Although I still maintain an interest in the evolution of animal signals, especially warning signals, which was the subject of my early research, I now concentrate on trying to unravel the mechanisms by which animals map the environments through which they travel. What cues do birds use to navigate home across familiar areas? What do their maps look like? How versatile is the spatial knowledge they store?
The questions range from cognitive to ecological, homing pigeons are the principal model, and the techniques involve field experiments using miniature GPS loggers, on-board cameras, and analytical approaches borrowed from computational engineering. Most recently I have been extending my research group’s work to trying to understand how long distance wandering seabirds (many of which are of vulnerable conservation status) migrate, map and navigate across the open oceans.
Additional Information
I have a strong interest in promoting the public understanding of biological science through TV and radio.
Publications
Young frigatebirds learn how to compensate for wind-drift
October 2020
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Journal article
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Proceedings of the Royal Society B: Biological Sciences
Compensating for wind drift can improve goalward flight efficiency in animal taxa, especially amongst those that rely on thermal soaring to travel large distances. Little is known, however, about how animals acquire this ability. The great frigatebird (Fregata minor) exemplifies the challenges of wind drift compensation because it lives a highly pelagic lifestyle, travelling very long distances over the open ocean but without the ability to land on water. Using GPS tracks from fledgling frigatebirds, we followed young frigatebirds from the moment of fledging to investigate whether wind drift compensation was learnt and, if so, what sensory inputs underpinned it. We found that the effect of wind drift reduced significantly with both experience and access to visual landmark cues. Further, we found that the effect of experience on wind drift compensation was more pronounced when birds were out-of-sight of land. Our results suggest that improvement in wind drift compensation is not solely the product of either physical maturation or general improvements in flight control. Instead, we believe it is likely that they reflect how frigatebirds learn to process sensory information so as to reduce wind drift and maintain a constant course during goalward movement.
Short-term behavioural impact contrasts with long-term fitness consequences of biologging in a long-lived seabird
September 2020
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Journal article
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Scientific Reports
Natal imprinting to the Earth’s magnetic field in a pelagic seabird
July 2020
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Journal article
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Current Biology
Manx shearwater (Puffinus puffinus) rafting behaviour revealed by GPS tracking and behavioural observations
Patterns of at-sea behaviour at a hybrid zone between two threatened seabirds.
October 2019
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Journal article
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Sci Rep
Patterns of behavioural variation and migratory connectivity are important characteristics of populations, particularly at the edges of species distributions, where processes involved in influencing evolutionary trajectories, such as divergence, mutual persistence, and natural hybridization, can occur. Here, we focused on two closely related seabird species that breed in the Mediterranean: Balearic shearwaters (Puffinus mauretanicus) and Yelkouan shearwaters (Puffinus yelkouan). Genetic and phenotypic evidence of hybridization between the two species on Menorca (the eastern and westernmost island in the breeding ranges of the two shearwaters, respectively) has provided important insights into relationships between these recently diverged species. Nevertheless, levels of behavioural and ecological differentiation amongst these populations remain largely unknown. Using geolocation and stable isotopes, we compared the at-sea movement behaviour of birds from the Menorcan 'hybrid' population with the nearest neighbouring populations of Balearic and Yelkouan shearwaters. The Menorcan population displayed a suite of behavioural features intermediate to those seen in the two species (including migration strategies, breeding season movements and limited data on phenology). Our findings provide new evidence to support suggestions that the Menorcan population is admixed, and indicate a role of non-breeding behaviours in the evolutionary trajectories of Puffinus shearwaters in the Mediterranean.
Shearwaters know the direction and distance home but fail to encode intervening obstacles after free-ranging foraging trips.
October 2019
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Journal article
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Proceedings of the National Academy of Sciences of the United States of America
While displacement experiments have been powerful for determining the sensory basis of homing navigation in birds, they have left unresolved important cognitive aspects of navigation such as what birds know about their location relative to home and the anticipated route. Here, we analyze the free-ranging Global Positioning System (GPS) tracks of a large sample (n = 707) of Manx shearwater, Puffinus puffinus, foraging trips to investigate, from a cognitive perspective, what a wild, pelagic seabird knows as it begins to home naturally. By exploiting a kind of natural experimental contrast (journeys with or without intervening obstacles) we first show that, at the start of homing, sometimes hundreds of kilometers from the colony, shearwaters are well oriented in the homeward direction, but often fail to encode intervening barriers over which they will not fly (islands or peninsulas), constrained to flying farther as a result. Second, shearwaters time their homing journeys, leaving earlier in the day when they have farther to go, and this ability to judge distance home also apparently ignores intervening obstacles. Thus, at the start of homing, shearwaters appear to be making navigational decisions using both geographic direction and distance to the goal. Since we find no decrease in orientation accuracy with trip length, duration, or tortuosity, path integration mechanisms cannot account for these findings. Instead, our results imply that a navigational mechanism used to direct natural large-scale movements in wild pelagic seabirds has map-like properties and is probably based on large-scale gradients.
