MORTALITY OF FLEDGLING FEMALES CAUSES MALE BIAS IN THE SEX RATIO OF RUFOUS VANGAS (SCHETBA RUFA) IN MADAGASCAR

The Rufous Vanga (Schetba rufa) is a cooperative breeder. Although young males typically remain in natal territories, yearling females do not remain, but disperse to breed for themselves. The male-biased sex ratio likely restricts independent reproduction by young males. We analyzed demographic data...

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Bibliographic Details
Published in:The Auk 2003-07, Vol.120 (3), p.700-705
Main Authors: Asai, Shigeki, Yamagishi, Satoshi, Eguchi, Kazuhiro
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal behavior
Animal reproduction
Animal, plant and microbial ecology
Animals
Autoecology
Aves
Aviculture
Biological and medical sciences
Bird nesting
Breeding
Breeding seasons
Chromosomes
Deoxyribonucleic acid
DNA
Female animals
Females
Fundamental and applied biological sciences. Psychology
Gender bias
Hatching
Male animals
Mortality
Ornithology
Sex ratio
Vertebrata
Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution
Yearlings
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Summary:The Rufous Vanga (Schetba rufa) is a cooperative breeder. Although young males typically remain in natal territories, yearling females do not remain, but disperse to breed for themselves. The male-biased sex ratio likely restricts independent reproduction by young males. We analyzed demographic data from a seven-year study of the Rufous Vanga in Madagascar to estimate the mortality for each sex. We also examined the sex ratio at fledging and at hatching, sexing nestlings with DNA analysis on sex chromosomes. Analyses indicated that the biased sex ratio was due to differential mortality of fledglings rather than the bias at birth. We suggest that the delayed dispersal improved survival of auxiliary males.
ISSN:0004-8038
1938-4254
2732-4613
DOI:10.1642/0004-8038(2003)120[0700:MOFFCM]2.0.CO;2