caa a22 4500 463175972 CHVBK 20180406164826.0 cr unu---uuuuu 170326e20071001xx s 000 0 eng 10.1007/s10336-007-0189-2 doi (NATIONALLICENCE)springer-10.1007/s10336-007-0189-2 Consequences of sex-specific growth on sibling competition in black-headed gulls: a sexually-size dimorphic species with scramble competition [Elektronische Daten] [Wendt Müller, Ton Groothuis, Cor Dijkstra] Biased mortality of the larger sex during the early developmental period has been reported for a number of size-dimorphic bird species. This can partly be explained by the fact that growing to larger size renders the larger sex more vulnerable to food shortage. However, since sibling rivalry is often size-dependent, chicks of the larger sex should have a competitive advantage. This raises the question as to why the larger sex does not always benefit from its size in sibling competition. We studied sibling competition in the black-headed gull (Larus ridibundus), a sexually-size dimorphic species with male-biased mortality. We manipulated the natural brood sex ratio and placed one male chick in direct competition with one female chick while concurrently controlling for differences in age, size and laying order. Male chicks outgrew their female siblings by 15% in asymptotic body mass and did not suffer from enhanced mortality. Female chicks tended to be more alert when the parents returned to the nest and were more persistent in gull-typical begging displays. Females were more likely to get the first food item, but they did not get more food, possibly due to a size-mediated dominance over the non-monopolizable regurgitated food. Thus, it is unlikely that sex differences in competitiveness significantly contribute to male-biased mortality in black-headed gulls. The previously reported male-biased mortality is more likely due to a disadvantage of a higher food demand and a higher sensitivity towards low egg quality, as has been shown in previous studies. Dt. Ornithologen-Gesellschaft e.V., 2007 Begging nationallicence Egg quality nationallicence Growth rate nationallicence Hatching asynchrony nationallicence Sex ratio nationallicence Müller Wendt Research Group Behavioral Biology, University of Groningen, Groningen, The Netherlands aut Groothuis Ton Research Group Behavioral Biology, University of Groningen, Groningen, The Netherlands aut Dijkstra Cor Research Group Behavioral Biology, University of Groningen, Groningen, The Netherlands aut Journal of Ornithology Springer-Verlag 148/4(2007-10-01), 495-502 0021-8375 148:4<495 2007 148 10336 https://doi.org/10.1007/s10336-007-0189-2 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10336-007-0189-2 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Müller Wendt Research Group Behavioral Biology, University of Groningen, Groningen, The Netherlands aut NATIONALLICENCE 700 1- Groothuis Ton Research Group Behavioral Biology, University of Groningen, Groningen, The Netherlands aut NATIONALLICENCE 700 1- Dijkstra Cor Research Group Behavioral Biology, University of Groningen, Groningen, The Netherlands aut NATIONALLICENCE 773 0- Journal of Ornithology Springer-Verlag 148/4(2007-10-01), 495-502 0021-8375 148:4<495 2007 148 10336 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer