Female Black-Capped Chickadees (Poecile atricapillus) Expand Foraging Both Temporally and Spatially to Mitigate Interference Competition.

Authors

Elène Haave-Audet, Kimberley J Mathot

Published in

Ecology and evolution. Volume 16. Issue 7. Pages e73972. Epub Jul 10, 2026.

Abstract

Group living provides many potential benefits but can also incur important costs via competition for access to resources. Even in the absence of resource depletion, interference competition can reduce access to resources, and interference competition is not expected to affect all group members equally. In groups with dominance hierarchies, dominant individuals have priority access to resources and are therefore expected to experience lower costs of interference competition compared to subordinate individuals. Here, we assessed the effect of manipulating the number of feeders available with ad libitum food, which we assumed would affect competition intensity, on total daily feeder visits in a marked population of 126 black-capped chickadees (Poecile atricapillus). As predicted, we found strong evidence of interference competition: reducing feeder availability by 50% reduced average per capita daily visits to feeders in our population by circa 50%. Because chickadee flocks exhibit linear dominance hierarchies, with males being dominant over females, and at least in some populations, adults being dominant over immatures, we also investigated whether there was evidence for sex- and/or age-related differences in the strength of interference competition. We found that reductions in total daily feeder visits under lower manipulated food availability were similar for all age-sex categories, suggesting that females and immatures did not experience higher interference competition despite their subordinate status relative to males and adults. Post hoc analyses revealed that adult females expanded their foraging area, while immature females increased both the length of the foraging window and foraging area when the availability of feeders was reduced. We suggest that these results may indicate that females invest more to mitigate competition and manage unpredictable access to food due to their subordinate status.

PMID:
42437093
Bibliographic data and abstract were imported from PubMed on 12 Jul 2026.

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