AVIS-IBIS

Birds of Indian Subcontinent

Reproductive Effort and Breeding Success in Relation to Age by the Rook Corvus frugilegus

Publication Type:Journal Article
Year of Publication:1983
Authors:Røskaft, E, Espmark, Y, Järvi, T
Journal:Ornis Scandinavica
Volume:14
Issue:3
Date Published:1983
ISBN Number:00305693
Keywords:Corvidae, Corvus, Corvus frugilegus, Trypanocorax frugilegus
Abstract:According to Williams' (1966) hypothesis, young Rooks should expend less energy in reproduction, per offspring produced, than old Rooks. As a test of this hypothesis we investigated the time budgets of both males and females, of breeding pairs and the share of the female in feeding the nestlings. Finally, we recorded any observed differences in the breeding ecology of old and young Rooks. The results differed from the above mentioned theory. The parental effort of young birds is greater than that of older birds. During the incubation period, the young males fed their mates more frequently, and were absent from the nest for longer periods, than the older males. However, we were unable to detect any differences in the breeding behaviour of old and young females, although those females mated to young males begged for food more frequently than did the females mated to old males. The young females also laid smaller clutches than the older females and were less successful in hatching out their eggs. Similarly, the young males were less successful in rearing the nestlings than were the old males.
URL:http://www.jstor.org/stable/3676148
Short Title:Ornis Scandinavica
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