Short abstract from the book: The willow warbler is a very common breeding bird in all
parts of Denmark. It arrives at the breeding grounds from
mid-April and departs in August-September. Migrants pass
through Denmark in large numbers from mid-April to early
June and from August to early October. In Denmark the
first willow warbler was ringed in 1923, with the highest
numbers ringed in 1985 and 1990 (nearly 12,000). Only
the robin has been ringed in greater numbers. The majority
of the recovered birds were ringed during migration at the
migration hotspots, mainly in May and to a lesser extent in
August. The willow warblers ringed in Denmark belong to the
population migrating SW from the breeding areas in southern
Scandinavia: only one bird has been recovered north of 34°N,
and none of the birds has either been ringed or recovered in
Finland. The mean position is in Denmark from May to
August. Fifteen per cent of the August recoveries were south of
Denmark, and by September the mean position is in southern
Germany. Early birds have been recovered in northern France
on 23 July, in Switzerland on 15 July and in Morocco on 6
August. Most of the birds migrate via the Iberian Peninsula
and northwest Africa. A few birds, probably belonging to
populations breeding further north or east, have migrated
SE to the eastern Mediterranean (Egypt, Libya and Greece).
Two birds have been recovered during winter in Ghana (16
December) and the Côte d’Ivoire (8 January), which together
with a spring recovery from Mali (16 May) indicates that
the birds winter in West Africa south of the Sahara. During
spring, birds have been recovered in the Mediterranean from
15 March to 10 May. The spring passage of the Mediterranean
is further east than in the autumn. The first bird was recovered in Denmark on 15 April, but the mean position is not in
Denmark until May. Fast birds migrated from Chriatiansø
to Læsø (332 km) and from Blåvand to Lista (300 km) in
one day. Most of the recovered birds were recorded by ringers
(70 %). Of 216 dead birds, most had collided with windows,
been hunted, collided with vehicles or were killed by cats.
Read more about the species in the chapter from The Danish Bird Migration Atlashere
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