A Finnish Red-throated Diver wintered on the English Channel

An international research project for studying migration routes and wintering areas of the Red-throated Diver with geologgers has been going on for several years. One Finnish female diver was monitored with the aid of a geologger from summer 2014 to summer 2015. This female was the first Finnish Red-throated Diver which has been monitored all over the year.

The female was ringed earlier and at least four years old in summer 2014. It was trapped on 21^st August 2014 in her nest-site for fitting the geologger. The nest-site situated in Uusimaa, southernmost Finland.

The bird started its autumn migration on 11^th September. The following day it was already in the middle parts of the Baltic Sea, and on 14^thSeptember close to the Danish Straits. From 15^th October to 15^thDecember the female stayed in a limited area on the German and Danish North Sea, possibly moulting. From the North Sea the bird continued its flight to the English Channel where it stayed from 1^st January to 15^thFebruary 2015.

In spring this female Red-throated Diver migrated much more rapidly than in the previous autumn. The migration flight started in the beginning of Mach, and the bird arrived in the Finnish Baltic Sea already on 23^rd March. It started nesting on 8^th May in the previous nest-site, but the clutch was destroyed due to disturbance. The female laid a repeat clutch which was successful. The bird was trapped for taking the geologger away for data analysis on 20^th July, close to the end of the incubation period.

The data showed that this female stayed over the mid-winter on the English Channel, further away than the majority of the earlier winter-time ringing recoveries of the Finnish birds have shown.