Energy requirements of Adélie penguin (Pygoscelis adeliae) chicks

Summary

The energy requirements of Adélie penguin (Pygoscelis adeliae) chicks were analysed with respect to body mass (W, 0.145–3.35 kg, n=36) and various forms of activity (lying, standing, minor activity, locomotion, walking on a treadmill). Direct respirometry was used to measure O₂ consumption ($\dot V_{_{O_{{\text{ 2}}} } } ,l \cdot h^{ - 1}$) and CO₂ production. Heart rate (HR, bpm) was recorded from the ECG obtained by both externally attached electrodes and implantable HR-transmitters. The parameters measured were not affected by hand-rearing of the chicks or by implanting transmitters. HR measured in the laboratory and in the field were comparable. Oxygen uptake ranged from $\dot V_{_{O_{{\text{ 2}}} } } = 1.50 \cdot {\text{W}}^{{\text{0}}{\text{.921}}}$ in lying chicks to $\dot V_{_{O_{{\text{ 2}}} } } = 2.25 \cdot {\text{W}}^{{\text{1}}{\text{.024}}}$ at maximal activity, RQ=0.76. Metabolic rate in small wild chicks (0.14–0.38 kg) was not affected by time of day, nor was their feeding frequency in the colony (Dec 20–21). Regressions of HR on $\dot V_{{\text{O}}_{\text{2}} }$ were highly significant (p< 0.0001) in transmitter implanted chicks (n=4), and two relationships are proposed for the pooled data, one for minor activities ($\dot V_{_{{\text{O}}_{{\text{ 2}}} } } = - {\text{7}}{\text{.23 + 1}}{\text{.82}} \cdot {\text{W + 0}}{\text{.03 HR}}$), and one for walking ($\dot V_{_{{\text{O}}_{{\text{ 2}}} } } = - {\text{11}}{\text{.89 + 1}}{\text{.117}} \cdot {\text{W + 0}}{\text{.58}} \cdot {\text{HR}}$). Oxygen consumption, mass of the chick (2–3 kg), and duration of walking (T, s) were related as $\dot V_{_{{\text{O}}_{{\text{ 2}}} } } = - {\text{0}}.{\text{746 + 1}}{\text{.87}} \cdot {\text{W + 0}}{\text{.076}} \cdot {\text{T}}$, whereas mass-specific O₂ consumption was related to walking speed (S, m·s^-1) as $\dot V_{_{{\text{O}}_{{\text{ 2}}} } } \cdot {\text{W}}^{{\text{ - 1}}} = {\text{1}}.{\text{60 + 7}}{\text{.39}} \cdot {\text{S}}$.