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Load lightening in the cooperatively breeding acorn woodpecker depends on the analysis

Koenig, Walter1; Walters, Eric2

Published Jun 08, 2026 on Dryad. https://doi.org/10.5061/dryad.4j0zpc8t3

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Abstract

Despite empirical and experimental work in a variety of taxa, a general understanding of investment strategies in cooperative breeders has proven difficult. Analysis of provisioning patterns in the cooperatively breeding acorn woodpecker (Melanerpes formicivorus) reveals that whether birds reduce their investment when assisted by other individuals depends on the analytical approach, including the type of data used as an index of effort and the time span over which it is measured. Estimated by group composition over the course of a complete nesting effort, provisioning is compensatory, with birds reducing their feeding rates in larger groups. In contrast, when measured by provisioning effort of other group members on a short-term, individual watch basis, provisioning is additive, with birds matching the feeding rates of other group members. Both the time frame over which patterns of parental and parental-like care are made and the type of data used need to be considered to understand investment strategies by individuals in social groups.