SEX-SPECIFIC GROWTH IN OSPREYS - THE ROLE OF SEXUAL SIZE DIMORPHISM

Citation
Cp. Schaadt et Dm. Bird, SEX-SPECIFIC GROWTH IN OSPREYS - THE ROLE OF SEXUAL SIZE DIMORPHISM, The Auk, 110(4), 1993, pp. 900-910
Citations number
47
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Ornithology
Journal title
ISSN journal
0004-8038
Volume
110
Issue
4
Year of publication
1993
Pages
900 - 910
Database
ISI
SICI code
0004-8038(1993)110:4<900:SGIO-T>2.0.ZU;2-D
Abstract
Sex-specific growth analyses were conducted for 20 male and 12 female Ospreys (Pandion haliaetus) in 19 broods in Nova Scotia, Canada during 1984-1986. The graphical methods of Ricklefs showed the logistic mode l to be most appropriate for mass increase with a growth-rate constant K of 0.18.days-1 for both sexes combined. The influence of sex on gro wth performance was also described using a reparameterized Richards mo del. Mass and tarsus length were the only variables to show well-defin ed asymptotes at fledging, although talon length, cranium width, and c ulmen length were within 10% of adult values. Males differed significa ntly from females in having lower asymptotes of mass and tarsus length , but did not differ in rate of growth. There was no difference in gro wth rates between individuals in broods of one, two or three nestlings , or within broods as a result of hatching-order asynchrony. Males and females showed no difference in age at time of feather emergence or i n length of nestling period. Thus, because there was no evidence for r apid growth in males in order to compete with larger females for food resources at nests, we suggest that sexual size dimorphism may be inde pendent of sibling competition in Ospreys.