Please use this identifier to cite or link to this item: http://hdl.handle.net/1893/286
Appears in Collections:Biological and Environmental Sciences Journal Articles
Peer Review Status: Refereed
Title: Assessing the aerodynamic effects of tail elongations in the house martin (Delichon urbica): Implications for the initial selection pressures in hirundines
Authors: Park, Kirsty
Evans, Matthew
Buchanan, Katherine Louise
Keywords: Flight performance
Tail streamers
Hirundines
sexual selection
Natural selection
Issue Date: Oct-2000
Publisher: Springer Verlag
Citation: Park K, Evans M & Buchanan KL (2000) Assessing the aerodynamic effects of tail elongations in the house martin (Delichon urbica): Implications for the initial selection pressures in hirundines, Behavioral Ecology and Sociobiology, 48 (5), pp. 364-372.
Abstract: Of the three species of Hirundine that breed sympatrically across the U.K., one, the barn swallow, has outer tail feathers elongated into streamers, whereas the other two species, the house martin and the sand martin, do not. The tail streamer of the barn swallow is regarded as a classic example of a sexually selected trait. Recent evidence, however, has suggested that streamers may have evolved largely through natural selection for enhanced flight performance and increased maneuverability. We tested the hypotheses that small streamers 1) increase performance in turning flight, but 2) decrease performance in flight variables related to velocity. We manipulated the lengths of house martin outer tail feathers and measured changes in their free-flight performance, using stereo-video to reconstruct the birds’ 3D flight paths. Five flight variables were found to best describe individual variation in flight performance. Of these five, the three variables determining maneuverability predicted that flight performance would be optimized by a 6 to 10mm increase in the length of the outer tail feathers. In contrast, for mean velocity and mean acceleration, extension of the outer tail feathers appears to have a detrimental effect on flight performance. We suggest that the initial selection pressure for streamers in ancestral short-tailed ‘barn swallows’ was via natural selection for increased maneuverability. In addition, we propose that the benefits of increased maneuverability has differed between hirundines in the past, such that the cost of increasing the length of the outer tail feather has, to date, outweighed the benefits of doing so in streamer-less hirundines.
Type: Journal Article
URI: http://hdl.handle.net/1893/286
DOI Link: http://dx.doi.org/10.1007/s002650000250
Rights: The original publication is available at www.springerlink.com
Affiliation: Biological and Environmental Sciences
University of Stirling
University of Stirling

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