Reduction of nestlings’ vocalizations in response to parental alarm calls in the Southern House Wren, Troglodytes musculus

SERRA, CATALINA; FERNANDEZ, GUSTAVO J.

JOURNAL FUR ORNITHOLOGIE

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2011 vol. 152 p. 331 - 336

0021-8375

Breeding birds often give alarm calls when apredator is near the nest. These calls have been proposedto serve as distraction displays for the predator, alerts fora mate conveying information about the presence of athreat, or a warning for nestlings about a potential risk.These functions, however, may not be mutually exclusive.In our study, we assessed if alarm calls uttered bybreeding Southern House Wrens, Troglodytes musculus,are made to warn nestlings about risk. If so, we expectedthat nestlings would reduce overall activity in the nest andthat the parents’ call rate would be related to the detectabilityof the young (e.g., vocalizations). We experimentallyelicited parents’ alarm calls and compared nestlingbehavior before and after giving that stimulus. We foundthat Southern House Wren nestlings reduced their timespent vocalizing and remained inactive for longer whentheir parents called. Therefore, nestlings reduced theirdetectability by decreasing their activity inside the nestwhen their parents produced alarm calls. On the otherhand, parental calling rates were not related to the nestlingactivity registered in any experimental stage. Therefore,we failed to find reliable results supporting the hypothesisthat parent calling is uttered to silence nestlings. Theseresults appear to indicate that alarm calling by breedingbirds might fulfill other functions besides alertingnestlings. Future studies of this species are necessary tounderstand if parents are warning nestlings about a threatwhen they emit alarm calls.