Evidence for a reproductive sharing continuum in cooperatively breeding mammals and birds: Consequences for comparative research

Yitzchak Ben Mocha, Tal Dahan, Yuqi Zou, Michael Griesser, Shai Markman

Research output: Contribution to journalReview articlepeer-review


Extreme reproductive skew occurs when a dominant female/male almost monopolizes reproduction within a group of multiple sexually mature females/males, respectively. It is sometimes considered an additional, restrictive criterion to define cooperative breeding. However, datasets that use this restrictive definition to classify species as cooperative breeders systematically overestimate reproductive skew by including groups in which reproduction cannot be shared by definition (e.g. groups with a single female/male). Here, we review the extent of reproductive sharing in 41 mammal and 37 bird species previously classified as exhibiting alloparental care and extreme reproductive skew, while only considering multi-female or multi-male groups. We demonstrate that in groups where unequal reproduction sharing is possible, extreme reproductive skew occurs in a few species only (11/41 mammal species and 12/37 bird species). These results call for significant changes in datasets that classify species' caring and mating system. To facilitate these changes, we provide an updated dataset on reproductive sharing in 63 cooperatively breeding species. At the conceptual level, our findings suggest that reproductive skew should not be a defining criterion of cooperative breeding and support the definition of cooperative breeding as a care system in which alloparents provide systematic care to other group members' offspring.

Original languageEnglish
Article number20230607
JournalProceedings of the Royal Society B: Biological Sciences
Issue number2006
StatePublished - 13 Sep 2023

Bibliographical note

Publisher Copyright:
© 2023 The Authors.


  • birds
  • communal breeding
  • cooperative breeding
  • mammals
  • maternity
  • reproductive skew

ASJC Scopus subject areas

  • General Agricultural and Biological Sciences
  • General Environmental Science
  • General Immunology and Microbiology
  • General Biochemistry, Genetics and Molecular Biology


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