Sibling Aggession and Brood Reduction in White-Tailed Eagles (Haliaeetus Albicilla)

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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WHITE-TAILED EAGLE (HALIAEETUS ALBICILLA) IN LITHUANIA: POPULATION NUMBERS AND TRENDS 1900-2007

Acta Zoologica Lituanica ◽

10.1080/13921657.2007.10512845 ◽

2007 ◽

Vol 17 (4) ◽

pp. 281-285 ◽

Cited By ~ 3

Author(s):

Deivis Dementavičius

Keyword(s):

Haliaeetus Albicilla ◽

Population Numbers

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