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ABSTRACT Biparental care is common in socially monogamous avian species, but both partners may seek extra‐pair copulations (EPCs). The relative costs and benefits of EPCs between the sexes are likely complex, yet the implications of EPCs for parental care behavior have been examined predominantly in males. Not only could females benefit from EPCs, but females would have additional information about the likelihood of extra‐pair young (EPY) in their nest not available to their partners, which likely influences female behavior. We examined how the presence and abundance of EPY in a nest affect parental behavior in a socially monogamous songbird, song sparrows (Melospiza melodia). We predicted that females who mated outside the social pair would invest more in a clutch with a higher probability of EPY. We monitored nest visitation rates by male and female social partners as a proxy for parental investment and quantified extra‐pair paternity in 45 nests. Maternal visitation rates were higher in nests with EPY compared to nests without, while males did not adjust their investment in relation to the presence of EPY. These findings support our prediction that females who participated in EPC would invest more in the resulting offspring.
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Female space use correlates with extra-pair mating in barn swallow replacement clutches
Abstract Extra-pair mating is common in avian species and can modulate the strength of sexual selection. Mate searching behavior of female birds may be an important predictor of mating opportunities and extra-pair mating, yet important knowledge is lacking as we have little data on fine-scale movement of females during the peak fertilization period. Accordingly, much is still unknown about whether and how female phenotypes contribute to extra-pair mating. Here, we examined how female space use and female plumage color are associated with extra-pair mating outcomes in wild barn swallows (Hirundo rustica erythrogaster). We tracked 10 females breeding in Colorado, USA with GPS backpack tags for two hours each morning during their fertile period following an experimental nest failure. We then used low-coverage whole-genome sequencing to determine offspring paternity and to quantify extra-pair mating in the removed clutch and the replacement clutch. Plumage and movement did not correlate with changes in paternity between successive clutches, but movement did correlate with paternity in the replacement clutch. Females that spent more time away from the nest had a higher proportion and number of extra-pair offspring in the clutch laid immediately after the tracking period. These results suggest that differences in female space use contribute to differences in extra-pair fertilizations. In contrast to the historic emphasis on male traits, our study highlights female movement behavior as an important variable associated with mating outcomes in natural populations.
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- PAR ID:
- 10571937
- Publisher / Repository:
- Springer Science + Business Media
- Date Published:
- Journal Name:
- Behavioral Ecology and Sociobiology
- Volume:
- 79
- Issue:
- 2
- ISSN:
- 0340-5443
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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