Referential alarm calls increase vigilance in brood parasite hosts

[PhysOrg]

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 current issue of the journal Biology Letters.

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