The evolution of brood reduction by siblicide in birds

Godfray, H. Charles J.; Harper, Alan

doi:10.1016/s0022-5193(05)80122-5

Cited by 29 publications

(17 citation statements)

References 25 publications

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“…Infanticide has been reported in white stork as a drastic means of brood reduction ( Schüz 1984; Tortosa & Redondo 1992), but we did not observe it in this study. Siblicide is another possible direct means of brood reduction ( Godfray & Harper 1990; Rodriguez‐Girones 1996): here, we suggest that individual differences in behaviour of the chicks may indirectly determine the survival of their siblings.…”

Section: High Plasma Testosterone Concentrations Are a Hormonal Meansmentioning

confidence: 77%

Brood Reduction in White Storks Mediated through Asymmetries in Plasma Testosterone Concentrations in Chicks

1999

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We hypothesized that increasing chick plasma testosterone concentrations, transmitted from the mothers via their eggs, enhances survival of their offspring and that the fitness of the young, depending on the maternal hormones, is influenced by parental quality. To test our hypotheses we distinguished the broods of white storks Ciconia ciconia L. where chicks died and those where all chicks survived. We analysed the plasma testosterone concentrations in the chicks, the ability of the chicks to be first to receive food and the mass of chicks before fledging in relation to their hatching order and recorded the body mass of parents and food mass delivered by them. Female storks used the asymmetries in testosterone concentrations within a brood to control brood size and adjusted the number of young hatched to match the parental ability to rear offspring. Females of poor condition altered the testosterone concentrations to produce large differences between the chicks: The first‐hatched chicks, which had high plasma testosterone levels, responded faster to the feeding parent and received more food than did their younger siblings. One or two later‐hatched chicks, which had lower testosterone levels, died in these broods. Females in good condition produced small differences in testosterone concentrations between the chicks and all chicks survived in their brood. Chicks that were raised by the females of poor condition in reduced broods were heavier than chicks that were raised by females of good condition in broods where all chicks survived. We suggest that the control of brood size by testosterone concentration, transmitted by the mother to the chicks, is a hormonal means of condition‐dependent reproductive strategy in the white stork.

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Section: High Plasma Testosterone Concentrations Are a Hormonal Meansmentioning

confidence: 77%

Brood Reduction in White Storks Mediated through Asymmetries in Plasma Testosterone Concentrations in Chicks

1999

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“…However, when brood reduction occurs, the benefit in fledging condition accrued by each surviving chick may outweigh any gain in inclusive fitness to that chick had the brood not been reduced. Consequently, parents and older nestlings are expected to disagree about whether brood reduction should occur, at least when food is plentiful (O'Connor 1978;Parker and Mock 1987;Godfray and Harper 1990;Clutton-Brock 1991). Our finding that the extent of jockeying for position is correlated with the occurrence of brood reduction is consistent with the idea that sibling competition affects the outcome of this conflict of interests.…”

Section: Discussionmentioning

confidence: 99%

American robin nestlings compete by jockeying for position

McRae

Montgomerie

1993

Behav Ecol Sociobiol

131

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We investigated whether nestling American robins (Turdus migratorius) were capable of influencing food distribution in their nests by perceiving that certain sectors of the nest received a relatively high proportion of feedings and positioning themselves accordingly.Feeding observations were obtained from videotape recordings taken at different stages of the nestling period. Parents generally arrived at a predictable location on the nest rim and allocated proportionally more food to nestlings in the central position. The degree of nestling movement was significantly positively correlated with variation in the predictability of parental arrival locations on the nest rim. Furthermore, nestlings moved more in broods suffering brood reduction. This suggests that when competition for food is intense and the location of parental arrival is predictable, nestlings respond by jockeying for access to the most favorable (i.e., central) position in the nest. We conclude that jockeying for position by nestlings can influence the pattern of food allocation by parents, and that hungry nestlings can improve their competitive standing against nestmates by moving to positions where parents are more likely to feed them.

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“…Dominants that selfishly consume the largest share of food provided by parents can benefit from increased growth and survival, whereas subordinates may suffer reduced growth and survival [3,4]. Theoretically, siblings should avoid escalated conflicts by adhering to dominance conventions based on differences in resource-holding power, unless the benefits outweigh their costs [5,6]. Competitive asymmetries may be conferred by birth order in avian species with marked asynchronous hatching [7,8], or by intrinsic factors such as fighting ability [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Sibling rivalry: training effects, emergence of dominance and incomplete control

et al. 2012

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Within-brood or -litter dominance provides fitness-related benefits if dominant siblings selfishly skew access to food provided by parents in their favour. Models of facultative siblicide assume that dominants exert complete control over their subordinate sibling's access to food and that control is maintained, irrespective of the subordinate's hunger level. By contrast, a recent functional hypothesis suggests that subordinates should contest access to food when the cost of not doing so is high. Here, we show that within spotted hyena (Crocuta crocuta) twin litters, dominants most effectively skew access to maternal milk in their favour when their aggression prompts a highly submissive response. When hungry, subordinates were less submissive in response to aggression, thereby decreasing lost suckling time and increasing suckling time lost by dominants. In a species where adult females socially dominate adult males, juvenile females were more often dominant than males in mixed-sex litters, and subordinate sisters used more effective counter-tactics against dominant brothers than subordinate brothers against dominant sisters. Our results provide, to our knowledge, the first evidence in a mammal that dominant offspring in twin litters do not exert complete control over their sibling's access to resources (milk), and that sibling dominance relationships are influenced by sibling sex and training effects.

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The evolution of brood reduction by siblicide in birds

Cited by 29 publications

References 25 publications

Brood Reduction in White Storks Mediated through Asymmetries in Plasma Testosterone Concentrations in Chicks

Brood Reduction in White Storks Mediated through Asymmetries in Plasma Testosterone Concentrations in Chicks

American robin nestlings compete by jockeying for position

Sibling rivalry: training effects, emergence of dominance and incomplete control

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