Short abstract from the book: In Denmark the common guillemot breeds only at the most
eastern outpost of the country, Græsholm. This colony is estimated at 2,500 breeding pairs.
The first common guillemot was ringed in 1927, with the
majority ringed in the late 1970s. All the recovered common
guillemots have been ringed at Græsholm, 35 % as chicks.
The young common guillemots leave Græsholm in company
with the male in the second half of June, and from July to
September most birds remain in the southern part of the Baltic
Sea. Some leave the Baltic Sea in October, where birds have
been recovered around Zealand and Funen. A few common
guillemots have been recovered in Norway and Britain. Some
birds stay close to the colony year round. In mid-March birds
return to the colony. Most settle in their breeding colony, and
adults are faithful to their breeding site. A few birds born on Græsholm have been recorded in Swedish colonies on Store
Karlsö and Hallands Väderö.
Outside the breeding season, Denmark is visited by common
guillemots from the British Isles (99 % from Scotland). Some
Scottish guillemots have been recovered around Bornholm
and Græsholm, but the majority have been found along the
west coast of Jutland and in Kattegat. Several birds from the
Swedish colonies in the Baltic Sea have been recovered around
Bornholm and Græsholm, many in the breeding season. Many
common guillemots from Heligoland in Germany have been
recovered in Denmark. During their first autumn, many of
the young birds from Heligoland move north along the west
coast of Jutland and from August some have been found in
inner Danish waters.
Read more about the species in the chapter from The Danish Bird Migration Atlashere
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