Abstract:
The field of Movement Ecology has benefited greatly from the technological advancements of the past three decades, with the advent of tracking technologies, such as GPS and ARGOS satellite telemetry, allowing for a significantly expanded collection of movement data that provides insights into the behaviour of animals. Through the advancement of mathematical models that make use of this data we are able to address questions such as why animals move, how they move, the navigational mechanisms they use and the external factors involved in this process. In this thesis we utilise high resolution movement tracks from a pelagic sea-bird, the Grey-Faced Petrel, to investigate the navigational component of movement; where navigational decisions are made and the external cues that are used. This is done in three steps: (1) we develop mathematical models to classify the tracks into distinct behavioural states, gaining a better understanding of the tracks and locating areas where navigational decisions are likely to have been made; (2) using a novel method we identify ‘turning points’ from the track data, points that indicate a significant change in direction; and (3) we analyse the visual information available to the birds during their flight to assess the possible use of visual landmarks for navigation. The models developed in the first two steps focus on simple implementation, adaptability to a wide range of contexts, fast computation and ability to deal with spatial noise in the tracks, whilst producing accurate, biologically relevant results. We exploit the recently proposed ‘Multi-Scale Straightness Index’, a measure of path straightness, to achieve these goals, adding valuable resources to the literature. The final step introduces a method that can be used on any animal tracks to ascertain the visual perspective of the target and provides evidence that our pelagic bird species utilises distant landmarks to determine its path home. The findings in this thesis form an important contribution to the mathematical and biological literature surrounding the field, facilitating further research into the complex question of how animals find their way.