AVIS-IBIS

Birds of Indian Subcontinent

Time Allocation between Territories and Flocks and Owner-Satellite Conflict in Foraging Pied Wagtails, Motacilla alba

Publication Type:Journal Article
Year of Publication:1983
Authors:Davies, NB, Houston, AI
Journal:Journal of Animal Ecology
Volume:52
Issue:2
Date Published:1983
ISBN Number:00218790
Keywords:Motacilla, Motacilla alba, Motacillidae
Abstract:(1) On Port Meadow, near Oxford, some pied wagtails defended winter feeding territories along a river while others fed in flocks around flooded pools nearby. (2) The territories provided a renewing food supply (insects) and an owner's feeding rate depended on the time allowed for resource renewal between visits to a stretch. Around the pools there were large accumulations of insects which provided a relatively constant feeding rate on any given day. (3) Territory owners often spent the day moving repeatedly back and forth between their territories and the flocks. (4) We reject a model which predicts the optimal time allocation between territory and flock to maximize an owner's daily feeding rate. Owners still spent time on territory even when, in the short term, they would have had a greater feeding rate by spending the whole day with the flock. (5) The data provide some support for a model which assumes that the territories are defended as a long-term investment and that the periodic visits to the territory are to prevent intruders, which settle in the owner's absence, from feeding at a profitable rate and hence persisting in their trespass. However, the model does not predict the owner's time budget in detail. (6) Owners sometimes shared their territories with a satellite. Unlike owners, satellites only spent time on a territory when their feeding rate was greater there than in the flock. Conflicts of interest can arise where it pays an owner to share its territory, but a satellite does better by staying with the flock.
URL:http://www.jstor.org/stable/4576
Short Title:Journal of Animal Ecology
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