Krijgsveld K L, Dijkstra C, Visser G H, Daan S
Zoological Laboratory, University of Groningen, Haren, The Netherlands.
Physiol Zool. 1998 Nov-Dec;71(6):693-702. doi: 10.1086/515983.
Food consumption was measured in six female and seven male hand-raised marsh harrier (Circus aeruginosus) nestlings. Females consumed on average 4,321 g and males consumed 3,571 g of food during the nestling stage from 0 to 36 d. Total consumption until 56 d was 6,960 g and 5,822 g for females and males, respectively. On the basis of Fisher's sex ratio theory, this food intake ratio of 0.46 (intake male/[intake male + female]) would explain the observed male-biased fledging sex ratio of 55% males in marsh harrier broods. Growth, gross energy intake, and metabolizable energy intake were measured, along with metabolism of the nestlings, enabling us to determine energy allocation. The assimilation quotient (Q = 0.72) did not differ systematically between the sexes. Differences in metabolic rates between males and females at 15 and 30 d of age were fully attributable to the difference in body mass. Sexual size dimorphism in marsh harriers (female body mass around 60 d of age is 1.28 times greater than male mass) did not fully explain the difference in food intake between male and female nestlings: an analysis of energy requirements for growth and body mass in 16 avian species shows that energy intake was less than proportional to the average body mass at release. The data presented in this study are in agreement with Fisher's theory of inverse proportionality between the sex-specific ratios of energy requirements for growth and of offspring numbers in the marsh harrier population.
对6只雌性和7只雄性人工饲养的白尾鹞（Circus aeruginosus）雏鸟的食物摄入量进行了测量。在0至36日龄的雏鸟阶段，雌性雏鸟平均消耗4321克食物，雄性雏鸟消耗3571克食物。直到56日龄时，雌性和雄性雏鸟的总消耗量分别为6960克和5822克。根据费舍尔性别比例理论，这种0.46的食物摄入量比例（雄性摄入量/[雄性摄入量+雌性摄入量]）可以解释在白尾鹞育雏中观察到的雄性偏多的出飞性别比例，即雄性占55%。对雏鸟的生长、总能量摄入、可代谢能量摄入以及新陈代谢进行了测量，这使我们能够确定能量分配情况。两性之间的同化系数（Q = 0.72）没有系统性差异。15日龄和30日龄时，雄性和雌性之间代谢率的差异完全归因于体重差异。白尾鹞的两性体型差异（约60日龄时雌性体重比雄性体重高1.28倍）并不能完全解释雄性和雌性雏鸟之间食物摄入量的差异：对16种鸟类生长和体重的能量需求分析表明，能量摄入与出飞时的平均体重并非成比例关系。本研究中呈现的数据与费舍尔关于白尾鹞种群中生长所需能量的性别特定比例与后代数量成反比的理论相符。
