Spectral landscapes show that responses to land-use change by aerial insectivorous bats are guild and scale dependent

Abstract

A central quest in conservation biology is to understand how wildlife responds to human-modified landscapes. Yet assessing features of transformed landscapes is non-trivial because categorical maps obscure ecologically meaningful transitions that organisms perceive continuously. We overcame this limitation by using satellite-based fine-scale continuous measures of landscape structure to examine how the cover, complexity, distribution and isolation of exposed and forested areas influence the composition of two guild of aerial insectivorous bats across multiple spatial scales. Although insectivorous bats provide key ecosystem services, it is still unclear which landscape features favor or reduce their abundance, and at what scales these effects occur. Our study was conducted in a heterogeneous agricultural mosaic in the central Andes of Colombia, ranging from well-preserved forests to open-pit mines. Bats that forage within forests or along edges were more abundant at sites with more forest cover but also where vegetation was more complex in terms of roughness and the presence of edges across all spatial scales. Contrary to our predictions, bats that forage in open spaces decreased in areas where exposed lands and fragments were dispersed and isolated at small spatial scales. At large spatial scales, open-space bats required abundant forest cover. These results show that insectivorous bats respond differently to landscape change depending on their ecology and movement behavior, and that these responses vary with spatial scale. Our findings highlight the value of using continuous landscape measures to better understand, manage, and conserve insectivorous bats in regions undergoing rapid land-use change.

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