Does scale matter? The influence of threelevel spatial scales on forest bird occurrence in a tropical landscape.

Abstract

Consequences of habitat fragmentation for species occurrence are amongst the most important issues in landscape and conservation ecology. Empirical and theoretical studies have demonstrated that the total amount of habitat, patch size and connectivity have nonlinear effects on species survival on multiple spatial and temporal scales. Therefore, population models need to incorporate multiple scales, which can be extremely valuable to prioritizing conservation efforts in these changing landscapes. We tested how the amount and configuration of habitat affect understory bird species occurrence using fine to broadscale habitat features. We used playback to sample birds in 13 Atlantic Forest fragments in Southeast Brazil. Microhabitat, local and regional landscape variables were tested against bird occurrence. Our results demonstrate that different bird species respond to different habitat scales. Sclerurus scansor, Xiphorhynchus fuscus, Automolus leucophthalmus, Drymophila ochropyga, Mackenziaena leachii, and Chiroxiphia caudata were most influenced by tree height and diameter (microhabitat characteristics), S. scansor, F. serrana and Pyriglena leucoptera were most influenced by forest cover and red-edge reflectance(local-scale metrics) and S. scansor, X. fuscus, D. ochropyga, P. leucoptera, F. serrana and M. leachii had area, core area and functional connectivity index (landscape features) as stronger predictors of species occurrence. Small forest fragments acted as corridors and increased overall connectivity of the entire community. The most effective means of maintaining long-term population connectivity of understory birds involves retaining both large and small areas, including forests with different micro-habitat characteristics. No management approach based on a single-scale would benefit all species. Implementing multiscale conservation strategies are necessary for maintaining long-term viability of forest birds on tropical landscapes.