Calling at a cost: Elevated nestling calling attracts predators to active nests

Tonya M. Haff*, Robert D. Magrath

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    95 Citations (Scopus)

    Abstract

    Begging by nestling birds has been used to test evolutionary models of signalling but theory has outstripped evidence. Eavesdropping predators potentially impose a cost on begging that ensures signal honesty, yet little experimental evidence exists for such a cost at active nests because the use of artificial nests, long playback bouts and absence of parents may have exaggerated costs. We broadcast short periods (1 h) of either nestling vocalizations or background noise at active white-browed scrubwren, Sericornis frontalis, nests. Nestlings called naturally during both treatments, allowing us to test whether elevated calling increases risk, a key but rarely tested assumption of evolutionary models. Predators visited nests exclusively during periods of elevated calling. Furthermore, playbacks affected neither adult visits nor nestling activity, suggesting that calling alone attracted predators. Adults gave alarm calls and nestlings usually called less when predators approached nests. Predation risk to broods is, therefore, likely to fluctuate substantially over short periods of time, depending on nestling hunger and whether adults or young have detected predators. This study confirms a present-day cost of nestling begging, demonstrates that this cost can be incurred over short periods and supports the importance of parent- offspring antipredator strategies in reducing predation risk.

    Original languageEnglish
    Pages (from-to)493-495
    Number of pages3
    JournalBiology Letters
    Volume7
    Issue number4
    DOIs
    Publication statusPublished - 23 Aug 2011

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