Niche construction through a Goldilocks principle maximizes fitness for a nest-sharing brood parasite

Nicholas D. Antonson, Wendy M. Schelsky, Deryk Tolman, Rebecca M. Kilner, Mark E. Hauber

Research output: Contribution to journalArticlepeer-review


Generalist brood parasites that share nests with host nestlings can optimize resource acquisition from host parents by balancing the benefits that host nest-mates provide, including attracting increased provisions to the nest, against the costs of competing with the same host young over foster parental resources. However, it is unclear how parasitic chicks cope when faced with more nest-mates than are optimal for their survival upon hatching. We suggest that, in the obligate brood parasitic brown-headed cowbird (Molothrus ater), chicks use a niche construction strategy and reduce larger, more competitive host broods to maximize the parasites' survival to fledging. We experimentally altered brood sizes to test for Goldilocks principle patterns (i.e. a 'just right' intermediate brood size) of cowbird survival in nests of prothonotary warbler (Protonotaria citrea) hosts. We found that intermediate brood sizes of two host nestlings maximized cowbird fledging success relative to 0 or 4 host nest-mates at hatching. Specifically, cowbird nestlings lowered host brood sizes towards this optimum when placed in broods with more host nestlings. The results suggest that cowbirds reduce, but do not eliminate, host broods as a niche construction mechanism to improve their own probability of survival.

Original languageEnglish (US)
Article number20221223
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1982
StatePublished - Sep 14 2022


  • niche construction
  • Protonotaria citrea
  • brood reduction
  • brood parasitism
  • cowbird
  • Molothrus ater

ASJC Scopus subject areas

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


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