Referential alarm calling elicits future vigilance in a host of an avian brood parasite

Abstract

Yellow warblers ( Setophaga petechia ) use referential ‘seet’ calls to warn mates of brood parasitic brown-headed cowbirds ( Molothrus ater ). In response to seet calls during the day, female warblers swiftly move to sit tightly on their nests, which may prevent parasitism by physically blocking female cowbirds from inspecting and laying in the nest. However, cowbirds lay their eggs just prior to sunrise, not during daytime. We experimentally tested whether female warblers, warned by seet calls on one day, extend their anti-parasitic responses into the future by engaging in vigilance at sunrise on the next day, when parasitism may occur. As predicted, daytime seet call playbacks caused female warblers to leave their nests less often on the following morning, relative to playbacks of both their generic anti-predator calls and silent controls. Thus, referential calls do not only convey the identity or the type of threat at present but also elicit vigilance in the future to provide protection from threats during periods of heightened vulnerability.

Animal-friendly behavioral testing in field studies: examples from ground squirrels

“…Within a species, animals can vary alarm vocalizations to encode specific information such as the degree or imminence of danger posed by a predator or potential threat ( Zuberbühler et al, 1997 ; Zuberbühler, 2000 ; Murphy et al, 2013 ; Coye et al, 2015 ; Carlson et al, 2017 ). Because alarm calls communicate information about possible danger, they can elicit specific vigilant or antipredator behavioral responses, as well as physiological responses, in conspecifics who hear the calls ( Mateo, 2010 ; Silvestri et al, 2019 ; McRae, 2020 ; Lawson et al, 2021 ). Evaluation of alarm calls during trapping procedures can provide information about the health status of yellow-bellied marmots ( Marmota flaviventer ; Nash et al, 2020 ).…”