Optimal clutch size inNycticorax nycticoraxandEgretta garzetta
作者:
Mauro Fasola,
Laura Pettiti,
期刊:
Bolletino di zoologia
(Taylor Available online 1993)
卷期:
Volume 60,
issue 4
页码: 385-388
ISSN:0373-4137
年代: 1993
DOI:10.1080/11250009309355843
出版商: Taylor & Francis Group
关键词: Egretta garzetta;Nycticorax nycticorax ‐Optimal clutch;Breeding success;Bird ecology
数据来源: Taylor
摘要:
The breeding success of night heron and little egret showed few and non‐systematic variations between two heronries over four years. The most frequent clutch sizes were 3 and 4 eggs, respectively. However, the highest productivity was attained by larger clutches: night heron nests with 4 hatched chicks and 2.6 survivors; little egret nests with 6 chicks and 4.6 survivors. These results confirm a pattern observed in other birds, namely that modal clutch size is lower than the most productive clutch size. Our results are consistent with the hypotheses that the discrepancies between actual and optimal clutch size is due either to a local abundance of food, or to the existence of individual optima.
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