Allometry of alarm calls: black-capped chickadees encode information about predator size.

Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA.
Science (Impact Factor: 31.48). 07/2005; 308(5730):1934-7. DOI: 10.1126/science.1108841
Source: PubMed

ABSTRACT Many animals produce alarm signals when they detect a potential predator, but we still know little about the information contained in these signals. Using presentations of 15 species of live predators, we show that acoustic features of the mobbing calls of black-capped chickadees (Poecile atricapilla) vary with the size of the predator. Companion playback experiments revealed that chickadees detect this information and that the intensity of mobbing behavior is related to the size and threat of the potential predator. This study demonstrates an unsuspected level of complexity and sophistication in avian alarm calls.

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    Les cahiers de l'ED 139: Ethologie 2007-2008, Edited by D. Leeman, L. Nagle, 03/2009: pages 65-95; Presses de l’Université Paris Ouest Nanterre La Défense.
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    acta ethologica 01/2014; · 0.80 Impact Factor
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    ABSTRACT: Interspecific eavesdropping on alarm calling has been considered evidence that species participating in mixed-species groups benefit from reduced risk of predation. Few studies, however, have examined interspecific variation in dependence on and ability to evaluate alarm signals in mixed-species groups. We conducted a playback experiment to evaluate how species in different foraging guilds varied in their response to alarm calls of birds that lead Amazonian mixed-species flocks in both upland and inundated forests. We predicted that species that search nearby substrates myopically would react more strongly to alarm calls (i.e., take longer to resume foraging) than flycatching species that search for insects at a greater distance from a perch. We used likelihood functions to model the latency response to resume foraging for both upland and inundated forests samples, and we were able to detect significant differences among different foraging guilds. Our results indicate that flycatching birds respond weakest in both forest types, but contrary to our predictions, live-leaf gleaners showed a stronger response to alarms than dead-leaf–gleaning insectivores in inundated forest and no difference in upland forest. These results suggest that foraging guild may underlie different levels of dependence on public versus private information and, thus, the dependence of different species on heterospecific informants. These different levels of dependence on alarm calls provide a potential mechanistic basis for un-derstanding assembly rules of flocks.

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May 15, 2014