caa a22 4500 469098252 CHVBK 20180323133037.0 cr unu---uuuuu 170328e19920401xx s 000 0 eng 10.1007/BF00317807 doi (NATIONALLICENCE)springer-10.1007/BF00317807 Growth and sex ratio of nestlings in two species of crows: how important is hatching asynchrony? [Elektronische Daten] [Tore Slagsvold, Magne Husby, Jostein Sandvik] Summary: In experimental studies of avian hatching paterns offspring sex has been neglected. This may be a problem if nestling growth and mortality is sex biased, and if this bias is influenced by hatching spread. In a field study of two crow species, the magpie Pica pica and the hooded crow Corvus corone cornix, we manipulated hatching spread. Both species have asynchronous hatching, and adult males are larger than females by 12-14%. The sex ratios obtained from the different experimental groups on day 24 post-hatch (total sample n = 403) did not deviate significantly from unity, nor did the sex ratios obtained among young newly hatched in an incubator (total sample n = 305). Male and female offspring were of similar size at hatching but males were larger on day 24 post-hatch. Males seemed to be more costly to rear than females, judging by the 20% difference in the mean amounts of food found in the gizzards of the young on day 24 post-hatch. Dimorphism in body size did not seem to be influenced by degree of hatching spread. Asynchronous hatching did not seem to be needed to produce high quality offspring of the larger sex (i.e. males), nor did asynchronous hatching help to ensure equal parental investment in male and female progeny. One reason for the latter negative results may be that the size dimorphism of the two crow species studied were relatively small. Springer-Verlag, 1992 Sex ratio nationallicence Sexual dimorphism nationallicence Hatching asynchrony nationallicence Pica pica nationallicence Corvus corone nationallicence Slagsvold Tore Department of Biology, Division of Zoology, University of Oslo, Blindern, P.O. Box 1050, N-0316, Oslo 3, Norway aut Husby Magne Department of Zoology, University of Trondheim, N-7055, Dragvoll, Norway aut Sandvik Jostein Department of Zoology, University of Trondheim, N-7055, Dragvoll, Norway aut Oecologia Springer-Verlag 90/1(1992-04-01), 43-49 0029-8549 90:1<43 1992 90 442 https://doi.org/10.1007/BF00317807 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00317807 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Slagsvold Tore Department of Biology, Division of Zoology, University of Oslo, Blindern, P.O. Box 1050, N-0316, Oslo 3, Norway aut NATIONALLICENCE 700 1- Husby Magne Department of Zoology, University of Trondheim, N-7055, Dragvoll, Norway aut NATIONALLICENCE 700 1- Sandvik Jostein Department of Zoology, University of Trondheim, N-7055, Dragvoll, Norway aut NATIONALLICENCE 773 0- Oecologia Springer-Verlag 90/1(1992-04-01), 43-49 0029-8549 90:1<43 1992 90 442 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer