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Brood sex ratios, female harem status and resources for nestling provisioning in the great reed warbler (Acrocephalus arundinaceus)

Westerdahl, Helena LU ; Bensch, Staffan LU ; Hansson, Bengt LU ; Hasselquist, Dennis LU and von Schantz, Torbjörn LU (2000) In Behavioral Ecology and Sociobiology 47(5). p.312-318
Abstract
The theory of parental investment and brood sex ratio manipulation predicts that parents should invest in the more costly sex during conditions when resources are abundant. In the polygynous great reed warbler, Acrocephalus arundinaceus. females of primary harem status have more resources for nestling provisioning than secondary females, because polygynous males predominantly assist the primary female whereas the secondary female has to feed her young alone. Sons weigh significantly more than daughters, and are hence likely to be the more costly sex. In the present study, we measured the brood sex ratio when the chicks were 9 days old, i.e. the fledging sex ratio. As expected from theory, we found that female great reed warblers of primary... (More)
The theory of parental investment and brood sex ratio manipulation predicts that parents should invest in the more costly sex during conditions when resources are abundant. In the polygynous great reed warbler, Acrocephalus arundinaceus. females of primary harem status have more resources for nestling provisioning than secondary females, because polygynous males predominantly assist the primary female whereas the secondary female has to feed her young alone. Sons weigh significantly more than daughters, and are hence likely to be the more costly sex. In the present study, we measured the brood sex ratio when the chicks were 9 days old, i.e. the fledging sex ratio. As expected from theory, we found that female great reed warblers of primary status had a higher proportion of sons in their broods than females of lower (secondary) harem status. This pattern is in accordance with the results from two other species of marsh-nesting polygynous birds, the oriental reed warbler, Acrocephalus orientalis, and the yellow-headed blackbird Xanthocephalus xanthocephalus. As in the oriental reed warbler, we found that great reed warbler males increased their share of parental care as the proportion of sons in the brood increased. We did not find any difference in fitness of sons and daughters raised in primary and secondary nests. The occurrence of adaptive sex ratio manipulations in birds has been questioned, and it is therefore important that three studies of polygynous bird species, including our own, have demonstrated the same pattern of a male-biased offspring sex ratio in primary compared with secondary nests. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Behavioral Ecology and Sociobiology
volume
47
issue
5
pages
312 - 318
publisher
Springer
external identifiers
  • scopus:0034109963
ISSN
1432-0762
DOI
10.1007/s002650050671
project
Breeding ecology of great reed warblers
Wild great reed warblers
language
English
LU publication?
yes
id
53be30fa-5916-46aa-a5dd-9d5f985be2a1 (old id 146029)
date added to LUP
2007-06-26 12:42:27
date last changed
2017-08-27 04:07:44
@article{53be30fa-5916-46aa-a5dd-9d5f985be2a1,
  abstract     = {The theory of parental investment and brood sex ratio manipulation predicts that parents should invest in the more costly sex during conditions when resources are abundant. In the polygynous great reed warbler, Acrocephalus arundinaceus. females of primary harem status have more resources for nestling provisioning than secondary females, because polygynous males predominantly assist the primary female whereas the secondary female has to feed her young alone. Sons weigh significantly more than daughters, and are hence likely to be the more costly sex. In the present study, we measured the brood sex ratio when the chicks were 9 days old, i.e. the fledging sex ratio. As expected from theory, we found that female great reed warblers of primary status had a higher proportion of sons in their broods than females of lower (secondary) harem status. This pattern is in accordance with the results from two other species of marsh-nesting polygynous birds, the oriental reed warbler, Acrocephalus orientalis, and the yellow-headed blackbird Xanthocephalus xanthocephalus. As in the oriental reed warbler, we found that great reed warbler males increased their share of parental care as the proportion of sons in the brood increased. We did not find any difference in fitness of sons and daughters raised in primary and secondary nests. The occurrence of adaptive sex ratio manipulations in birds has been questioned, and it is therefore important that three studies of polygynous bird species, including our own, have demonstrated the same pattern of a male-biased offspring sex ratio in primary compared with secondary nests.},
  author       = {Westerdahl, Helena and Bensch, Staffan and Hansson, Bengt and Hasselquist, Dennis and von Schantz, Torbjörn},
  issn         = {1432-0762},
  language     = {eng},
  number       = {5},
  pages        = {312--318},
  publisher    = {Springer},
  series       = {Behavioral Ecology and Sociobiology},
  title        = {Brood sex ratios, female harem status and resources for nestling provisioning in the great reed warbler (Acrocephalus arundinaceus)},
  url          = {http://dx.doi.org/10.1007/s002650050671},
  volume       = {47},
  year         = {2000},
}