Some aspects of feeding and foraging behaviour of three corvids in Newfoundland

Maccarone, Alan David (1981) Some aspects of feeding and foraging behaviour of three corvids in Newfoundland. Masters thesis, Memorial University of Newfoundland.

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    Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.
    (Original Version)

Abstract

Research began with a study of nest predation by a pair of Common Ravens in a colony of cliff-nesting kittiwakes during summer, 1979. Patrols by single ravens were twice as successful as when both birds hunted together. Kittiwake anti-predator defense was important in reducing predation. Results of a cost/benefit analysis suggest that the ravens obtained sufficient prey to meet daily energy requirements. -- A series of feeding and foraging experiments, designed to test several basic assumptions of Optimal Foraging Theory, was carried out between September 1979 and June 1980, using freeliving Gray Jays and Common Crows and artificial prey populations. Both species became more discriminating in bait selection when relative and absolute abundances of profitable baits were increased. When populations of artificial baits consisted of two and three different types, jays differentially selected bait types on the basis of net energy value. Individuals differed in food preference and foraging efficiency. The possible influences of social status and prior experience are discussed. -- Three experiments were designed to induce switching of prey preferences among the jays by decreasing the profitability of a preferred food. Manipulations that produced increases in handling, search, and recognition times caused the jays to switch to an alternate bait, but they were reluctant to take a second alternate that was low in net energy value. Many of these data support current models of Optimal Foraging Theory. -- In a final experiment, a Great Horned Owl decoy was used to disrupt the feeding behaviour of a family of Gray Jays. Differences were found between juveniles and adults in anti-predator behaviour and food preference, juveniles being less cautious in the presence of the decoy and less discriminating in bait preference. Possible reasons for these differences are discussed.

Item Type: Thesis (Masters)
URI: http://research.library.mun.ca/id/eprint/5824
Item ID: 5824
Additional Information: Bibliography: leaves 95-105.
Department(s): Humanities and Social Sciences, Faculty of > Psychology
Science, Faculty of > Psychology
Date: 1981
Date Type: Submission
Geographic Location: Canada--Newfoundland and Labrador--Baccalieu Island
Library of Congress Subject Heading: Predation (Biology); Ravens--Behavior; Birds of prey--Newfoundland and Labrador--Baccalieu Island

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