Matrix type affects movement behavior of a Neotropical understory forest bird

Abstract

Fragmentation alters landscape structure and its relationship with organisms, where movement is one of the most affected processes. Movement choices are influenced by a cost and benefit evaluation, associated particularly to risks of predation and access to new resources. We analyzed the effect of matrix type on matrix-transfer success of a bird, Pyriglena leucoptera. We used a translocation-monitoring approach and evaluated time and trajectories used to reach an adjacent forest patch when released inside the matrix. The risk of predation was estimated by quantifying the density of birds of prey in three matrices (pastures, cornfields, and Eucalyptus) with different degrees of exposure given by differences in their vegetation structure. This variation was perceived by individuals, as evidenced by changes in their movement patterns and differences in their matrix-transfer success. The Eucalyptus, a low-risk matrix with the lowest density of predators and with more resources and shelters, resulted in tortuous movements by translocated birds. The pasture, an intermediate-risk with a wide visual field, resulted in straight and fast movements. The cornfields, a high-risk matrix with the highest density of predators and an increased obstruction of the visual field (when compared with pastures), resulted in more tortuous movements and longer exposure to risk, and thus in lower successful arrivals to forest patches. Our results highlight the importance of quantifying the effects of matrix type on movement behavior and on the persistence of species in fragmented landscapes. The proper management of matrices appears as a cost-effective option for improving connectivity in modified landscapes.