The effects of temperature and artificial rain on the metabolism ofAmerican kestrels (Falco sparverius)

American Kestrel (Falco sparverius) Science Article 5

abstract

The effect of rainfall on the metabolism of birds is poorly understood. We measured the metabolism as rate of oxygen consumption (V? O2)of four male and four female American kestrels (Falco sparverius) using open-circuit respirometry. We measured V? O2 during the spring atambient temperatures (Ta) of 5, 10, 15, and 25 8C in air without rainfall and with simulated rainfall of 2.5 (low rainfall) and 6.1 cm h1 (highrainfall). Kestrel metabolism was significantly higher when exposed to the two rainfall levels compared to no rainfall. However, kestrelmetabolism was not significantly different at the two rainfall levels. Body temperature (Tb) was significantly lower under high rainfallcompared to low rainfall. In addition, under both rainfall levels Tb decreased with decreasing Ta. Calculated thermal conductance wassignificantly higher in kestrels exposed to rain compared to no rainfall. Kestrels may use sleeking behavior at high rainfall levels to decreasewater penetration of the plumage. Daily energy expenditure (DEE) of kestrels exposed to rain may increase markedly, and kestrel energeticsmay be further exacerbated by wind that often accompanies natural rainstorms.D 2004 Elsevier Inc. All rights reserved.

Glenn R. Wilson, Sheldon J. Cooper, James A. Gessaman, Comparative Biochemistry and Physiology, Part A 139 (2004) 389- 394

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