caa a22 4500 463176235 CHVBK 20180406164827.0 cr unu---uuuuu 170326e20070401xx s 000 0 eng 10.1007/s10336-006-0121-1 doi (NATIONALLICENCE)springer-10.1007/s10336-006-0121-1 Seasonal decline in cell-mediated immunity of collared flycatcher Ficedula albicollis nestlings: does the sex of offspring matter? [Elektronische Daten] [Tomasz Wilk, Anna Dubiec, Mariusz Cichoń] The seasonal decline in offspring performance is a frequently reported phenomenon in species breeding in a temperate zone, but the potential effect of brood sex ratio on such declines has not been studied. Here, we predicted that this decline may occur if the sex that exhibits the lower immune response or lower survival rate tends to be more frequent among late broods. The seasonal patterns of four performance parameters of collared flycatcher Ficedula albicollis nestlings have been examined during 4years. Sex was assigned to all studied individuals using molecular techniques. We found significant seasonal decline in cell-mediated immune response, tarsus length and survival of the chicks. The lack of interactions between gender and hatching date revealed that both sexes contributed equally to the observed decline. The brood sex ratio did not vary with the laying date. On the basis of available data, we suggest that the breeding date may only exceptionally induce female-driven sex allocation in species with only slight sexual size dimorphism. In consequence, we suggest that seasonal sex ratio shifts do not account for seasonally declining fitness of nestlings in passerines. Dt. Ornithologen-Gesellschaft e.V., 2006 Ficedula albicollis nationallicence Immune response nationallicence Phytohaemagglutinin nationallicence Seasonal decline nationallicence Sex ratio nationallicence Wilk Tomasz Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland aut Dubiec Anna Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland aut Cichoń Mariusz Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland aut Journal of Ornithology Springer-Verlag 148/2(2007-04-01), 199-205 0021-8375 148:2<199 2007 148 10336 https://doi.org/10.1007/s10336-006-0121-1 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10336-006-0121-1 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Wilk Tomasz Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland aut NATIONALLICENCE 700 1- Dubiec Anna Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland aut NATIONALLICENCE 700 1- Cichoń Mariusz Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland aut NATIONALLICENCE 773 0- Journal of Ornithology Springer-Verlag 148/2(2007-04-01), 199-205 0021-8375 148:2<199 2007 148 10336 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer