Heart rate as a predictor of energy expenditure in undisturbed fasting and incubating penguins.

• Published in: Journal of Experimental Biology
• Main Authors: Groscolas, R., Viera, V., Guerin, N., Handrich, Y., Côté, S. D.
• Other Authors: Département Ecologie, Physiologie et Ethologie (DEPE-IPHC), Institut Pluridisciplinaire Hubert Curien (IPHC), Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Département de Biologie, Université Laval Québec (ULaval)-Pavillon Alexandre-Vachon, IPEV
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2010
• Subjects: heart rate; energy expenditure; energy pulse; seabird; fasting; incubation; stress; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; King Penguins
• Online Access: https://hal.archives-ouvertes.fr/hal-00444107; https://doi.org/10.1242/jeb.033720

International audience Heart rate (f(H)) measurement offers the possibility to monitor energy expenditure (EE) in wild animals if the EE/f(H) relationship for the species, physiological stages and activities of interest is known. This relationship has been extensively studied using oxygen consumption rate ( ) measurement in captive, repeatedly handled king penguins (Aptenodytes patagonicus). Unfortunately, the potential effects of stress on the observed relationships resulting from handling and confinement were not considered. This study is the first involving undisturbed animals, and determines the EE/f(H) relationship in naturally fasting and freely incubating or captivity-acclimatized male and female king penguins. EE determination was based on (1) the measurement of body mass loss during periods of phase II fasting, and (2) the calculation of its energy equivalent from changes in body composition, i.e. 23.9 kJ g(-1). f(H) levels in freely incubating and captivity-acclimatized birds were found to be 50-70% lower than those previously reported for resting king penguins during measurements. Significant EE/f(H) relationships were found in freely incubating and captive males and females (R(2)=0.59 to 0.84), with no difference observed between genders. The best overall relationship was obtained by including fasting duration (t, days) in the model: EE=818+43.7xf(H)+36.3t-1.4txf(H) (R(2)=0.91). This equation yielded EE estimates approximately 26% higher than the previously reported 'best' predictive equation in king penguins, and even more so when f(H) was low. This result suggests that stress induces a disproportionate increase of f(H) vs O(2) consumption, and that the use of EE/f(H) relationships obtained in stressed birds could lead to underestimated EE values.