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Variation in food defence as a function of local ecological conditions in the Zenaida dove

Two populations of Barbados Zenaida dove (Zenaida aurita) have in previous work been found to use two radically different modes of feeding competition. The St. James (StJ) population is territorial; it competes aggressively with conspecifics but scramble competes with heterospecifics. The Deep Water Harbour (DWH) population forages nonaggressively in large homospecfic flocks. Earlier studies linking these social differences with differences in individual and social learning suggest that Z. aurita is ideal for testing predictions from Brown's (1964) theory of economic defendability. Firstly, the hypothesis that resource defence will increase as the spatial clumping and temporal predictability of a resource increases was tested at 6 sites at DWH with a randomized complete block design. Secondly, spatial distribution of food was manipulated at both DWH and StJ in an attempt to alter the mode of foraging competition at DWH from scramble to interference, and to elicit group-feeding in the otherwise territorial StJ doves. As predicted, rates of aggression per intruder were highest for those sites at DWH receiving a spatially clumped and temporally predictable food source. Unlike those at DWH, doves from StJ did not modify their mode of foraging competition in response to variations in spatial distribution, but rather as a consequence of increased resource density. Interference competition appears to be the default strategy for Zenaida doves, with birds switching to scramble competition when a threshold of resource density is reached, only to revert back to aggressive defence when the spatial clumping and temporal predictability of food increases.

Identiferoai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.21558
Date January 1998
CreatorsGoldberg, Joanna L.
ContributorsLefebvre, Louis (advisor)
PublisherMcGill University
Source SetsLibrary and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada
LanguageEnglish
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation
Formatapplication/pdf
CoverageMaster of Science (Department of Biology.)
RightsAll items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated.
Relationalephsysno: 001658878, proquestno: MQ50777, Theses scanned by UMI/ProQuest.

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