Heart rate and rate of oxygen consumption of exercising macaroni penguins
Twenty-four macaroni penguins (Eudyptes chrysolophus)
from three groups, breeding males (N=9), breeding females
(N=9) and moulting females (N=6), were exercised on a
variable-speed treadmill. Heart rate (fH) and mass-specific
rate of oxygen consumption (sVO2) were recorded from the
animals, and both fH and sV02 were found to increase
linearly with increasing treadmill speed. A linear
regression equation described the relationship between fH
and sVO2 for each individual. There were no significant
differences in these regressions between breeding and
moulting females. There were significant differences in
these relationships between all females and breeding males.
fH and sVO2 were recorded from five of these animals for a
total of 24 h. When fH was used to predict sV2· for the 24 h
period using the derived regressions, the estimate was notsignificantly different from the measured values, with an
average error of -2.1 %. When fH was used to predict sVO2
for the 5 min intervals used for the calibration in all 24
birds, the estimate was not significantly different from the
observed values, and the average error was only +0.47%.
Since the fH/sVO2 relationship was the same during periods
of the annual cycle when the animals were inactive/fasting
and active/foraging, it seems reasonable that, as long as sex differences are taken into account, fH can be used to predict the metabolic rates of free-ranging macaroni penguins all year round.