We evaluated the possible use of a sexually dimorphic plumage trait as a status signal in inter- and intrasexual social interactions in free-living house sparrows, Passer domesticus. Males with larger black throat patches (bibs) tended to be dominant regardless of the opponent's sex. This relationship was maintained after controlling for body size and age in multivariate analyses. However, the nature of social interactions varied according to the sex of the opponent and a male's bib size. Males with larger bibs tended to be less aggressive to male opponents, and received significantly less aggression from those birds, a key predicted benefit of a status signal. However, when the opponent was a female, males with large bibs displayed significantly more aggression than males with small bibs, and this relationship persisted even after controlling for the dominance status of the participants. Females were significantly more aggressive towards male opponents than towards female opponents, and females interacting with two males of known bib size were more aggressive to the one with the larger bib. These results suggest that the bib of male house sparrows may be a signal of status, but that in interactions with females, the bib may also have other functions. Frequent testing by females of the underlying quality being signalled by the bib may be linked to later mate choice, and might be adaptive if the information value of the bib varies among years. Such testing may also contribute to mechanisms for maintaining the bib as a reliable signal of status.
|Number of pages||11|
|State||Published - Jun 1 2003|
Bibliographical noteFunding Information:
We greatly appreciate the help of other members of the house sparrow research team, including Meg Hatch, Ian Stewart, Tria Kinnard, Jennifer Weiskittle and Donna Landrum. This project was supported by a grant from the National Science Foundation and by the University of Kentucky. We also appreciate the tolerance of the staff of the U.K. Agricultural Research Station towards our work. The study was conducted under approval from the Institutional Animal Care and Use Committee of the University of Kentucky, Lexington (Protocol No. 00013L-2000). Finally, we thank Ann Baker, Meg Hatch, Tria Kinnard, Ian Stewart, Doris Watt and an anonymous referee for comments on the manuscript.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Animal Science and Zoology