Use of overall dynamic body acceleration for estimating energy expenditure in cormorants Does locomotion in different media affect relationships?

The way in which animals use and acquire energy is fundamental to their fitness. Overall dynamic body acceleration (ODBA) has recently been suggested as a new method for the determination of energy expenditure in wild animals. Although the relationship between ODBA and energy expenditure has been calibrated using gas-respirometry, it has only been validated for animals moving in a single medium. In this work we examined whether the relationship between ODBA and energy expenditure varies between activity types and in particular, how locomotion in different media affects the regressions using the Imperial Cormorant Phalacrocorax atriceps as a model species. Regressing mean ODBA values for resting, diving and walking periods on a single graph against mean power values, the mass-specific power (W kg(-1)) was related to ODBA via; Power = 12.09 + 41.31 ODBA (r(2) = 0.93). Although values for resting, walking and swimming all fell close to a single linear fit, values for flight deviated substantially from this. The different relationships found between locomotory types are discussed in terms of the muscle groups involved in each kind of behavior. (C) 2011 Elsevier B.V. All rights reserved.