Data from: Sex-specific arrival times on the breeding grounds: hybridizing migratory skuas provide empirical support for the role of sex ratios

• Main Authors: Lisovski, Simeon, Fröhlich, Anne, von Tersch, Matthew, Klaassen, Marcel, Peter, Hans-Ulrich, Ritz, Markus S.
• Format: Dataset
• Language: unknown
• Published: Dryad 2020
• Subjects: sex-role reversal; Catharacta maccormicki; Catharacta; Catharacta antarctica lonnbergi; Migration; population sex ratio; Spring migration; arrival dates; Antarctica; Life sciences; medicine and health care; envir; geo; King George Island; Anvers; Antarc*; South Polar Skuas
• Online Access: https://doi.org/10.5061/dryad.6v5g3

In migratory animals, protandry (earlier arrival of males on the breeding grounds) prevails over protogyny (females preceding males). In theory, sex differences in timing of arrival should be driven by the operational sex ratio, shifting toward protogyny in female-biased populations. However, empirical support for this hypothesis is, to date, lacking. To test this hypothesis, we analyzed arrival data from three populations of the long-distance migratory south polar skua (Catharacta maccormicki). These populations differed in their operational sex ratio caused by the unidirectional hybridization of male south polar skuas with female brown skuas (Catharacta antarctica lonnbergi). We found that arrival times were protandrous in allopatry, shifting toward protogyny in female-biased populations when breeding in sympatry. This unique observation is consistent with theoretical predictions that sex-specific arrival times should be influenced by sex ratio and that protogyny should be observed in populations with female-biased operational sex ratio. DataArrival dates of South Polar Skuas and Brown Skuas at King George Island and Anvers IslandR codeIndividual based model to simulate sex specific arrival timesskua.IBM.R