Mimicry-dependent lateralization in the visual inspection of foreign eggs by American robins

Hannah M. Scharf, Katharine Stenstrom, Miri Dainson, Thomas J Benson, Esteban Fernandez-Juricic, Mark Erno Hauber

Research output: Contribution to journalArticlepeer-review


Brain lateralization, or the specialization of function in the left versus right brain hemispheres, has been found in a variety of lineages in contexts ranging from foraging to social and sexual behaviours, including the recognition of conspecific social partners. Here we studied whether the recognition and rejection of avian brood parasitic eggs, another context for species recognition, may also involve lateralized visual processing. We focused on American robins (Turdus migratorius), an egg-rejecter host to occasional brood parasitism by brown-headed cowbirds (Molothrus ater) and tested if robins preferentially used one visual hemifield over the other to inspect mimetic versus non-mimetic model eggs. At the population level, robins showed a significantly lateralized absolute eyedness index (EI) when viewing mimetic model eggs, but individuals varied in left versus right visual hemifield preference. By contrast, absolute EI was significantly lower when viewing non-mimetic eggs. We also found that robins with more lateralized eye usage rejected model eggs at higher rates. We suggest that the inspection and recognition of foreign eggs represent a specialized and lateralized context of species recognition in this and perhaps in other egg-rejecter hosts of brood parasites.
Original languageEnglish (US)
Article number20190351
JournalBiology Letters
Issue number7
StatePublished - Jul 26 2019


  • Avian brood parasitism
  • Egg rejection
  • Hemisphere
  • Mimicry

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Agricultural and Biological Sciences(all)


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