Browsing by Author "Padget, Oliver"
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- Gadfly petrels use knowledge of the windscape, not memorized foraging patches, to optimize foraging trips on ocean-wide scalesPublication . Ventura, Francesco; Granadeiro, José Pedro; Padget, Oliver; Catry, PauloSeabirds must often travel vast distances to exploit heterogeneously distributed oceanic resources, but how routes and destinations of foraging trips are optimized remains poorly understood. Among the seabirds, gadfly petrels (Pterodroma spp.) are supremely adapted for making efficient use of wind energy in dynamic soaring flight. We used GPS tracking data to investigate the role of wind in the flight behaviour and foraging strategy of the Desertas petrel, Pterodroma deserta. We found that rather than visiting foraging hotspots, Desertas petrels maximize prey encounter by covering some of the longest distances known in any animal in a single foraging trip (up to 12 000 km) over deep, pelagic waters. Petrels flew with consistent crosswind (relative wind angle 60°), close to that which maximizes their groundspeed. By combining state-space modelling with a series of comparisons to simulated foraging trips (reshuffled-random, rotated, time-shifted, reversed), we show that this resulted in trajectories that were close to the fastest possible, given the location and time. This wind use is thus consistent both with birds using current winds to fine-tune their routes and, impressively, with an a priori knowledge of predictable regional-scale wind regimes, facilitating efficient flight over great distances before returning to the home colony.
- Spatial scales of marine conservation management for breeding seabirdsPublication . Oppel, Steffen; Bolton, Mark; Carneiro, Ana Paula B.; Dias, Maria P.; Green, Jonathan A.; Masello, Juan F.; Phillips, Richard A.; Owen, Ellie; Quillfeldt, Petra; Beard, Annalea; Bertrand, Sophie; Blackburn, Jez; Boersma, P. Dee; Borges, Alder; Broderick, Jess; Catry, Paulo; Cleasby, Ian; Clingham, Elizabeth; Creuwels, Jeroen; Crofts, Sarah; Cuthbert, Richard J.; Dallmeijer, Hanneke; Davies, Delia; Davies, Rachel; Dilley, Ben J.; Dinis, Herculano; Dossa, Justine; Dunn, Michael J; Efe, Marcio A.; Fayet, Annette; Figueiredo, Leila; Frederico, Adelcides Pereira; Gjerdrum, Carina; Godley, Brendan J.; Granadeiro, José Pedro; Guilford, Tim; Hamer, Keith C.; Hazin, Carolina; Hedd, April; Henry, Leeann; Hernández-Montero, Marcos; Hinke, Jefferson; Kokubun, Nobuo; Leat, Eliza; Tranquilla, Laura McFarlane; Metzger, Benjamin; Militão, Teresa; Montrond, Gilson; Mullié, Wim; Padget, Oliver; Pearmain, Elizabeth J.; Pollet, Ingrid L.; Pütz, Klemens; Quintana, Flavio; Ratcliffe, Norman; Ronconi, Robert A.; Ryan, Peter G.; Saldanha, Sarah; Shoji, Akiko; Sim, Jolene; Small, Cleo; Soanes, Louise; Takahashi, Akinori; Trathan, Phil; Trivelpiece, Wayne; Veen, Jan; Wakefield, Ewan; Weber, Nicola; Weber, Sam; Zango, Laura; Daunt, Francis; Ito, Motohiro; Harris, Michael P.; Newell, Mark A.; Wanless, Sarah; González-Solís, Jacob; Croxall, JohnKnowing the spatial scales at which effective management can be implemented is fundamental for conservation planning. This is especially important for mobile species, which can be exposed to threats across large areas, but the space use requirements of different species can vary to an extent that might render some management approaches inefficient. Here the space use patterns of seabirds were examined to provide guidance on whether conservation management approaches should be tailored for taxonomic groups with different movement characteristics. Seabird tracking data were synthesised from 5419 adult breeding individuals of 52 species in ten families that were collected in the Atlantic Ocean basin between 1998 and 2017. Two key aspects of spatial distribution were quantified, namely how far seabirds ranged from their colony, and to what extent individuals from the same colony used the same areas at sea. There was evidence for substantial differences in patterns of space-use among the ten studied seabird families, indicating that several alternative conservation management approaches are needed. Several species exhibited large foraging ranges and little aggregation at sea, indicating that area-based conservation solutions would have to be extremely large to adequately protect such species. The results highlight that short-ranging and aggregating species such as cormorants, auks, some penguins, and gulls would benefit from conservation approaches at relatively small spatial scales during their breeding season. However, improved regulation of fisheries, bycatch, pollution and other threats over large spatial scales will be needed for wide-ranging and dispersed species such as albatrosses, petrels, storm petrels and frigatebirds.
