Fine-scale flight: Using high frequency data loggers to study the at-sea behaviour of wandering albatrosses

Abstract

Albatrosses are large seabirds that function as top predators within the Southern Ocean. Studying their behaviour provides us with valuable ecological information with the potential of indicating changes in marine conditions. Like all seabirds, albatrosses are central place foragers while breeding, returning to their colonies at regular intervals. Consequently, the on-land behaviour of these birds is well studied. However, they are more difficult to study while foraging at sea. Technological advances during the last few decades have seen the development of miniaturised data loggers with long battery life, allowing the recording of fine scale data from several seabird species. We deployed Daily Diary loggers (acceleration data at 16-40 Hz. in conjunction with GPS loggers and miniature cameras on wandering albatrosses (Diomedea exulans. breeding on Marion Island. These data were used to derive the body posture of the birds from the acceleration data and magnetic heading. Daily Diary loggers were calibrated with visual observations from the bird-borne cameras to identify flying behaviour. Bank angles during flight were extracted from video footage using custom-written Python code. Behavioural data were compared to local wind patterns to assess the effect of wind on the flying behaviour of the albatrosses. While commuting albatrosses mainly flew with tail or cross winds, following the predominant wind direction. They were able to deviate from the wind direction by banking more to the relevant side. On average, individual flights lasted 1.25 hours with flapping every ~30s. However some flights lasted > 4 hours with extended periods without flapping (over 20 mins.. Birds flying into headwinds performed shorter flights with more frequent flapping behaviour. Our results give a glimpse into the fine-scale flight behaviour of albatrosses and show the effect of wind strength and direction on their flight patterns. They highlight the value of high frequency loggers to study seabird behaviour. - Abstract as displayed in the - Abstract booklet. The presentation on the day may differ from the - Abstract.