Short abstract from the book: The black-headed gull is the most common gull in Denmark
with an estimated population of 110,000–125,000 breeding pairs. It is furthermore a very common passage migrant and
winter visitor from July to May.
In Denmark the first black-headed gull was ringed in 1910,
with the majority ringed between 1960 and 1990. The blackheaded gull is the most frequently ringed gull. Forty per cent
of the recovered birds were ringed in Jutland, 17 % on Funen,
37 % on Zealand and 4 % on Lolland-Falster. The majority
of the recovered birds were ringed as chicks (61 %), but also
birds ringed as fully grown in winter have been recovered.
Most of the Danish black-backed gulls are migrants. The
one-year-old birds are the first to migrate, and these birds
are recovered in the Netherlands and the British Isles in June.
In July the mean position of one-year-old birds is south of
Denmark. The mean position of adult black-headed gulls
is south of Denmark in August and that of juveniles in
September.
The migration is SW, and in autumn most birds are recovered in the Netherlands, Britain and north Germany. From
August birds have been recovered from the Bay of Biscay and
from October on the Iberian Peninsula. During winter 15 %
of the Danish birds have been recovered in Denmark. Outside
Denmark most have been recovered in the Netherlands, the
British Isles, France, Belgium and Spain. Birds from Jutland
are more frequent in the British Isles than those from eastern
Denmark. Nineteen Danish birds have been recovered in
Africa. The mean position of young birds is further south than
that of older birds.
The Danish black-backed gulls return to Denmark in
March–April. Many one-year-old birds remain abroad in
summer, and only 52 % of the summer recoveries of these
birds are from Denmark. In the following summer 84 % of
the recoveries are from Denmark.
Outside the breeding season many gulls from Norway,
the countries around the Baltic, and northwest Russia have
been recovered in Denmark. The first visitors arrive in late
June and the number of visitors increases in August. Many of
these birds spend the winter in Denmark. The mean position
during summer of birds ringed in Denmark during winter
is northeast of Denmark, indicating that the Danish winter
population is dominated by foreign birds.
The main known cause of death is hunting. Sixty-nine
per cent have been shot in Denmark, mainly in August–
September
Read more about the species in the chapter from The Danish Bird Migration Atlashere
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