A Eurasian Dotterel equipped with a light-logger in Northern Finland spent almost half a year in the wintering areas in Libya.
The Eurasian Dotterel (Eudromias morinellus) breeds in the arctic-alpine zone of Palearctic. Its wintering range is also sufficiently known: it winters in North Africa eastwards to the Middle East, with some birds reaching the Canary Islands as well.
Ring recoveries have shown that some Dotterel populations winter in specific areas. For example, the British population winters mainly in Morocco. Other European populations migrate over a broad front and their wintering areas are more widespread. The Fennoscandian doterels seem to follow the latter migration pattern.
Despite their undeniable contribution to our understanding of bird migration, ring recoveries have their own limitations. For example, the time spent on migration and at stopover and wintering sites is not known. The migratory connectivity (the geographic connection between the different stages of the annual cycle of an individual or population) is also partially known through bird ringing.
Tracking technologies enter the scene
To gather more details about the migration of Eurasian Dotterel breeding in Fennoscandia, researchers from Norway and Finland used new tracking technologies in addition to the traditional ring recoveries. They shared the results of their project in the International Wader Study Group conference held in Morecambe, UK (Aarvak et al. 2019).
Between 2011 and 2019, Aarvak and colleagues equipped 44 Dotterels with light-loggers (geolocators) in areas in Finland and Norway. Of these, only one bird was recaptured (recapture is necessary to get the data). They also fitted 5 birds with satellite transmitters in Norway (Only two autumn migration tracks to the Black Sea, shown in purple in the map).
Despite low recapture rate of birds with geolocators, the single bird gave very interesting results. The bird spent more time in the wintering areas in Libya (Nafusa Mountains and Sirte) than in the Finnish breeding area (45 % of the annual cycle in Libya and 26% in Finland).
During autumn migration which lasted 58 days, the bird made a single stopover on the Black Sea, Ukraine (54 days). During spring, the bird migrated faster despite following a much longer easterly route and making three stopovers.
Reference:
Aarvak,T. Timonen, S. Gjerstad, D., Väisänen, R. & Pasanen, E. 2019. Light-logger mapping of migratory connectivity of Dotterels breeding in alpine Fennoscandia. Presented at International Wader Study Group conference, Morecambe, UK, September 2019.