High Emigration Propensity and Low Mortality on Transfer Drives Female-Biased Dispersal of Pyriglena leucoptera in Fragmented Landscapes.

Marcelo Awade,Carlos Candia-Gallardo,Jean Paul Metzger,Cintia Cornelius,Alessio Mortelliti

doi:10.1371/journal.pone.0170493

Marcelo Awade, Carlos Candia-Gallardo + Show 3 more

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https://doi.org/10.1371/journal.pone.0170493

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Abstract

Dispersal is a biological process performed in three stages: emigration, transfer and immigration. Intra-specific variation on dispersal behavior, such as sex-bias, is very common in nature, particularly in birds and mammals. However, dispersal is difficult to measure in the field and many hypotheses concerning the causes of sex-biased dispersal remain without empirical confirmation. An important limitation of most empirical studies is that inferences about sex-biased dispersal are based only on emigration proneness or immigration success data. Thus, we still do not know whether sex-biased immigration in fragmented landscapes occurs during emigration, transfer or in both stages. We conducted translocation and radiotracking experiments to assess i) whether inter-patch dispersal movements of a rainforest bird (Pyriglena leucoptera) is sex-biased and ii) how dispersal stages and the perceptual range of the individuals are integrated to generate dispersal patterns. Our results showed that inter-patch dispersal is sex-biased at all stages for P. leucoptera, as females not only exhibit a higher emigration propensity but are subjected to a lower risk of predation when moving through the matrix. Moreover, our data support a perceptual range of 80 m and our results showed that dispersal success decreases considerably when inter-patch distances exceeds this perceptual range. In this case, birds have a higher probability of travelling over longer routes and, as a consequence, the risk of predation increases, specially for males. Overall, results supported that assuming dispersal as a single-stage process to describe dispersal behavior may be misleading. In this way, our study advanced our understanding of processes and patterns related to inter-patch dispersal of neotropical forest birds, shedding light on potential implications for population dynamics and for the management of fragmented landscapes.

Highlights

Dispersal is a key concept in ecology and evolution and, probably, the most studied movement process in literature [1, 2]
We presented empirical evidence demonstrating that dispersal should be conceived as a three-stage process, otherwise we could not precisely describe the dispersal patterns of forest birds in fragmented landscapes neither understand the causes of these patterns
We presented strong evidence of a female-biased dispersal pattern for P. leucoptera, but we are still far from elucidating the effects of sex-biased dispersal on population dynamics in fragmented landscapes [57]

Summary

Introduction

Dispersal is a key concept in ecology and evolution and, probably, the most studied movement process in literature [1, 2]. Much theory was focused on determining the ultimate causes of dispersal [1, 2] and theoretical models derived from this background usually assume that all costs of dispersal are paid at emigration and these costs can be encapsulated into a single constant (i.e. an evolutionary stable dispersal rate [8]). This conception of dispersal has, at least, two limitations that have been hardly questioned in the recent literature. There is a growing theoretical and empirical literature demonstrating that spatial processes (e.g. habitat destruction and fragmentation) may affect the dispersal behavior of an individual [1, 2]

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