Nestlings reduce their predation risk by attending to predator-information encoded within conspecific alarm calls

Ahmad Barati,Paul G Mcdonald

doi:10.1038/s41598-017-11528-y

Ahmad Barati, Paul G Mcdonald

Open Access

https://doi.org/10.1038/s41598-017-11528-y

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Journal: Scientific Reports	Publication Date: Sep 15, 2017
Citations: 12	License type: open-access

Affiliation: University of New England, Malayer University

Abstract

Predation is one of the main threats to altricial nestlings, with predators often locating nests via eavesdropping on begging signals. Nestlings may be able to adjust their begging based on the current level of risk by monitoring both intra- and interspecific alarm calls near the nest. We show that noisy miner (Manorina melanocephala) nestlings can differentiate between terrestrial and aerial alarm calls of their own species, as they suppressed begging behaviour for longer in response to terrestrial rather than aerial alarm calls. This differential response is potentially due to greater danger that terrestrial calls encode. In contrast, nestlings ignored alarm calls of the sympatric grey butcherbird (Cracticus torquatus) and continued to beg but reduced begging intensity in response to the non-alarm calls of a sympatric eastern rosella (Platycercus eximius), suggesting nestlings were likely responding based upon similarity to a known signal as opposed to expressing a learnt behaviour. Results show that nestlings respond adaptively to two different intraspecific alarm signals but have not learnt to respond to the alarm calls of sympatric species. These suggest that nestlings are able to take advantage of the complex vocal repertoire that adults produce, although discernment is an issue when filtering out irrelevant stimuli.

Highlights

In many animal taxa, offspring produce begging signals to solicit food from parents[1]
The rate of begging call production in control periods prior to stimulus playback did not differ between broods exposed to different playback types (GLMM: χ23 = 2.28, p = 0.51)
There was a significant decrease in begging rates in response to aerial alarm calls (GLMM, χ21 = 87.14, p < 0.001), chur alarm calls (GLMM, χ21 = 66.88, p < 0.001) and rosella chatter calls (GLMM, χ21 = 24.86, p < 0.001) (Fig. 3)

Summary

Introduction

In many animal taxa, offspring produce begging signals to solicit food from parents[1]. Nestlings typically live in environments where they could potentially eavesdrop on the alarm calls of other species to further mitigate their predation risk This eavesdropping on the alarm cues or signals of other species may well provide an important opportunity to acquire additional predator information, either through innate mechanisms or learnt responses[22]. Innate responses to interspecific alarm calls are most likely if calls are similar between taxa[23], while learnt responses most arise through personal experience or social learning from other nestlings[24]. In these previous studies, research was conducted at a time when the offspring were able to respond with movement. We know that parental alarm calls might suppress nestling vocalisations[8], how nestlings adjust their vocalisations in response to different intraspecific alarm call signals is not currently well known

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