Sex‐specific winter distribution in a sexually dimorphic shorebird is explained by resource partitioning

Ecology and Evolution

Sjoerd Duijns¹  Jan A. van Gils¹  Bernard Spaans¹  Job ten Horn¹  Maarten Brugge¹ 

[1] Department of Marine Ecology, NIOZ, Royal Netherlands Institute for Sea Research, Den Burg, Texel, The Netherlands

关键词: Bergmann's rule;    habitat selection;    intertidal ecology;    Limosa lapponica;    prey accessibility;    sexual size dimorphism (SSD);   

DOI  :  10.1002/ece3.1213

来源: Wiley

【 摘 要 】

Abstract

Sexual size dimorphism (SSD) implies correlated differences in energetic requirements and feeding opportunities, such that sexes will face different trade-offs in habitat selection. In seasonal migrants, this could result in a differential spatial distribution across the wintering range. To identify the ecological causes of sexual spatial segregation, we studied a sexually dimorphic shorebird, the bar-tailed godwit Limosa lapponica, in which females have a larger body and a longer bill than males. With respect to the trade-offs that these migratory shorebirds experience in their choice of wintering area, northern and colder wintering sites have the benefit of being closer to the Arctic breeding grounds. According to Bergmann's rule, the larger females should incur lower energetic costs per unit of body mass over males, helping them to winter in the cold. However, as the sexes have rather different bill lengths, differences in sex-specific wintering sites could also be due to the vertical distribution of their buried prey, that is, resource partitioning. Here, in a comparison between six main intertidal wintering areas across the entire winter range of the lapponica subspecies in northwest Europe, we show that the percentage of females between sites was not correlated with the cost of wintering, but was positively correlated with the biomass in the bottom layer and negatively with the biomass in the top layer. We conclude that resource partitioning, rather than relative expenditure advantages, best explains the differential spatial distribution of male and female bar-tailed godwits across northwest Europe.

【 授权许可】

CC BY   
© 2014 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.