Premium
Late‐breeding Great Cormorants P halacrocorax carbo sinensis produce fewer young of the more vulnerable sex
Author(s) -
WojczulanisJakubas Katarzyna,
Minias Piotr,
Kaczmarek Krzysztof,
Janiszewski Tomasz
Publication year - 2013
Publication title -
ibis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.933
H-Index - 80
eISSN - 1474-919X
pISSN - 0019-1019
DOI - 10.1111/ibi.12061
Subject(s) - brood , offspring , biology , sex ratio , hatching , seasonal breeder , cormorant , zoology , ecology , demography , predation , population , pregnancy , genetics , sociology
We examined the brood sex ratio and offspring body mass in relation to the timing of breeding and brood size in the Great Cormorant P halacrocorax carbo sinensis . The brood sex ratio was not related to brood size but it was significantly related to the hatching date, with a decreasing proportion of males in the brood in the course of the season. Male chicks had significantly lower body mass if they hatched later in the season, whereas there was no such relationship for female offspring. Assuming that environmental conditions deteriorate with progress of the breeding season, and male offspring may be more vulnerable to poor environmental conditions, the observed decline in the proportion of male offspring late in the season may be adaptive.