Fig. 1. Mean wind speed (A) at the montane (dashed line) and sea-level (solid line) study sites during measurements of daily energy expenditure. Mean air temperature (B) at the montane (dot-dashed line) and sea-level (solid line) sites and mean standard operative temperature at the montane (dotted line) and sea-level (dashed line) sites. Means were determined from measurements made at 10- or 30-min intervals over 31 days at Tioga Pass Meadow (TPM) and 22 days at Point Reyes Bird Observatory (PRBO).