Abstract
Although avian basal metabolic rate (BMR) has been widely used in interspecific comparative studies, the sources of within-species variation in this parameter are still relatively poorly understood. Individually differing levels of activity and stress responsiveness have been proposed as potential sources for such variation in BMR. Here, I used an open flow-through respirometry system to examine the possible correlates of the time it takes individual Laughing Doves Spilopelia senegalensis to reach lowest oxygen consumption level in a metabolic chamber (‘BMR time’). Also, the association between individual response to handling stress and BMR was studied. Breath rate, measured while holding the bird in hand, was used as a measure of stress response to handling. It was found that ‘BMR time’ was not related to BMR or breath rate. However, its values were positively predicted by individuals' hematocrit. This indicates the potential importance of ‘BMR time’ as an indicator of activity. It was also found that breath rate was individually repeatable when two measurements were taken 12 hours apart. Breath rate was also positively related to BMR; however, the effect disappeared when mass-specific residuals of BMR were used. These results suggest that individual differences in response to standard handling stress probably do not affect BMR measurements.
