Sensor:
Solar Geolocator

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Solar Geolocator
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    Data package
    Data from: Trans-equatorial migration links oceanic frontal habitats across the Pacific Ocean: year-round movements and foraging activity of a small gadfly petrel
    (2024-01-22) Clay, Thomas A.; Brooke, MdeL.
    Gadfly petrels are among the widest-ranging birds and inhabit oceanic regions beyond the legislative protection of national jurisdictions (the High Seas). Detailed information on breeding phenology, at-sea distributions, and habitat requirements is crucial for understanding threats and designing conservation measures for this highly threatened group. We tracked 10 Stejneger’s petrels Pterodroma longirostris, endemic to Isla Alejandro Selkirk, Juan Fernández Islands in the southeast Pacific Ocean, with geolocator-immersion loggers over two years to examine year-round movements, phenology, habitat use, and activity patterns. Birds conducted round-trip trans-equatorial migrations of 54,725 km to the northwest Pacific Ocean between Hawaii and Japan. Across the boreal summer, birds followed the c. 1000 km northward movement of the North Pacific Transition Zone Chlorophyll Front, before their return migration which took a long detour south toward New Zealand before heading east at 40–50°S, presumably benefitting from Antarctic circumpolar winds. To our knowledge, a comparable triangular migration is unique among seabirds. During the pre-laying exodus, birds traveled southwest to the Sub-Antarctic Front, and unlike congeners, there was no evidence of sexual segregation. Foraging areas during incubation were similar to pre-laying, with trips lasting 13 d and taking birds up to 4810 km southwest of the colony. Petrels spent > 75% of their time flying during breeding and migration, yet flight activity was substantially lower during non-breeding, presumably due to flight feather molt. Birds spent 87% of their time at sea within the High Seas and their apparent preference for oceanic frontal regions demonstrates the importance of protecting these remote habitats.
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    Data from: Loop-migration and non-breeding locations of British breeding Wood Warblers Phylloscopus sibilatrix
    (2022-11-22) Burgess, Malcolm D.; Castello, Joan; Davis, Tony; Hewson, Chris
    Capsule: British breeding Wood Warblers Phylloscopus sibilatrix show a clockwise loop migration incorporating stops in southern Europe, the Sahel, and the humid forest zone of West Africa. Aims: To determine autumn and spring migration routes, the location and duration of stopover sites on migration, and the location of non-breeding areas of British breeding Wood Warblers. Methods: In 2016 and 2018 we deployed geolocators to male Wood Warblers on Dartmoor, Devon, and in the New Forest, Hampshire. We retrieved four geolocators from returning birds in 2017, 2019, and 2020. Results: Male Wood Warblers departed breeding sites in late July and stopped for most of August in central southern Europe, crossed the Sahara by a non-stop night and day flight immediately followed by a short stop, and then migrated west to a longer stopover in the Sahel. Final non-breeding destinations were in an area of West Africa covering Guinea, Sierra Leone, and Liberia. Two were tracked on spring migration, again crossing the Sahara via a non-stop flight before migrating through Western Europe to complete a clockwise loop migration back to Britain. Conclusion: All tracked Wood Warblers used stopovers for at least three weeks in three distinct regions, in central southern Europe, in the Sahel, and in the humid zone of West Africa. Although the limitations of geolocation prevent matching locations with habitat, these regions are broadly characterized by distinct forest or woodland habitat types, which differ from breeding habitat. All four tracks showed similar patterns in route, stopover behaviour, and timings, suggesting they may be representative of males in these breeding populations, and potentially of other British and western European Wood Warbler populations.
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    Data from: Geolocators reveal variation and sex-specific differences in the migratory strategies of a long-distance migrant
    (2021-12-29) Bell, Fraser; Bearhop, Stuart; Briedis, Martins; El Harouchi, Myriam; Bell, Sophie C.; Castello, Joan; Burgess, Malcolm D.
    Songbird populations are in decline all over the world, and our understanding of the causal mechanisms remains surprisingly limited. It is important to identify the extent of individual variations in migratory behaviour to better understand species' ability to respond to environmental change. We describe the annual migratory behaviour of British breeding European Pied Flycatchers Ficedula hypoleuca by using light-recording geolocators. During both autumn and spring migrations, individuals used previously unknown staging areas on the Iberian Peninsula and northern West Africa. Furthermore, partial sex-specific segregation in the location of non-breeding areas was observed within West Africa, with females located west of males. We also found sex-based phenological differences, with females staying longer in non-breeding areas and undertaking the spring Sahara Desert crossing later than males. Irrespective of sex, multiple use of the two predominant staging regions was identified during both migrations, with 63% of individuals stopping more than once in these regions. We also identified instances of migratory behaviours rarely documented in individually tracked songbirds. These include making daytime landfall during the Sahara crossing, and a case of a temporary retreat migration, with an individual aborting a spring Sahara crossing before making a second successful crossing 14 days later. Together, our results show variability in migratory behaviour both between sexes and between individuals. For Pied Flycatchers, such flexible migratory behaviour may increase their resilience to environmental change.
