Dive patterns observed in double-crested cormorants, and metabolic rate associated with different activities, temperatures and feeding status
| . | . | Temperature (°C) . | Oxygen consumption (ml min-1 kg-1) . | Energy expenditure (W kg-1) . | Factor (×BMR) . | Dive duration (s) . | Surface duration (s) . | Dive/pause ratio . | No. dives per bout . | N . | n . |
|---|---|---|---|---|---|---|---|---|---|---|---|
| BMR | 22.1±1.0 | 13.97±1.57 | 4.59±0.51 | 10 | 27 | ||||||
| Resting in water | |||||||||||
| Post-absorptive | Warm | 15.0±0.7 | 32.98±5.32 | 10.83±1.75 | 2.4 | 8 | 24 | ||||
| Cold | 7.9±0.0 | 44.54±6.81 | 14.62±2.23 | 3.2 | 8 | 21 | |||||
| Absorptive | Warm | 14.6±1.1 | 33.16±5.02 | 11.11±1.68 | 2.4 | 7 | 36 | ||||
| Shallow diving | |||||||||||
| Post-absorptive | Warm | 16.4±1.1 | 61.33±5.91 | 20.14±1.94 | 4.4 | 23.5±2.6 | 20.0±7.5 | 1.7±0.6 | 17.3±7.0 | 9 | 49 |
| Cold | 7.5±0.1 | 71.06±4.80 | 23.33±1.58 | 5.1 | 19.1±3.2 | 21.3±8.2 | 1.4±0.3 | 9.7±3.3 | 7 | 45 | |
| Absorptive | Warm | 15.5±1.2 | 61.34±6.34 | 20.55±2.12 | 4.5 | 23.9±2.9 | 24.9±9.8 | 1.5±0.6 | 14.9±5.2 | 9 | 62 |
| Cold | 7.3±0.1 | 74.05±6.19 | 24.81±2.07 | 5.4 | 23.1±0.9 | 26.8±9.8 | 1.3±0.5 | 8.9±3.4 | 7 | 23 | |
| Deep diving | |||||||||||
| Post-absorptive | Warm | 13.9±1.2 | 76.08±2.61 | 24.98±0.86 | 5.4 | 21.2±3.6 | 14.4±4.3 | 1.7±0.4 | 3.8±0.7 | 7 | 55 |
| Cold | 7.6±1.4 | 83.65±4.00 | 27.46±1.31 | 6.0 | 19.1±1.3 | 13.3±2.7 | 1.7±0.4 | 3.9±0.4 | 7 | 77 | |
| Absorptive | Warm | 13.9±1.2 | 77.66±3.20 | 26.02±1.07 | 5.7 | 21.4±3.9 | 14.6±3.8 | 1.7±0.3 | 4.5±1.3 | 7 | 61 |
| Cold | 7.7±1.3 | 87.40±5.68 | 29.28±1.90 | 6.4 | 19.3±1.8 | 12.9±2.8 | 1.7±0.4 | 4.7±0.6 | 7 | 68 |
| . | . | Temperature (°C) . | Oxygen consumption (ml min-1 kg-1) . | Energy expenditure (W kg-1) . | Factor (×BMR) . | Dive duration (s) . | Surface duration (s) . | Dive/pause ratio . | No. dives per bout . | N . | n . |
|---|---|---|---|---|---|---|---|---|---|---|---|
| BMR | 22.1±1.0 | 13.97±1.57 | 4.59±0.51 | 10 | 27 | ||||||
| Resting in water | |||||||||||
| Post-absorptive | Warm | 15.0±0.7 | 32.98±5.32 | 10.83±1.75 | 2.4 | 8 | 24 | ||||
| Cold | 7.9±0.0 | 44.54±6.81 | 14.62±2.23 | 3.2 | 8 | 21 | |||||
| Absorptive | Warm | 14.6±1.1 | 33.16±5.02 | 11.11±1.68 | 2.4 | 7 | 36 | ||||
| Shallow diving | |||||||||||
| Post-absorptive | Warm | 16.4±1.1 | 61.33±5.91 | 20.14±1.94 | 4.4 | 23.5±2.6 | 20.0±7.5 | 1.7±0.6 | 17.3±7.0 | 9 | 49 |
| Cold | 7.5±0.1 | 71.06±4.80 | 23.33±1.58 | 5.1 | 19.1±3.2 | 21.3±8.2 | 1.4±0.3 | 9.7±3.3 | 7 | 45 | |
| Absorptive | Warm | 15.5±1.2 | 61.34±6.34 | 20.55±2.12 | 4.5 | 23.9±2.9 | 24.9±9.8 | 1.5±0.6 | 14.9±5.2 | 9 | 62 |
| Cold | 7.3±0.1 | 74.05±6.19 | 24.81±2.07 | 5.4 | 23.1±0.9 | 26.8±9.8 | 1.3±0.5 | 8.9±3.4 | 7 | 23 | |
| Deep diving | |||||||||||
| Post-absorptive | Warm | 13.9±1.2 | 76.08±2.61 | 24.98±0.86 | 5.4 | 21.2±3.6 | 14.4±4.3 | 1.7±0.4 | 3.8±0.7 | 7 | 55 |
| Cold | 7.6±1.4 | 83.65±4.00 | 27.46±1.31 | 6.0 | 19.1±1.3 | 13.3±2.7 | 1.7±0.4 | 3.9±0.4 | 7 | 77 | |
| Absorptive | Warm | 13.9±1.2 | 77.66±3.20 | 26.02±1.07 | 5.7 | 21.4±3.9 | 14.6±3.8 | 1.7±0.3 | 4.5±1.3 | 7 | 61 |
| Cold | 7.7±1.3 | 87.40±5.68 | 29.28±1.90 | 6.4 | 19.3±1.8 | 12.9±2.8 | 1.7±0.4 | 4.7±0.6 | 7 | 68 |
Values are grand means ± 1 s.d., which were established from individual bird means. Temperature refers to air temperature in the case of basal metabolic rate (BMR) and to water temperature in all other cases. Effects of body mass were removed from data following Packard and Boardman(Packard and Boardman, 1999);see Materials and methods for details. `Factor' is the energy expenditure of the respective activity expressed in multiples of BMR. All behavioural parameters given for `deep diving' exclude individual shallow dives that birds might have performed during a deep dive trial. N gives the number of birds, while n refers to the number of trials.