4/3/2019

GPS loggers - A tale of two migrations

A few weeks ago, we posted a blog about our annual field-trip to Cornwall where the Woodcock Watch team are running a long-term mark-and-recapture study. As well as ringing woodcock, a small sample were tagged with GPS loggers: small tracking devices that record their location but need to be recovered to access the data stored on board. We have been deploying these tags since 2016 and, this winter, have recovered seven of those deployed in previous years. This is one of a series of blogs describing the results these tags have provided (the previous blog can be found here.

A Tale Of Two Map

These two birds both migrated to Northern Russia and spent summer in the Republic of Karelia, close to Finland. Fuchsia shows consistent spring and autumn migrations whereas Blue takes two very different paths. Blue takes a southerly route in spring travelling round the Baltic via Lithuania, Latvia and Estonia. In autumn, Blue travels to the north of the Baltic via Finland and Sweden, crossing the sea at the Aland Islands and the Danish island of Laeso. In both spring and autumn, large sea crossings directly over the Baltic are avoided.

Unusually, however, the final leg of Blue’s autumn migration sees him/her flying west from Denmark and entering Britain on the north Norfolk coast. Previously, we’ve seen satellite-tagged birds take a more continental route, travelling through Germany and the Netherlands and crossing the Channel. This may suggest that Blue had not taken this Scandinavian route before.

Both Blue and Fuchsia began their autumn migration on the same day, the 24th October. So, did Blue’s northerly or Fuchsia’s southerly route prove a more efficient method? It appears there’s not much in it, it took both of them six days exactly!

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