Signal interception and the use of soft song in aggressive interactions

William Searcy, Stephen Nowicki

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

Song sparrows, like many species of songbirds, produce songs of especially low amplitude during aggressive contests. Such 'soft songs' have been shown to be reliable signals of intention to attack in song sparrows. Low intensity is a paradoxical feature in a highly aggressive signal, in that it seems likely to make the signal less intimidating to an opponent. A hypothesis that resolves this paradox is that use of soft songs benefits a signaler by limiting the interception of his signals by third party receivers. Here, we test this hypothesis with respect to song sparrows and two classes of third party receivers, predators and conspecific males. We tested whether selection to avoid predation is responsible for use of soft song by examining whether male song sparrows increase production of soft song in an aggressive context when they also receive signals (alarm calls) that indicate a predator is present. We found that the proportion of soft song produced by male song sparrows was actually significantly lower in the predator context than in a control context, directly contradicting the prediction. We tested whether avoiding eavesdropping by conspecific males is a benefit of soft song by removing territory owners and simulating interactions on their territories using playback from two loudspeakers. We found that intrusions by third party males were more likely in trials in which the simulated owner countered an intruder's songs using soft songs than in trials in which the simulated owner countered with loud song, again directly contradicting the hypothesis. We conclude that limiting interception by predators and conspecific males does not provide an explanation for use of soft song by song sparrows.

Original languageEnglish
Pages (from-to)865-872
Number of pages8
JournalEthology
Volume112
Issue number9
DOIs
StatePublished - Sep 1 2006

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Music
song
interception
animal communication
Sparrows
Passeriformes
predator
predators
alarm signal
Songbirds
songbird
songbirds

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Behavioral Neuroscience

Cite this

Signal interception and the use of soft song in aggressive interactions. / Searcy, William; Nowicki, Stephen.

In: Ethology, Vol. 112, No. 9, 01.09.2006, p. 865-872.

Research output: Contribution to journalArticle

Searcy, William ; Nowicki, Stephen. / Signal interception and the use of soft song in aggressive interactions. In: Ethology. 2006 ; Vol. 112, No. 9. pp. 865-872.
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