Foraging flights of short-tailed shearwaters (Puffinus tenuirostris) from Althorpe Island: Assessing their use of neritic waters

Abstract

The at-sea movement and habitat use of the short-tailed shearwater, Puffinus tenuirostris, were examined using satellite transmitters fixed dorsally to five parents provisioning chicks on Althorpe I., South Australia. Only foraging trips of short duration were targeted by this study, and a range of flight parameters including trip duration, foraging location, total distance covered, and maximum speed were recorded and analysed in order to determine the behaviour of individuals undertaking short duration foraging trips. All short trips were performed during the daytime, and lasted between 16 – 18 hours. During these trips birds foraged exclusively over neritic waters 35 – 70 km to the southwest of the colony. Variable wind conditions did not seem to influence either the direction of flight, or location of foraging activity. Most flight tracks were characterised by fast and direct outbound and return flight, with concentration of time spent (putative foraging activity) in a particular area, suggesting that birds were ‘travelling’ to a known foraging area. However, one track appeared less direct, as the bird frequently changed direction implying that ‘searching’ flight was being performed.