Allometric estimation of metabolic rate from heart rate in penguins

Studies of the relationship between heart rate (fH) and rate of oxygen consumption (V˙O2), which are then used to predict field metabolic rate, frequently fail to incorporate body mass as a predictive variable. This is a potentially important omission in the study of animals whose body mass fluctuates substantially during their annual cycle. In an attempt further to improve estimates of field metabolic rate from fH, we re-evaluated data on Mb, fH and V˙O2 from previous studies of macaroni penguins (Eudyptes chrysolophus) and king penguins (Aptenodytes patagonicus) and derived a new relationship to integrate these three quantities. This relationship is at least as accurate and precise as previously determined relationships. We applied this same principle to published data on 11 of the 20 recognised penguin taxa to derive a relationship to predict V˙O2 from fH and Mb in penguins of any species. This result has interesting implications in terms of reducing the logistical burden in studies of field metabolic rate.