fruits were the main food of civets in forest habitats, whereas cultivated fruits were the main food in farmland. In contrast, from November to May, civets in forested habitats consumed primarily rodents and birds. Concordant with these changes was a shift from foraging in primary forest (November-May) to foraging in logged forest and farmland (June-October) that appeared to be associated with the availability of fruits. These results demonstrate the ability of civets to change their diet, both spatially and temporally, in response to changing food resources. To better understand how foraging behavior of civets varies with resource availability, similar studies should be conducted in tropical environments characterized by year-round availability of fruit.

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