Periodic resource scarcity and potential for interspecific competition influences distribution of small carnivores in a seasonally dry tropical forest fragment

Abstract

Small, isolated, and disturbed forest fragments potentially offer valuable habitats for small carnivore conservation. Yet the influence of resource availability—critical for survival and reproduction—on small carnivore habitat use within these modified environments is poorly understood. We conducted camera-trap surveys within a seasonally dry tropical forest fragment (148 km2) in northeastern Thailand to better understand the influence resource availability has on small carnivore habitat use within fragmented areas. Species occupancy models including both habitat and resource variables were assessed across periods of high and low resource availability (fruit abundance and rodent biomass). Species with similar resource or habitat preferences may also compete when resources are low. Therefore, we tested species with shared preferences for patterns of spatial co-occurrence and temporal overlap. Fruit availability influenced the distribution of common palm civet (Paradoxurus hermaphroditus), while rodent biomass influenced Asiatic jackal (Canis aureus), leopard cat (Prionailurus bengalensis), and small Indian civet (Viverricula indica), but only during annual periods of scarcity. In contrast, small Asian mongoose (Herpestes javanicus) was highly selective for a specific habitat (dry dipterocarp forest) regardless of seasonal fluctuations in food availability. Occupancy increased for all species during periods of resource scarcity, with leopard cat and Asiatic jackal experiencing the greatest increases (139% and 58%, respectively). Species with shared resource and habitat preferences appeared to avoid each other, either spatially or temporally. For example, leopard cat and Asiatic jackal co-occurred spatially less than would be expected, though only when rodents were scarce. Similarly, small Indian civet and small Asian mongoose, which used the same habitat and co-occurred spatially at a rate greater than expected, were active at different times. Our results indicate that seasonal resource fluctuations and interspecific interactions strongly influence the distribution of sympatric small carnivores in a fragmented forest.