Laying date and laying sequence influence the sex ratio of crimson rosella broods

Krebs, E. A., Green, D. J., Double, M. C. and Griffiths, R. (2002) Laying date and laying sequence influence the sex ratio of crimson rosella broods. Behavioral Ecology And Sociobiology, 51 5: 447-454. doi:10.1007/s00265-002-0459-1

Author Krebs, E. A.
Green, D. J.
Double, M. C.
Griffiths, R.
Title Laying date and laying sequence influence the sex ratio of crimson rosella broods
Journal name Behavioral Ecology And Sociobiology   Check publisher's open access policy
ISSN 0340-5443
Publication date 2002
Sub-type Article (original research)
DOI 10.1007/s00265-002-0459-1
Volume 51
Issue 5
Start page 447
End page 454
Total pages 8
Place of publication Berlin
Publisher Springer-Verlag
Collection year 2002
Language eng
Subject C1
270706 Life Histories (incl. Population Ecology)
770703 Living resources (flora and fauna)
0502 Environmental Science and Management
0602 Ecology
Abstract We examine the patterns of sex allocation in crimson rosellas Platycercus elegans, a socially monogamous Australian parrot. Overall, 41.8% of nestlings were male, a significant female bias. However underlying this population-level bias were non-random patterns of sex allocation within broods. Broods produced early in the season were female-biased, but the proportion of males in a brood increased as the breeding season progressed. Female rosellas may obtain greater fitness benefits from early-fledging daughters than sons because daughters can breed as 1-year-olds whereas sons do not breed until they are at least 2 years old. Laying date and laying sequence also interacted to influence the sex ratio of eggs. The sex of early-laid eggs strongly followed the brood level pattern, whereas the sex of middle- and late-laid eggs did not change significantly as the season progressed. Nevertheless, late-laid eggs were very unlikely to be male at the end of the season. We argue these differing seasonal patterns reflect the relative costs and benefits to producing early-hatched males and females at different times of the season. Female rosellas appear to maximise the probability that daughters are able to breed early but to minimise competitive asymmetries within the brood. In particular, late-hatched male chicks are disadvantaged if their oldest sibling is male, explaining the dearth of broods containing late-hatched males at the end of the breeding season.
Keyword Behavioral Sciences
Hatch Order
Seasonal Patterns
Sex Allocation
Sibling Competition
Size Dimorphism
Food Allocation
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Agriculture and Food Sciences
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Citation counts: TR Web of Science Citation Count  Cited 42 times in Thomson Reuters Web of Science Article | Citations
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Created: Tue, 14 Aug 2007, 17:26:00 EST