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A sex-influenced flexible foraging strategy in a tropical seabird, the magnificent frigatebird

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journal contribution
posted on 2019-02-14, 00:00 authored by R E Austin, F De Pascalis, John ArnouldJohn Arnould, J Haakonsson, S C Votier, G Ebanks-Petrie, T Austin, G Morgan, G Bennett, J A Green
To successfully exploit resources, animals must be adapted to operate under phenotypic and environmental constraints. The strategies that predators use to locate prey are therefore diverse, particularly for breeding central-place foragers that must balance investment in reproduction and self-maintenance. Magnificent frigatebirds Fregata magnificens are tropical seabirds with intriguing morphology and feeding ecology, which display strikingly unequal levels of parental care (males deserting offspring months before females). These unusual traits can better help us understand the links between movement behaviour and breeding strategies in this poorly studied species. Using archival GPS, GPS-GSM loggers, bird-borne cameras and dietary data, we investigated the foraging ecology of chick-rearing magnificent frigatebirds from a breeding population in the Cayman Islands. This population engages in 2 main foraging strategies: (1) coastal trips over the continental shelf, where individuals target reef species and engage in kleptoparasitism, and (2) offshore trips during which birds feed on schooling pelagic prey. Differences in strategy use were partially linked to sex, with males (which invest less in offspring) roaming further from nests, and showing a higher propensity to forage offshore. Video data further indicated differences in social information use between strategies: foraging with conspecifics was more prevalent in coastal environments than pelagic. We suggest that observed variation in at-sea behaviour may partially be mediated by sex-based differences in parental roles, and/or size differences leading to intraspecific competition. Our study provides evidence of bimodal foraging and sheds new light on the importance of both pelagic and coastal feeding in this enigmatic species.

History

Journal

Marine ecology progress series

Volume

611

Pagination

203 - 214

Publisher

Inter-Research

Location

Oldendorf, Germany

ISSN

0171-8630

Language

eng

Publication classification

C Journal article; C1 Refereed article in a scholarly journal

Copyright notice

2019, The authors and the University of Liverpool