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Parental alarm calls suppress nestling vocalization
Dirk Platzen1, Robert D Magrath
1School of Botany and Zoology, Australian National University, 0200 Canberra, Australia. d.platzen@anu.edu.au
Proceedings. Biological Sciences
|August 13, 2004
Summary
Parental alarm calls significantly reduce nestling begging vocalizations in white-browed scrubwrens. This suggests parents play a key role in modulating the costs of honest signaling in young birds.
Area of Science:
- Behavioral Ecology
- Animal Communication
- Evolutionary Biology
Background:
- Signaling theory posits that signal costs ensure honesty.
- Nestling vocalizations (begging) may incur predation costs.
- Parental presence can mitigate these costs by warning young.
Purpose of the Study:
- To investigate the effect of parental alarm calls on nestling vocalizations in white-browed scrubwrens.
- To determine if alarm calls suppress both begging and non-begging vocalizations.
- To assess the influence of nestling age on vocal response to alarm calls.
Main Methods:
- Controlled field playback experiment using alarm and feeding calls.
- Recorded vocalizations of 5-, 8-, and 11-day-old white-browed scrubwren nestlings.
- Measured suppression of begging and non-begging vocalizations in response to playback.
Main Results:
- Parental alarm calls almost completely suppressed non-begging vocalizations.
- Begging calls were only slightly reduced during subsequent feeding call playback.
- Nestling age did not significantly affect vocalization suppression.
Conclusions:
- Parental alarm calls effectively reduce conspicuous non-begging vocalizations, potentially lowering predation risk.
- Parental presence, signaled by alarm calls, informs nestlings about danger, influencing their vocal behavior.
- The cost of nestling vocalizations may be overestimated in studies that do not account for parental influence.