Effects of Spacing and Synchrony on Breeding Success in the Great Frigatebird (Fregata minor)
1988; Oxford University Press; Volume: 105; Issue: 2 Linguagem: Inglês
10.2307/4087486
ISSN1938-4254
Autores Tópico(s)Animal Behavior and Reproduction
ResumoNearest-neighbor methods of spatial analysis confirmed that colonies of Great Frigatebirds (Fregata minor) on Aldabra Atoll were subdivided into clusters of up to 22 nests/cluster. Each cluster arose from a nucleus of advertising, unpaired males. Within a cluster, sites were spaced regularly at intervals of 0.5-1 m. Clusters differed in degree of synchrony of female settlement. Hatching success correlated positively with synchrony of female settlement. The interval between female settlement and laying date decreased as the season progressed. Hatching or fledging success was not significantly affected by date of laying. Breeding success (fledglings/egg) exceeded 50% in both seasons. Great Frigatebird males formed display clusters one month before females settled, competed for display sites within clusters, and preferred clusters that contained eight or more displaying males. Females settled more readily by males in the larger colony and, early in the season, preferred clusters that already contained nests. I suggest that usurpation of nests by unpaired males was a principal cause of nesting failure, and that synchronous female settlement within a cluster made the cluster less attractive to prospecting males than one that contained mostly advertising males. Selective mate choice by females appears to be the principal agent inducing spatial clustering by males.
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