Table 1.

Biometrics, activity and energetics in different foraging environments

Foraging conditions
RichIntermediatePoorTreatmentTimeOrder
Mass and flight muscle
Body mass (g)79.8±2.472.7±2.164.2±1.4F1,12=104, P<0.001***ns
Muscle depression (mm)2.31±0.243.21±0.173.39±0.25F1,12=18.0, P<0.005nsns
Activity
Travel distance (km day−1)7.84±0.3820.38±2.1631.84±2.74F1,12=97.1, P<0.001nsns
Flight time (min day−1)32.2±2.185.4±9.3136.1±12.8F1,12=95.8, P<0.001nsns
Flight speed (m s−1)4.08±0.083.92±0.09F1,202=17.6, P<0.001+*ns
Measured energetics
Assimilation efficiency0.826±0.0100.843±0.0140.840±0.016F1,12=2.76, P=0.12+**ns
MEI (kJ day−1)149.8±5.6189.2±20.3215.5±9.5F1,12=14.4, P<0.005nsns
DEE (kJ day−1)153.8±5.1192.3±16.2220.2±10.1F1,12=22.9, P<0.001nsns
Enight (kJ day−1)37.79±1.0131.92±1.2227.54±1.17F1,12=65.8, P<0.001nsns
BMR (W)0.861±0.0190.776±0.0190.692±0.029F1,12=53.3, P<0.001nsns
BMRms (mW g−1)10.85±0.4010.69±0.2710.76±0.28F2112=0.03, P=0.88ns+*
  • Values are means ± s.e.m. (N=7 birds).

    MEI, metabolisable energy intake; DEE, daily energy expenditure; E energy expended; BMRms, mass-specific BMR.

    Flight speed was only measured in the poor and rich environment.

    Test statistics are from GLMMs with bird identity as a random effect (see Materials and methods). `Time' is time elapsed since the start of the experiments and `order' is whether the first measurements were in the poor or rich environment (`+' indicates higher values in rich environment). ns, P>0.05, *P<0.05, **P<0.01, ***P<0.001.