Abstract
Group feeding animals experience a number of competitive foraging costs that may result in a lowered feeding rate. It is important to distinguish between reductions in feeding rates that are caused by reduced food availability and physical interactions among foragers from those caused by the mere presence of foraging companions that may be self-imposed in order to obtain some benefit of group membership. Starlings (Sturnus vulgaris) reduce their feeding rates when in the company of simulated competitors located in an adjacent cage that cannot affect the food availability or interact with the forager. In the present study, we investigate whether the presence of simulated competitors in another species of passerine, nutmeg mannikins (Lonchura punctulata), can result in self-imposed reductions in feeding rates. When feeding in the company of simulated competitors, mannikins spent more non-foraging time near them, fed more slowly, reduced travel times between patches, reduced their scanning time and pecked more slowly. These results provide evidence that simulated competitors induce a reduction in pecking rate: behavioural interference. These self-imposed responses to competitors may have resulted from attempts to remain close to the non-feeding companions. Such self-imposed reductions in feeding rates may be a widespread yet generally unrecognised foraging cost to group feeding individuals.
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Acknowledgements
This research was supported by a Natural Sciences and Engineering Research Council of Canada Research Grant to L-A.G. S.G. received additional financial support through teaching assistantships granted by the Department of Biology of Concordia University. We thank Ron Moen, Jim Grant, Paul Albert and Bill Vickery as well as members of the Groupe de discussion en écologie comportementale de l’UQÀM for commenting on an earlier version of the MS. The experiment was conducted following the guidelines of the Canadian Council for Animal Care and was approved by Concordia University Animal Care Committee.
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Gauvin, S., Giraldeau, LA. Nutmeg mannikins (Lonchura punctulata) reduce their feeding rates in response to simulated competition. Oecologia 139, 150–156 (2004). https://doi.org/10.1007/s00442-003-1482-2
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DOI: https://doi.org/10.1007/s00442-003-1482-2