Female-biased sex allocation in peregrine falcons and other raptors

Olsen, Penny; Cockburn, Andrew

doi:10.1007/bf00164123

Cited by 89 publications

(73 citation statements)

References 32 publications

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“…Treecreepers lack clear secondary sexual traits that could serve as ornaments and are visible to human beings and all the traits of the male parents measured were unrelated to any variations in the sex ratio. It is thought that sex ratio can also change over the breeding season (Dijkstra et al 1990;Bednarz & Hayden 1991;Olsen & Cockburn 1991;Zijlstra et al 1992;Daan et al 1996); however, in our data such a relationship was not found. In summary, we found that habitat quality as measured by habitat structure was associated with a high level of variation in the primary brood sex ratio.…”

Section: Discussioncontrasting

confidence: 91%

Forest fragmentation is associated with primary brood sex ratio in the treecreeper (Certhia familiaris)

Suorsa

Helle

Huhta

et al. 2003

Proc. R. Soc. Lond. B

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We studied the primary brood sex ratio of an old-growth forest passerine, the Eurasian treecreeper (Certhia familiaris), along a gradient of forest fragmentation. We found evidence that male nestlings were more costly to produce, since they suffered twofold higher nestling mortality and were larger in body size than females. Furthermore, the proportion of males in the brood was positively associated with the provisioning rate and the amount of food delivered to the nestlings. During the first broods, a high edge density and a high proportion of pine forests around the nests were related to a decreased production of males. The densities of spiders, the main food of the treecreeper, were 38% higher on spruce trunks than on pine trunks. This suggests that pine-dominated territories with female-biased broods may have contained less food during the first broods. The observation was further supported by the fact that the feeding frequencies were lower in territories with high proportions of pines. In the second broods, territories with a high forest patch density produced female-biased broods, whereas high-quality territories with a large amount of deciduous trees and mixed forests produced male-biased broods. Our results suggest that habitat quality as measured by habitat characteristics is associated with sex allocation in free-living birds.

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Section: Discussioncontrasting

confidence: 91%

Forest fragmentation is associated with primary brood sex ratio in the treecreeper (Certhia familiaris)

Suorsa

Helle

Huhta

et al. 2003

Proc. R. Soc. Lond. B

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“…The long-term and inclusive fitness effects of the BSR are still unknown and experimental work in this area is urgently required (see also Komdeur & Pen 2002). Nager et al 1999;(31) Nishiumi 1998;(32) Nishiumi et al 1996;(33) Oddie 2000;(34) Olsen & Cockburn 1991;(35) Patterson et al 1980;(36) Sheldon et al 1997;(37) Sheldon et al 1999;(38) Smallwood & Smallwood 1998;(39) Svensson & Nilsson 1996;(40) Teather 1987;(41) Teather & Weatherhead 1988;(42) Tella et al 1996;(43) Torres & Drummond 1999;(44) Weatherhead 1983;(45) Weimerskirch et al 2000;(46) Westerdahl et al 1997;(47) Westerdahl et al 2000;(48) Wiebe & Bortolotti 1992;(49) Zijlstra et al 1992. ( †Theoretical studies.…”

Section: How To Investigate Adaptive Bsr Manipulation In Relation To mentioning

confidence: 99%

“…Nestlings of large sex out-compete small sex for parental care prediction: (i) a consistently small-sex biased primary sex ratio to compensate for their higher nestling mortality (ii) a bias in favour of nestlings of the large sex during favourable conditions, e.g. high parental and/or territory quality (Olsen & Cockburn 1991) (iii) broods with all chicks of same sex (Newton 1986;Olsen & Cockburn 1991;Heinsohn et al 1997 Emlen et al 1986) (b) groups with (several) helpers already present prediction:…”

Section: Bsr Manipulation Under Different Patterns Of Parental Carementioning

confidence: 99%

Parental care and adaptive brood sex ratio manipulation in birds

Hasselquist

Kempenaers

2002

Phil. Trans. R. Soc. Lond. B

168

128

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Under many circumstances, it might be adaptive for parents to bias the investment in offspring in relation to sex. Recently developed molecular techniques that allow sex determination of newly hatched offspring have caused a surge in studies of avian sex allocation. Whether females bias the primary brood sex ratio in relation to factors such as environmental and parental quality is debated. Progress is hampered because the mechanisms for primary sex ratio manipulation are unknown. Moreover, publication bias against nonsignificant results may distort our view of adaptive sex ratio manipulation. Despite this, there is recent experimental evidence for adaptive brood sex ratio manipulation in birds. Parental care is a particularly likely candidate to affect the brood sex ratio because it can have strong direct effects on the fitness of both parents and their offspring. We investigate and make predictions of factors that can be important for adaptive brood sex ratio manipulation under different patterns of parental care. We encourage correlational studies based on sufficiently large datasets to ensure high statistical power, studies identifying and experimentally altering factors with sex-differential fitness effects that may cause brood sex ratio skew, and studies that experimentally manipulate brood sex ratio and investigate fitness effects.

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“…of raptors have demonstrated biased sex allocation with respect to laying date (Dijkstra et al 1990;Olsen & Cockburn 1991;Zijlstra et al 1992;Daan et al 1996), laying sequences within broods (Bortolotti 1986;Edwards et al 1988;Bednarz & Hayden 1991;Leroux & Bretagnolle 1996) and maternal condition (Wiebe & Bortolotti 1992). Although these studies explained adaptive sex ratio manipulation at the individual level, they also reported overall male-biased sex ratios of nestlings or fledglings at the population level, with the except of one study (Dijkstra et al 1990).…”

Section: Other Important Investigationsmentioning

confidence: 99%

Sex Ratio among Fledglings of Blakiston's Fish Owls.

Hayashi

Nishida‐Umehara

2000

Japanese Journal of Ornithology

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The sex ratio of 137 fledglings, from 91 broods, of Blakiston's Fish Owls Ketupa blakistoni raised in Hokkaido, Japan, over the period 1985-99, was analyzed. The sex ratio of fledglings was significantly male-biased (81 males. and 56 females; P=0.04) although no significant difference was detected when it was compared to the expected value (50% males) for each brood size (one or two). Logistic regression analysis did not reveal any significant effects of the locations of breeding sites on the sex ratio of fledglings. Young male owls suffered higher mortality than females. It is suggested that the male-biased sex ratio at fledging is moderated toward parity during the post-fledging stage. Factors considered to attribute to the skewed sex ratio at fledging of Blakiston's Fish Owl were: sexual dimorphism, local resource competition (LRC) and demographic stochasticity resulting from the small population size. Sexual dimorphism suggested that the male-biased sex ratio of fledglings was qualitatively consistent with Fisher's theory. However, sexual dimorphism alone does not quantitatively explain the male-biased sex ratio in Blakiston's Fish Owls. Differential natal philopatry between the sexes suggests that LRC is occurring. The small population size of the Hokkaido population is considered to be the most alarming factor from a conservation point of view.

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Female-biased sex allocation in peregrine falcons and other raptors

Cited by 89 publications

References 32 publications

Forest fragmentation is associated with primary brood sex ratio in the treecreeper (Certhia familiaris)

Forest fragmentation is associated with primary brood sex ratio in the treecreeper (Certhia familiaris)

Parental care and adaptive brood sex ratio manipulation in birds

Sex Ratio among Fledglings of Blakiston's Fish Owls.

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