ALARM CALLS AND CHICK REACTIONS IN THE MOUSTACHED WARBLER, ACROCEPHALUS MELANOPOGON

As in many altricial species, adult moustached warblers alarm call mor e at the nest as the breeding season progresses. This study used the e xperimental human approach method as well as two predator types (plast ic snake and taxidermic raptor) placed at the nest to test the anti-pr edator responses of chicks to parental alarm calls. The probability of chicks making anti-predator responses (ducking and jumping) was stron gly correlated with the probability of adults giving alarm calls. Furt hermore, chicks reacted selectively to different predator types, tendi ng to remain in the nest in response to aerial predators and to jump f rom the nest in response to ground predators. A conceptual framework i s presented identifying the age of chicks when alarm calls are first g iven for the brood value, vulnerability and chick reaction hypotheses. These were tested by comparing the intercept of the regression line f or alarm calls with those predicted by each hypothesis. The results su ggest that the anti-predator response of chicks is the proximate cue f or adult alarm calls. (C) 1996 The Association for the Study of Animal Behaviour