Finding the balance: the effect of the position of external devices on little penguins

• Main Authors: Chiaradia,Andre, Ropert-Coudert,Yan, Healy,Marg, Knott,Nathan
• Format: Report
• Language: English
• Published: Phillip Island Nature Park/National Institute of Polar Research/Phillip Island Nature Park/Department of Zoology, University of Melbourne 2005
• Subjects: little penguins; balance; external devices; swimming; accelerometers; power analysis; Polar bioscience
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=6224; http://id.nii.ac.jp/1291/00006224/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=6224&item_no=1&attribute_id=18&file_no=1

Many studies on the foraging behaviour of penguins rely on data collected with back-mounted data recorders, which can greatly affect the drag of swimming birds. In recent years, the size of devices has been minimised to reduce drag. In addition, devices have been positioned on the lower back of penguins to reduce the effect of the flow separation caused by the device on the penguinユs body. Nevertheless, a device placed on the lower back of penguins is further away from the centre of gravity which may make balancing and swimming difficult. In this study, we used accelerometers to measure and test quantitatively whether the heaving and surging acceleration (as a measure of imbalance) of penguins swimming through a winding channel was different when an external accelerometer was positioned on the lower back compared to the middle of the back (closer to the centre of gravity).Heaving acceleration was different only for two of the seven penguins when a device was placed on the lower back rather than the middle of the back. While the difference was statistically significant, it was too small (less than 1 m/s2) to indicate a difference in the swimming behaviour. Although surging acceleration was consistently different in all seven penguins, we suspect this measurement indicated differences in acceleration between two parts of the body (tail and middle back) rather than an effect in balance. Overall, it seems that the balance of little penguins is not greatly affect by positioning of a device. Nevertheless, further experiments with free-ranging penguins are needed to evaluate fully whether the positioning of a device can affect balance of a penguin swimming on the water surface or its buoyancy when diving in the water.