Abstract
Seasonality causes fluctuations in resource availability, affecting the presence and abundance of animal species. The impacts of these oscillations on wildlife populations can be exacerbated by habitat fragmentation. We assessed differences in bat species abundance between the wet and dry season in a fragmented landscape in the Central Amazon characterized by primary forest fragments embedded in a secondary forest matrix. We also evaluated whether the relative importance of local vegetation structure versus landscape characteristics (composition and configuration) in shaping bat abundance patterns varied between seasons. Our working hypotheses were that abundance responses are species as well as season specific, and that in the wet season, local vegetation structure is a stronger determinant of bat abundance than landscape‐scale attributes. Generalized linear mixed‐effects models in combination with hierarchical partitioning revealed that relationships between species abundances and local vegetation structure and landscape characteristics were both season specific and scale dependent. Overall, landscape characteristics were more important than local vegetation characteristics, suggesting that landscape structure is likely to play an even more important role in landscapes with higher fragment‐matrix contrast. Responses varied between frugivores and animalivores. In the dry season, frugivores responded more to compositional metrics, whereas during the wet season, local and configurational metrics were more important. Animalivores showed similar patterns in both seasons, responding to the same group of metrics in both seasons. Differences in responses likely reflect seasonal differences in the phenology of flowering and fruiting between primary and secondary forests, which affected the foraging behavior and habitat use of bats. Management actions should encompass multiscale approaches to account for the idiosyncratic responses of species to seasonal variation in resource abundance and consequently to local and landscape scale attributes.
Highlights
Throughout the tropics, high rates of deforestation have drastically increased the number of old-growth forest patches surrounded by an anthropogenically modified matrix (Melo, Arroyo-R odríguez, Fahrig, Martínez-Ramos, & Tabarelli, 2013)
Three species responded to the same group of metrics in both seasons, L. silvicolum to configuration and P. parnellii and M. crenulatum to composition, suggesting that for animalivores, seasonality and the variability in resource availability may not play such an important role as it does for frugivores
Our results show that seasonality affected the responses of bat species to local vegetation structure and landscape characteristics
Summary
Throughout the tropics, high rates of deforestation have drastically increased the number of old-growth forest patches surrounded by an anthropogenically modified matrix (Melo, Arroyo-R odríguez, Fahrig, Martínez-Ramos, & Tabarelli, 2013). We anticipated local vegetation structure to play a greater role than landscape structure in the wet season, due to higher food availability and smaller home ranges of bats during this period (Haugaasen & Peres, 2005; Klingbeil & Willig, 2010). These patterns would reflect the reproductive cycle of bat species, the availability, and distribution of food resources across the landscape and the differential ability of species to exploit the resources in the secondary forest matrix. We predicted that abundances of frugivores in secondary forest would be higher than those of animalivores, that abundances will be more similar to those in continuous forest with increasing successional stage of secondary forest, following the gradient of increasing similarity in vegetation structure and composition
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