State-dependent foraging rules for social animals in selfish herds
Authored by SA Rands, RA Pettifor, JM Rowcliffe, G Cowlishaw
Date Published: 2004
DOI: 10.1098/rspb.2004.2906
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Abstract
Many animals gain benefits from living in groups, such as a dilution in
predation risk when they are closely aggregated (referred to as the
`selfish herd'). Game theory has been used to predict many properties of
groups (such as the expected group size), but little is known about the
proximate mechanisms by which animals achieve these predicted
properties. We explore a possible proximate mechanism using a spatially
explicit, individual-based model, where individuals can choose to rest
or forage on the basis of a rule-of-thumb that is dependent upon both
their energetic reserves and the presence and actions of neighbours. The
resulting behaviour and energetic reserves of individuals, and the
resulting group sizes, are shown to be affected both by the ability of
the forager to detect conspecifics and areas of the environment suitable
for foraging, and by the distribution of energy in the environment. The
model also demonstrates that if animals are able to choose (based upon
their energetic reserves) between selecting the best foraging sites
available and moving towards their neighbours for safety, then this also
has significant effects upon individuals and group sizes. The
implications of the proposed rule-of-thumb are discussed.
Tags
behavior
models
geometry
Predation risk
Search
Strategies
Group-size
Winter
Small birds