EXTRA-PAIR COPULATIONS OF GRAY HERONS NESTING AT HIGH-DENSITIES

Authors
Citation
C. Ramo, EXTRA-PAIR COPULATIONS OF GRAY HERONS NESTING AT HIGH-DENSITIES, Ardea, 81(2), 1993, pp. 115-120
Citations number
17
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Ornithology
Journal title
ArdeaACNP
ISSN journal
0373-2266
Volume
81
Issue
2
Year of publication
1993
Pages
115 - 120
Database
ISI
SICI code
0373-2266(1993)81:2<115:ECOGHN>2.0.ZU;2-E
Abstract
The copulatory behaviour of Grey Heron Ardea cinerea was observed in a colony in Donana (SW Spain) during two years. A total of 262 pair cop ulation attempts (PCAs) and 39 extra-pair copulation attempts (EPCAs) (12.9% of all copulation attempts) were observed among 31 focal pairs. 84% of PCAs and 50% of EPCAs resulted in cloacal contact. Eleven male s (35%) and 19 (61%) females were involved in EPCAs. There was a corre lation between the time that female spent alone on the nest and the oc currence of EPCAs during the presumed fertile period of the female. Th e incidence of EPCAs observed at Donana was greater than reported for the species in other localities, and could be explained by more opport unities for promiscuous behaviour at high densities. Data provided by this study support the conclusion that mate guarding and PC frequency are mechanisms of paternity defense under the sperm competition hypoth esis.