Unified effects of aggregation reveal larger prey groups take longer to find

Ioannou, C.C., Bartumeus, F., Krause, J. and Ruxton, G.D. (2011) Unified effects of aggregation reveal larger prey groups take longer to find. Proceedings of the Royal Society of London Series B: Biological Sciences, 278(1720), pp. 2985-2990. (doi: 10.1098/rspb.2011.0003)

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Publisher's URL: http://dx.doi.org/10.1098/rspb.2011.0003

Abstract

Previous work has suggested that larger groups of prey are more conspicuous to predators. However, this ignores that prey populations are finite. As groups get larger they become fewer, hence the encounter rate between predator and prey decreases with prey aggregation. Here, we present a two-dimensional model based on visual angle to unify these encounter and conspicuousness effects of aggregation. With experimental support using three-spined sticklebacks (<i>Gasterosteus aculeatus L.</i>), searching for chironomid larvae, we demonstrate that the increase in visual angle with increasing group size is outweighed by its corresponding decrease as the groups become fewer and thus further away from the searching predator. The net effect is that prey are found with more difficulty when they aggregate, giving an additional anti-predatory benefit to group living rather than a cost.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Ruxton, Professor Graeme
Authors: Ioannou, C.C., Bartumeus, F., Krause, J., and Ruxton, G.D.
College/School:College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
Journal Name:Proceedings of the Royal Society of London Series B: Biological Sciences
ISSN:0962-8452

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