caa a22 4500 606193685 CHVBK 20210128100910.0 cr unu---uuuuu 210128e20150301xx s 000 0 eng 10.1007/s10682-014-9752-5 doi (NATIONALLICENCE)springer-10.1007/s10682-014-9752-5 Opposing selective pressures may act on the colony size in a waterbird species [Elektronische Daten] [Piotr Minias, Radosław Włodarczyk, Tomasz Janiszewski] In theory, larger colony size should be favoured by lower per-capita predation rates, whereas smaller colony size should be favoured by reduced parasitism, social stress and competition for food. We conducted an experimental cross-fostering of young between colonies of different size to test whether differences in fitness had an environmental or genetic basis. We induced formation of one large (ca. 100 breeding pairs) and three small (30-40 pairs) Common Tern Sterna hirundo colonies by providing different size patches of nesting area (floating rafts). The larger colony had about 30% higher reproductive success than the smaller colonies. However, offspring raised in the large colony were in poorer condition, which was indicated by the higher heterophil/lymphocyte ratios, lower hemoglobin concentrations in blood and slower growth rates, suggesting higher parasite loads or higher levels of social stress. By performing a cross-fostering experiment we confirmed that differences in chick condition were not inherited, but could be directly attributed to different rearing conditions experienced in the colonies of varying size. These results suggest that colony size in the Common Tern may be regulated by the opposing selective pressures (predation vs. parasitism/social stress). The Author(s), 2015 Coloniality nationallicence Common Tern nationallicence Cross-fostering nationallicence Haematology nationallicence Natural selection nationallicence Sterna hirundo nationallicence Minias Piotr Department of Teacher Training and Biodiversity Studies, University of Łódź, Banacha 1/3, 90-237, Lodz, Poland aut Włodarczyk Radosław Department of Teacher Training and Biodiversity Studies, University of Łódź, Banacha 1/3, 90-237, Lodz, Poland aut Janiszewski Tomasz Department of Teacher Training and Biodiversity Studies, University of Łódź, Banacha 1/3, 90-237, Lodz, Poland aut Evolutionary Ecology Springer International Publishing 29/2(2015-03-01), 283-297 0269-7653 29:2<283 2015 29 10682 https://doi.org/10.1007/s10682-014-9752-5 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s10682-014-9752-5 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Minias Piotr Department of Teacher Training and Biodiversity Studies, University of Łódź, Banacha 1/3, 90-237, Lodz, Poland aut NATIONALLICENCE 700 1- Włodarczyk Radosław Department of Teacher Training and Biodiversity Studies, University of Łódź, Banacha 1/3, 90-237, Lodz, Poland aut NATIONALLICENCE 700 1- Janiszewski Tomasz Department of Teacher Training and Biodiversity Studies, University of Łódź, Banacha 1/3, 90-237, Lodz, Poland aut NATIONALLICENCE 773 0- Evolutionary Ecology Springer International Publishing 29/2(2015-03-01), 283-297 0269-7653 29:2<283 2015 29 10682