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Oxford, United Kingdom

Dean B.,Animal Behaviour Research Group | Kirk H.,Animal Behaviour Research Group | Fayet A.,Animal Behaviour Research Group | Shoji A.,Animal Behaviour Research Group | And 4 more authors.
Marine Ecology Progress Series | Year: 2015

The role that population-level competition plays in regulating foraging distributions of colonial breeders has remained elusive because many studies of animal movements in the natural environment focus on relatively small datasets from a single population of animals. Here, we present a large (528 foraging trips, 169 individuals), multi-year, multi-colony GPS tracking dataset mostly collected simultaneously at 4 breeding colonies across the core breeding range of a colonially breeding pelagic seabird, the Manx shearwater Puffinus puffinus. Foraging areas were identified by filtering GPS locations (using speed, time of day, and turning angle), validated on a subset of 25 birds carrying co-deployed depth loggers to maximise inclusion of foraging and feeding behaviour. Foraging areas showed high annual variation, but consistent patterns emerged. Birds from each colony consistently foraged locally, showing little overlap between colonies, but birds from all 4 colonies sometimes travelled large distances to forage within a single relatively restricted area. This combined pattern may be driven by density-dependent competition relatively locally, with high overlap and resource sharing at a distance, facilitated by a dual foraging strategy of mixing short and long trips. The key shared area was located near to a tidal front system, the Irish Sea Front, and the stratified waters of the Western Irish Sea to its north and west, which are characterised by high productivity. Visits to this area declined with increasing colony distance, suggesting that foraging advantages are balanced by the energetic costs of travel. Nevertheless, this area is probably of key importance to birds breeding at colonies across the species' core breeding range, highlighting the potential connectedness, and therefore vulnerability, of a pelagic species via a single foraging location, despite apparent segregation more locally around the breeding colonies. © 2015 Inter-Research. Source


Guilford T.,Animal Behaviour Research Group | Biro D.,Animal Behaviour Research Group
Clinical Cancer Research | Year: 2014

Homing pigeons (Columba livia) have been the central model of avian navigation research for many decades, but only more recently has research extended into understanding their mechanisms of orientation in the familiar area. The discovery (facilitated by GPS tracking) that pigeons gradually acquire with experience individually idiosyncratic routes home to which they remain faithful on repeated releases, even if displaced off-route, has helped uncover the fundamental role of familiar visual landmarks in the avian familiar area map. We evaluate the robustness and generality of the routefollowing phenomenon by examining extant studies in depth, including the single published counter-example, providing a detailed comparison of route efficiencies, flight corridor widths and fidelity. We combine this analysis with a review of inferences that can be drawn from other experimental approaches to understanding the nature of familiar area orientation in pigeons, including experiments on landmark recognition, and response to clock-shift, to build the first detailed picture of how bird orientation develops with experience of the familiar area. We articulate alternative hypotheses for how guidance might be controlled during route following, concluding that although much remains unknown, the details of route following strongly support a pilotage interpretation. Predictable patterns of efficiency increase, but limited to the local route, typical corridor widths of 100-200 m, high-fidelity pinch-points on route, attraction to landscape edges, and a robustness to clock-shift procedures, all demonstrate that birds can associatively acquire a map of their familiar area guided (at least partially) by direct visual control from memorised local landscape features. © 2014. Published by The Company of Biologists Ltd | The Journal of Experimental Biology (2014) 217. Source

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