Fitness benefits of alternated chick provisioning in cooperatively breeding carrion crows

Eva Trapote*, Víctor Moreno-González, Daniela Canestrari, Christian Rutz, Vittorio Baglione

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

1. In most bird species, parents raise offspring cooperatively. In some cases, this cooperation extends to helpers-at-the-nest who assist the breeders with a range of tasks.
2. While cooperative food provisioning might merely arise incidentally, as a result of the efforts of carers that act independently from each other, recent studies suggest that birds may coordinate by taking turns in visiting the nest. However, evidence that such coordination emerges because individuals actively respond to each other's behaviour is controversial, and the potential benefits of carers' alternation remain unknown.
3. We addressed this knowledge gap by analysing a multiyear dataset for cooperatively breeding carrion crows Corvus corone, comprising 8693 nest visits across 50 groups.
4. Our results reveal that turn-taking does occur in this species and that all group members, regardless of their sex and social role (breeder/helper), tend to alternate at the nest with other carers rather than to make repeat visits.
5. Importantly, we found that the body mass of nestlings increased significantly with the degree of carers' alternation, possibly because well-coordinated groups provided food at more regular intervals.
6. Using earlier monitoring data, the observed increase in body mass is predicted to substantially boost postfledging survival rates. Our analyses demonstrate that alternation in nestling provisioning has measurable fitness benefits in this study system.
7. This raises the possibility that cooperatively breeding carrion crows, as well as other bird species with similarly coordinated brood provisioning, exhibit specialized behavioural strategies that enable effective alternation.
Original languageEnglish
Pages (from-to)95-108
JournalJournal of Animal Ecology
Volume93
Issue number1
Early online date11 Dec 2023
DOIs
Publication statusPublished - Jan 2024

Keywords

  • Cooperative breeding
  • Brood provisioning
  • Turn taking
  • Alternation
  • Coordination
  • Helping at the nest
  • Nestling body mass

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