Under what conditions is brood reduction effective?

SummaryFrom 2000–2008 we used transmitting video cameras to document the breeding biology of the endangered Bearded Vulture in the Pyrenees (NE Spain), focusing the study on sibling aggression. Our goals were to study the feasibility of rescuing second-hatched chicks for conservation purposes in this species that shows obligate brood reduction. The age at which the second chick died varied between 4 and 9 days (n= 5). Prey items delivered per hour were not related to the survival time of the second chick or the aggressiveness of the first-hatched chick towards their sibling. Although sibling aggression generally began on day 1 after hatching, in two nests supplemented with food, aggression was delayed until the second and third day after hatching and the second chick survived for nine days. Our results on the death of the second chick and the test involving the rescuing of a second-hatched chick aged five days, suggest that the recommended age for intervention should be between 3 and 6 days, with 4–5 days probably being the optimal age for the rescue.

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Ectoparasitic blow flies (Protocalliphora sp.) and nestling Eastern Bluebirds (Sialia sialis): direct effects and compensatory strategies

Canadian Journal of Zoology ◽

10.1139/z06-079 ◽

2006 ◽

Vol 84 (7) ◽

pp. 921-930 ◽

Cited By ~ 25

Author(s):

Kristina Hannam

Keyword(s):

Brood Reduction ◽

Direct Effects ◽

Negative Effects ◽

Compensatory Strategies ◽

Blow Flies ◽

Sialia Sialis ◽

Eastern Bluebird ◽

Eastern Bluebirds ◽

Nestling Period ◽

Host Parasite

Variation in environmental factors such as parasitism can have direct effects on an organism’s fitness. Because parasites draw resources directly from their hosts, they are expected to have negative effects; however, several nestling host – parasite systems show no evidence of direct effects. Absence of direct effects may be explained by compensation strategies used by parents or nestlings themselves. In this study evidence for both direct effects and compensatory strategies in a blow fly (genus Protocalliphora Hough, 1899) – Eastern Bluebird (Sialia sialis (L., 1758)) system were examined. Nestlings showed no direct effects of blow flies on survival and on size at fledging; however, parasitized broods were significantly anemic. There was no evidence for compensation by parents in the form of brood reduction and there was no support for compensation by nestlings via a hierarchy of tissue preservation. Nestlings did compensate for parasitism by accelerating growth at the end of the nestling period and delaying fledging.

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TEMPORAL PATTERNS OF PARENTAL RESOURCE DISTRIBUTION IN THE RED-NECKED GREBE: EQUALIZING THE SHARE OF THE SURVIVORS

Behaviour ◽

10.1163/156853901317367636 ◽

2001 ◽

Vol 138 (11-12) ◽

pp. 1355-1370 ◽

Cited By ~ 6

Author(s):

Janusz Kloskowski

Keyword(s):

Resource Allocation ◽

Dominance Hierarchy ◽

Food Distribution ◽

Brood Reduction ◽

Male And Female ◽

Investment Allocation ◽

Parental Aggression ◽

Competition For Food ◽

Podiceps Grisegena ◽

Over Time

AbstractFood distribution within brood and parental aggression to chicks were studied in the asynchronously hatching red-necked grebe Podiceps grisegena throughout the whole period of parental care. When carrying young - during the first two weeks after hatching - parents did not interfere in sibling competition for food. The proportions of food received by each brood member reflected the dominance hierarchy. After this period, parents showed aggression to offspring, especially to the older chicks and the within-brood hierarchy of received food was gradually reversed. Junior chicks were also longer cared for than their older sibling. Male and female parents did not differ in the food apportionment among differentrank chicks. It is suggested that red-necked grebe parents change the within-brood investment allocation over time. In the first weeks after hatching, they allow biased food distribution and in consequence even brood reduction. Later, they intervene in resource allocation and attempt to equalize the post-fledging survival of all chicks. Parental aggression appears to be a means both for counteracting the competitive advantage of older sibs and for forcing the chicks to independence.

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Adaptive sex allocation by brood reduction in antechinuses

Behavioral Ecology and Sociobiology ◽

10.1007/bf00167060 ◽

1994 ◽

Vol 35 (1) ◽

pp. 53-62 ◽

Cited By ~ 25

Author(s):

Andrew Cockburn

Keyword(s):

Sex Allocation ◽

Brood Reduction

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Heavy and persistent rainfall leads to brood reduction and nest failure in a passerine bird

Journal of Avian Biology ◽

10.1111/jav.02418 ◽

2020 ◽

Vol 51 (7) ◽

Author(s):

Eva Maria Schöll ◽

Sabine Marlene Hille

Keyword(s):

Passerine Bird ◽

Brood Reduction ◽

Nest Failure

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Context and Frequency of Infanticide in Communally Breeding Guira Cuckoos

The Condor ◽

10.1093/condor/103.1.170 ◽

2001 ◽

Vol 103 (1) ◽

pp. 170-175 ◽

Cited By ~ 3

Author(s):

Regina H. F. Macedo ◽

Mariana Cariello ◽

Laura Muniz

Keyword(s):

Egg Laying ◽

Brood Reduction ◽

Insect Abundance ◽

Central Brazil ◽

Asynchronous Hatching ◽

Almost All

Abstract We studied the context of brood reduction through infanticide by communally breeding Guira Cuckoos (Guira guira) in central Brazil. During seven reproductive seasons, we monitored 142 nests from egg laying until fledging. Almost all nests (97%) lost eggs through ejection, and chick deaths occurred in 72% of all nests with hatchlings. There was evidence for infanticide in 38% of the nests that exhibited some mortality. We compared egg and chick mortality in the early part of the season with the later part, when insect abundance declines, but found no significant differences. Less than one-third of all nests monitored showed asynchronous hatching of eggs, and in those that did, chick death was not in reverse hatch order. Although there are several plausible explanations for infanticide, we highlight one likely candidate, which is its interpretation as a sexually selected trait where individuals gain reproductive benefits by provoking the group's nesting failure.

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