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Stabilizing Selection on Body Mass in the Sociable Weaver Philetairus socius
Rita Covas, Charles R. Brown, Mark D. Anderson and Mary Bomberger Brown
Proceedings: Biological Sciences
Vol. 269, No. 1503 (Sep. 22, 2002), pp. 1905-1909
Published by: Royal Society
Stable URL: http://www.jstor.org/stable/3067882
Page Count: 5
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The survival of small birds is often believed to increase with increasing body mass, despite some evidence that body mass is usually maintained below the physiological maximum and that there are costs associated with high body mass, such as increased energetic expenditure and predation risk. In this study, we used an eight-year dataset to investigate survival in relation to body mass in a wild population of sociable weavers (Philetairus socius), a savannah-dwelling passerine bird. We present evidence for strong stabilizing selection on body mass, verifying the prediction that body mass probably results from a trade-off between the risks of starvation at low mass and predation at high mass.
Proceedings: Biological Sciences © 2002 Royal Society