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    Data from: Northwest range shifts and shorter wintering period of an Arctic seabird in response to four decades of changing ocean climate
    (2021-11-29) Patterson, Allison; Gilchrist, H. Grant; Gaston, Anthony; Elliott, Kyle H.
    Climate change is altering the marine environment at a global scale, with some of the most dramatic changes occurring in Arctic regions. These changes may affect the distribution and migration patterns of marine species throughout the annual cycle. Species distribution models have provided detailed understanding of the responses of terrestrial species to climate changes, often based on observational data; biologging offers the opportunity to extend those models to migratory marine species that occur in marine environments where direct observation is difficult. We used species distribution modelling and tracking data to model past changes in the non-breeding distribution of thick-billed murres Uria lomvia from a colony in Hudson Bay, Canada, between 1982 and 2019. The predicted distribution of murres shifted during fall and winter. The largest shifts have occurred for fall migration, with range shits of 211 km west and 50 km north per decade, compared with a 29 km shift west per decade in winter. Regions of range expansions had larger declines in sea ice cover, smaller increases in sea surface temperature, and larger increases in air temperature than regions where the range was stable or declining. Murres migrate in and out of Hudson Bay as ice forms each fall and melts each spring. Habitat in Hudson Bay has become available later into the fall and earlier in the spring, such that habitat in Hudson Bay was available for 21 d longer in 2019 than in 1982. Clearly, marine climate is altering the distribution and annual cycle of migratory marine species that occur in areas with seasonal ice cover.
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    Data from: First records of complete annual cycles in water rails Rallus aquaticus show evidence of itinerant breeding and a complex migration system
    (2020-11-30) Lislevand, Terje; Hahn, Steffen; Rislaa, Sven; Briedis, Martins
    In water rails Rallus aquaticus, northern and eastern populations are migratory while southern and western populations are sedentary. Few details are known about the annual cycle of this elusive species. We studied movements and breeding in water rails from southernmost Norway where the species occurs year‐round. Colour‐ringed wintering birds occurred only occasionally at the study site in summer, and vice versa. Geolocator tracks revealed that wintering birds (n = 10) migrated eastwards in spring to breed on both sides of the Baltic Sea, whereas a single breeding bird from the study site wintered in N Italy. Ambient light records of geolocator birds further indicated that all but one incubated 2–4 clutches per season. By combining information on incubation and movement, we found evidence for itinerant breeding in three individual birds: After a first breeding attempt (one did not incubate), all moved 129–721 km to breed again. This behaviour is rarely recorded in birds and was unexpected because the water rail is described as monogamous with both parents caring for eggs and chicks. The study greatly improves our knowledge about the annual cycle and reproduction in water rails. However, more studies are warranted to evaluate the generality of our findings and causes of breeding itinerancy.
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    Data from: Migratory connectivity at high latitudes: Sabine’s gulls (Xema sabini) from a colony in the Canadian High Arctic migrate to different oceans
    (2016-12-14) Davis, Shanti E.; Maftei, Mark; Mallory, Mark L.
    The world's Arctic latitudes are some of the most recently colonized by birds, and an understanding of the migratory connectivity of circumpolar species offers insights into the mechanisms of range expansion and speciation. Migratory divides exist for many birds, however for many taxa it is unclear where such boundaries lie, and to what extent these affect the connectivity of species breeding across their ranges. Sabine’s gulls (Xema sabini) have a patchy, circumpolar breeding distribution and overwinter in two ecologically similar areas in different ocean basins: the Humboldt Current off the coast of Peru in the Pacific, and the Benguela Current off the coasts of South Africa and Namibia in the Atlantic. We used geolocators to track Sabine’s gulls breeding at a colony in the Canadian High Arctic to determine their migratory pathways and wintering sites. Our study provides evidence that birds from this breeding site disperse to both the Pacific and Atlantic oceans during the non-breeding season, which suggests that a migratory divide for this species exists in the Nearctic. Remarkably, members of one mated pair wintered in opposite oceans. Our results ultimately suggest that colonization of favorable breeding habitat may be one of the strongest drivers of range expansion in the High Arctic.
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    Data from: Full-year tracking suggests endogenous control of migration timing in a long-distance migratory songbird
    (2018-08-07) Pedersen, Lykke; Jackson, Kayla; Thorup, Kasper; Tøttrup, Anders P.
