Table 2.

Energy budget calculations based on either (A) fixed flight costs of 20.5 W* and a minimum requirement during the daylight period when not flying (E=RMR), or on (B) estimated energy expenditure when not flying during the daylight period

Foraging conditions
(A) Flight costs fixed at 20.5 W*
Eflight (kJ day−1)39.7±2.6105.0±11.5167.4±15.8
Enonflight day (kJ day−1)51.7±1.143.5±1.036.2±1.4
MRnonflight day (×BMR)1.84±0.101.59±0.190.87±0.26
Budget fit (kJ day−1)24.6±4.011.8±6.4−10.9±7.5
(B) Flight costs estimated
Enonflight day (kJ day−1)82.4±2.265.0±2.452.2±2.1
Eflight (kJ day−1)33.6±6.095.4±16.9140.4±9.8
MRflight (W)16.99±2.3717.90±1.5617.50±0.78
Budget fit (kJ day−1)000
  • RMR, resting metabolic rate (MR); E, energy expenditure.

    The calculated energy budget components are within bold borders. Budget fit shows the difference between actual and calculated budgets. Values (mean± s.e.m.) are averages from calculations for each individual for each treatment.

  • * Fixed flight costs in A are taken from Hambly et al. (2004).