Dynamic soaring decouples dynamic body acceleration and energetics in albatrosses.

Area of Science:

• Animal ecology
• Bioenergetics
• Biologging technology

Background:

• Estimating movement costs is crucial for understanding animal energetics and life-history strategies.
• Overall dynamic body acceleration (ODBA) is a common proxy for energy expenditure (EE) in free-ranging animals.
• The utility of ODBA in species using body rotations or environmental energy for movement is less understood.

Purpose of the Study:

• To evaluate various sensor-derived movement metrics as proxies for EE in albatrosses.
• To determine the effectiveness of ODBA and alternative metrics during dynamic soaring and flapping flight.

Main Methods:

• Two species of albatrosses were equipped with multi-sensor loggers (heart rate, accelerometer, magnetometer, GPS).
• Movement metrics were analyzed against heart rate-derived V̇O2 (an indirect EE measure) during different flight modes.
• Relationships between metrics and EE were assessed during soaring and flapping.

Main Results:

• A metric based on yaw axis angular velocity effectively estimated EE during exclusive soaring in albatrosses.
• ODBA was not a useful proxy for EE during soaring, as albatrosses exploit wind energy.
• The number of flaps was a useful metric for comparing EE across foraging trips, despite lower flapping duration.

Conclusions:

• Body rotations in dynamic soaring have energetic costs, but these are lower than flapping flight.
• ODBA is an inadequate measure of EE for albatrosses due to their extensive soaring behavior.
• Alternative metrics beyond ODBA are necessary for accurately estimating EE from inertial sensors in animals with complex movements like body rotations.