    NOTE: An updated and larger version of this dataset is available. See https://doi.org/10.5441/001/1.4bt7365c. ABSTRACT: Following ongoing technological advances, an increasing amount of full-year tracking data on individual migratory movements is becoming available. This opens up the opportunity to study how migration develops within individuals in consecutive years and the extent to which the migratory program is constrained. Such knowledge is essential for understanding the degree of individual flexibility during the annual cycle, which may help identifying potential bottlenecks, where the range of individual decisions is restricted. In this study, we investigate repeatability in time of a long-distance migratory songbird, the red-backed shrike Lanius collurio, tracked across consecutive years (n = 7). Furthermore, we explore the population variability and dependencies between consecutive events of departure and arrival throughout the annual cycle in this species (n = 15). We find that individuals show high repeatability in timing of departure from their two main non-breeding areas in sub-Saharan Africa. In contrast, low repeatability is found in timing of arrivals to stationary sites throughout the annual cycle. Population variation in timing of departure and arrival was similar across all events, ranging from 30 to 41 days, and was highly dependent on timing of preceding events. We conclude that timing of departures is the key event potentially controlled by the individual innate migration program, while arrivals are more flexible, likely dependent on the environmental conditions experienced en route in red-backed shrikes. Still, apparent flexibility in the individual schedule may be hampered by overall constraints of the annual cycle.
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    Data from: Partial migration in the Mediterranean storm petrel Hydrobates pelagicus melitensis
    (2019-04-23) Lago, Paulo; Austad, Martin; Metzger, Benjamin
    Studying the migration routes and wintering areas of seabirds is crucial to understanding their ecology and to inform conservation efforts. Here we present results of a tracking study carried out on the little-known Mediterranean Storm Petrel Hydrobates pelagicus melitensis. During the 2016 breeding season, Global Location Sensor (GLS) tags were deployed on birds at the largest Mediterranean colony: the islet of Filfla in the Maltese Archipelago. The devices were retrieved the following season, revealing hitherto unknown movements and wintering areas of this species. Most individuals remained in the Mediterranean throughout the year, with birds shifting westwards or remaining in the central Mediterranean during winter. However, one bird left the Mediterranean through the Strait of Gibraltar and wintered in the North Atlantic. Our results from GLS tracking, which are supported by data from ringed and recovered birds, point toward a system of partial migration with high inter-individual variation. This highlights the importance of trans-boundary marine protection for the conservation of vulnerable seabirds.
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    Data from: First evidence of diverging migration and overwintering strategies in glaucous gulls (Larus hyperboreus) from the Canadian Arctic
    (2021-12-29) Baak, Julia E.; Patterson, Allison; Gilchrist, H. Grant; Elliott, Kyle H.
    Many seabird populations differ in their migration strategies, where individuals travel in different directions to separate wintering areas. These migratory strategies may expose individuals to different threats, thus understanding migratory connectivity is crucial to assess risks to populations. Glaucous gulls (Larus hyperboreus) are generalist predators with flexible migratory behaviour that may alter these behaviours in response to climate change and anthropogenic activities, such as access to landfills, yet little is known about their migration. We deployed GPS and GLS tracking devices on glaucous gulls from Coats Island, Nunavut, Canada to obtain the first insights into their migration and habitat use outside of the breeding season. Gulls used two migration strategies during the non-breeding season, where one migrated as far as the Sea of Okhotsk in the Pacific and the remainder (n = 7) wintered in the North Atlantic. Gulls primarily overwintered in pelagic (56%) and coastal (38%) habitats. While in coastal habitats, one gull visited one landfill once, but visits increased with a 1 km and 3 km buffer, suggesting that urban glaucous gulls primarily used non-landfill habitats. This research can be used as a baseline to explore changes in migratory behaviour and inform future conservation of Arctic-breeding gulls.
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    Data from: Locally adapted migration strategies: Comparing routes and timing of northern wheatears from alpine and lowland European populations [Switzerland]
    (2022-06-17) Meier, Christoph M.; Rime, Yann; Liechti, Felix
    The northern wheatear Oenanthe oenanthe has an almost circumpolar breeding distribution in the northern hemisphere, but all populations migrate to sub-Saharan Africa in winter. Currently, tracking data suggest two main access routes to the northern continents via the Middle East and the Iberian Peninsula. These routes would require detours for birds breeding in the European Alps. Our aim was to map the migration routes and determine annual schedules for birds breeding in Switzerland and Austria, using light level geolocators. We compared their migration patterns with birds from a lowland breeding population in Germany. Birds from the Alps cross the Mediterranean Sea directly heading straight to their non-breeding sites. In contrast, birds from Germany travelled further west via the Iberian Peninsula. While the German population initiated autumn migration relatively early, arrival on the wintering sites was nearly synchronous across the three populations. During spring migration, German birds arrived earlier at their breeding grounds than birds from the Alps. A comparison with the literature indicated that the breeding populations in the Alps use their own route and are among the latest to arrive in spring, showing resemblance to the phenology of Arctic breeding populations. Our results indicate that the annual cycle of Alps-breeding wheatears is influenced primarily by breeding ground conditions, and not solely by migration distance.