Vocalizations reveal body condition and are associated with visual display traits in great frigatebirds (Fregata minor)

Frans A. Juola, William A. Searcy

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

Acoustic displays are known to advertise aspects of male quality and to affect female choice of mates in a variety of birds, including not only songbirds but some seabirds as well. Male great frigatebirds (Fregata minor) produce a rapid warble vocalization that forms a prominent part of their courtship display. We investigated the relationships between aspects of this vocalization and male quality and pairing success in 103 great frigatebirds from a population in the northwestern Hawaiian Islands. We found that across males, frequency bandwidth of the display was negatively related to repetition rate, enabling us to use deviation from the upper bound regression of bandwidth on rate ("vocal deviation") as one measure of vocal performance. We used vocal consistency, defined as the coefficient of variation of the time interval between successive peaks in the warble, as a second measure of performance. Vocal deviation was significantly positively associated with body condition of male great frigatebirds, but vocal consistency was not. We found that peak frequency of the warble was not significantly associated with body size but was negatively associated with size of the gular pouch, the most prominent visual ornament. Male great frigatebirds showed significant individual differences in all three vocal measures-peak frequency, vocal deviation, and vocal consistency-but none of these measures was a significant predictor of pairing success in our study population. These results suggest that vocalizations provide honest information about male body condition and gular pouch size in great frigatebirds but do not influence male success in pairing with females.

Original languageEnglish (US)
Pages (from-to)2297-2303
Number of pages7
JournalBehavioral Ecology and Sociobiology
Volume65
Issue number12
DOIs
StatePublished - Dec 1 2011

Keywords

  • Gular pouch
  • Mate choice
  • Peak frequency
  • Sexual selection
  • Vocal performance

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Animal Science and Zoology

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