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Bovid Horns: An Important Site for Heat Loss during Winter?
Karine Picard, Donald W. Thomas, Marco Festa-Bianchet and Clément Lanthier
Journal of Mammalogy
Vol. 75, No. 3 (Aug., 1994), pp. 710-713
Published by: American Society of Mammalogists
Stable URL: http://www.jstor.org/stable/1382520
Page Count: 4
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Bovid horns play a prominent role in social and sexual interactions. In cold climates, however, heat loss through the horn surface may represent a major energy cost. We measured surface temperatures of horns ( T h) for two Barbary sheep (Ammotragus lervia; one male and one female) at the Granby Zoo, Québec, using temperature-sensitive radiotransmitters. Over ambient temperatures ( T a) of 5 to -19°C, T h never dropped below 3°C. At T a≈ -10⚬ C, the difference between T hand T a was 17°C for the male and 21°C for the female. Using empirical models to predict heat loss through horns and resting metabolic rates, we estimate that, at T aof≈ -10⚬ C, heat loss through the horn surface is 20% of resting metabolic rate for females and 29% for males which have larger horns than females. We argue that the metabolic costs of possessing large horns in cold climates may impose constraints on morphology and sexual selection.
Journal of Mammalogy © 1994 American Society of Mammalogists