干旱区生态环境知识资源中心

We quantified metabolic power consumption as a function of wind speed in the presence and absence of simulated solar radiation in rock squirrels, Spermophilus variegatus, a diurnal rodent inhabiting arid regions of Mexico and the western United States. In the absence of solar radiation, metabolic rate increased 2.2-fold as wind speed increased from 0.25 to 4.0 m . s(-1). Whole-body thermal resistance declined 56% as wind speed increased over this range, indicating that body insulation in this species is much more sensitive to wind disruption than in other mammals. In the presence of 950 W . m(-2) simulated solar radiation, metabolic rate increased 2.3-fold as wind speed was elevated from 0.25 to 4.0 m . s(-1). Solar heat gain, calculated as the reduction in metabolic heat production associated with the addition of solar radiation, increased with wind speed from 1.26 m W . g(-1) at 0.25 m . s(-1) to 2.92 m W . g(-1) at 4.0 m . s(-1). This increase is opposite to theoretical. expectations. Both the unexpected increase in solar heat gain at elevated wind speeds and the large-scale reduction of coat insulation suggests that assumptions often used in heat-transfer analyses of animals can produce important errors.