Environmental physiology of the banner-tailed kangaroo rat—II. Influences of the burrow environment on metabolism and water loss

Abstract

1. 1. Oxygen consumption and evaporative water loss were measured in response to burrow and control temperature, water vapor pressure and inspired CO 2 concentration for Dipodomys spectabilis. 2. 2. Oxygen uptake of banner-tail kangaroo rats increased in response to increased inspired CO 2 and decreased temperature. 3. 3. Oxygen consumption of the kangaroo rats decreased in response to a combination of elevated CO 2 and water vapor pressure, relative to elevated CO 2 in dry air. but there was no consistent response to increased water vapor pressure, alone or in combination with temperature. 4. 4. Evaporative water loss and heat loss decreased with decreasing temperature and/or increasing water vapor pressure, but water loss increased at elevated inspired CO 2 concentrations and decreased in response to the combination of elevated CO 2 and water vapor. 5. 5. Seasonal acclimatization of oxygen consumption was evident when data were plotted as responses to control exposures by month. 6. 6. Oxygen uptake and heat loss measured under burrow conditions were related to the seasonal thermal cycle, in that metabolism decreased and heat loss increased during the months of highest burrow temperatures. 7. 7. Evaporative water loss showed little seasonal change under either control or burrow conditions, but had a slight increase in September and October, months in which burrow water vapor pressure was reduced .