- Unexpectedly deep diving in an albatrossPublication . Guilford, Tim; Padget, Oliver; Maurice, Louise; Catry, PauloAlbatrosses are the iconic aerial wanderers of the oceans, supremely adapted for long-distance dynamic soaring flight. Perhaps because of this they are considered poorly adapted for diving1, in contrast to many smaller shearwater and petrel relatives, despite having amphibious eyes2, and an a priori mass advantage for oxygen-storage tolerance3. Modern biologging studies have largely confirmed this view4,5, casting doubt on earlier observations using capillary tube maximum depth gauges1, which may exaggerate depths, and emphasising albatrosses’ reliance on near-surface feeding. Nevertheless, uncertainty about albatross diving remains an important knowledge gap since bycatch in human fisheries (e.g. birds becoming hooked when diving for longline bait fish) is thought to be driving many population declines in this most threatened group of birds6. Here we show, using miniature electronic depth loggers (TDRs), that black-browed albatross, Thalassarche melanophris, can dive to much greater depths (19 m) and for much longer (52 s) than previously thought — three times the maxima previously recorded for this species (6 m and 15 s), and more than twice the maxima reliably recorded previously for any albatross (from 113.7 bird-days of tracking4,5,7). Further evidence that diving may be a significant behavioural adaptation in some albatrosses comes from co-deployed 3-axis accelerometers showing that these deeper dives, which occur in most individuals we tracked, involve active under-water propulsion without detectable initial assistance from momentum, sometimes with bottom phases typical of active prey pursuit. Furthermore, we find (from co-deployed GPS) that diving occurs primarily in the distal portions of long-distance foraging trips, with deeper dives occurring exclusively during daylight or civil twilight, confirming the importance of visual guidance.
- Unexpectedly deep diving in an albatrossPublication . Guilford, Tim; Padget, Oliver; Maurice, Louise; Catry, PauloAlbatrosses are the iconic aerial wanderers of the oceans, supremely adapted for long-distance dynamic soaring flight. Perhaps because of this they are considered poorly adapted for diving1, in contrast to many smaller shearwater and petrel relatives, despite having amphibious eyes2, and an a priori mass advantage for oxygen-storage tolerance3. Modern biologging studies have largely confirmed this view4,5, casting doubt on earlier observations using capillary tube maximum depth gauges1, which may exaggerate depths, and emphasising albatrosses’ reliance on near-surface feeding. Nevertheless, uncertainty about albatross diving remains an important knowledge gap since bycatch in human fisheries (e.g. birds becoming hooked when diving for longline bait fish) is thought to be driving many population declines in this most threatened group of birds6. Here we show, using miniature electronic depth loggers (TDRs), that black-browed albatross, Thalassarche melanophris, can dive to much greater depths (19 m) and for much longer (52 s) than previously thought — three times the maxima previously recorded for this species (6 m and 15 s), and more than twice the maxima reliably recorded previously for any albatross (from 113.7 bird-days of tracking4,5,7). Further evidence that diving may be a significant behavioural adaptation in some albatrosses comes from co-deployed 3-axis accelerometers showing that these deeper dives, which occur in most individuals we tracked, involve active under-water propulsion without detectable initial assistance from momentum, sometimes with bottom phases typical of active prey pursuit. Furthermore, we find (from co-deployed GPS) that diving occurs primarily in the distal portions of long-distance foraging trips, with deeper dives occurring exclusively during daylight or civil twilight, confirming the importance of visual guidance.