Fig. 2. Daily body mass losses and derived metabolic rates of isolated, loosely
grouped and free-ranging male emperor penguins during winter (April to July).
Mean daily body mass losses were calculated from published studies
(Prévost, 1961;
Prévost and Sapin-Jaloustre,
1964; Ancel et al.,
1997). Estimated mean metabolic rates were calculated from the
mean daily body mass loss applying Groscolas's method
(Groscolas, 1988) and Ancel et
al.'s results (Ancel et al.,
1997).