Referential Alarm Calls Increase Vigilance for Cowbird Brood Parasites in Hosts Such As the Yellow Warbler

Yellow warblers are hosts to brood parasitic brown-headed cowbirds, which rely on other species to raise their offspring. Warblers use referential “seet” calls to warn female warblers specifically of the brood parasitic brown-headed cowbirds that may try to lay eggs in their nests. When exposed to experimental playbacks of seet calls one day, female warblers were more vigilant the next morning, researchers report in the September 15, 2021 issue of Biology Letters. The article is titled “Referential Alarm Calling Elicits Future Vigilance in a Host of an Avian Brood Parasite.” “Playback experiments are a powerful way to study the behaviors of birds in response to parasitic stimuli. Previously, these kinds of referential alarm-calling experiments showed that yellow warblers do something specific right away when they hear the seet call,” said Mark Hauber, PhD, a Professor of Evolution, Ecology, and Behavior at the University of Illinois Urbana-Champaign, a member of the Carl R. Woese Instiute for Genomic Biology, and a fellow of the Wissenschaftskolleg zu Berlin.
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