Basal metabolic rate and thermal conductance in Arctic Tern chicks and the effect of heat increment of feeding on thermoregulatory expenses

Chick basal metabolic rate (BMRc) as oxygen consumption (VO2 in ml O2 g-1 h-1) of unfed individuals of Arctic Terns Sterna paradisaea during development (12-109 g) was best described by the parabolic equation VO2 = 1.25 + 0.061 m-0.00047m2, where m is body mass in g. Interspecific comparison of hatchling BMRc revealed a relatively high MBRc in Arctic Tern hatchlings, in accordance with an increase in BMRc, with latitude for hatchling terns (Fig. 5). Thermal conductance (h in ml O2 g-1 h-1.degree.C-1). In the chicks was best described by the equation: h = 1.21 m-0.486. In chicks the heat increment of feeding (HIF) in the thermoneutral zone was 1.04 ml O2 g-1 h-1 and not distinguishable from the HIF of 0.92 ml O2 g-1 h-1 at temperatures below the lower critical temperature. The apparent absence of a compensation of thermoregulatory costs with the HIF, is suggested to be due to a more peripherally located thermosensitivity in chicks as compared to adults.

Klaassen M., Bech C. & Slagsvold G, ARDEA 77 (2): 193-200.