Sibling competition and siblicide in asynchronously-hatching broods of the cattle egret Bubulcus ibis
1985; Elsevier BV; Volume: 33; Issue: 4 Linguagem: Inglês
10.1016/s0003-3472(85)80183-4
ISSN1095-8282
Autores Tópico(s)Avian ecology and behavior
ResumoFeeding behaviour and sibling competition were observed in nine families of the cattle egret (Bubulcus ibis) from blinds during 1359 nest-h throughout the nestling period. During days 0–19, size differences among siblings were clear; begging behaviour of chicks changed with time. At least one parent always attended the nest. Food boluses regurgitated early within a feeding period were received by senior chicks more often than by juniors. When any two siblings begged for food at the same time, the elder and younger received the first bolus on 65% and 35% of occasions respectively. Between days 20 and 39, the frequency of begging reached a peak. Begging behaviour became intense and stereotyped. The number of boluses received per begging declined rapidly, especially for junior chicks. In large broods, the success rate of begging was lower and fights occurred among siblings, especially among juniors. Out of 256 dyadic fights, the elder sibling won 85, lost one, and tied 171. The youngest chick died in two broods, apparently as the result of these fights (siblicide). No parents interfered in fights among their offspring. After day 40, the frequency of begging decreased gradually and ceased by day 80, No chicks died in the last period, although the frequency of fights in all large broods remained high.
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