The Courish
Spit on the Baltic
Sea (Kurische Nehrung in German) has been
known since the end of the last century for its large concentration
of migrating birds, unique in Europe. The spit is a strip
of sandy terrain, 97 km in length and 0.4 to 3.6 km in width
separating the Courish
Lagoon from the Baltic Sea.
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The chain of sand dunes up to 68 m in
height stretches from the north-east to the south-west which
corresponds to the main direction of bird migration
in this part of Europe. Annually during autumn migration,
over 10 million landbirds of various species that avoid
sea crossings during daytime, use the Courish
Spit as a bridge for their flight.
On some autumn days the number of birds
flying along the spit may reach maxima of 1-2 million,
with an average of 250 000 per day. There is also mass
migration of waterfowl, shorebirds, and waders (swans,
geese, ducks, waders, gulls, rails, coots) over the
spit and the neighbouring parts of the Baltic Sea and
Courish Lagoon. This is especially so in spring. Nocturnal
migration of different taxa over this area takes place
on a broad front and has in autumn seen up to 2.2 million
birds over a front of 1 km. Up to 160-170 bird species
that are known to migrate at night have been recorded.
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Under the leadership of Prof.
Lev Belopolsky who was enthusiastic about
trapping and ringing large numbers of birds,
Janis Jakšis built in 1957 the
first large Rybachy trap. It was made on the same principle
as the Heligoland trap, but differs from the latter in having
a non-rigid body and by its huge size (entrance up to 30 m,
height up to 15 m). The large Rybachy trap resembles a huge
fishing trawl fixed on the ground and open to migrating birds.
Due to the large size of the trap birds do not perceive it
as a source of danger. They enter the trap and in most cases
reach its end chamber by themselves, from where then they
may be extracted by hand. Up to several thousand birds can
be trapped by one standard Rybachy trap a day. Over 2 million
individuals of 186 species have been trapped and ringed during
the 41 years from 1957 to 1998. On average 50 000 to 100 000
are trapped and ringed by this method annually. Passerines
are most commonly caught, e.g. Chaffinch, Siskin, Goldcrest,
Willow Warbler, Great Tit, Starling, etc. The most numerous
non-passerines are Sparrowhawk, Long-eared Owl, Great Spotted
Woodpecker and Cuckoo. Each year the traps are open 24 hours
a day from April 1st till November 1st. This allows a unique
monitoring of diversity, numbers, timing of migration, as
well as sex/age structure, and condition of different birds
arriving from northern and north-eastern Europe.
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Apart from migrating birds, local breeders also get into the
traps. Many of them are repeatedly trapped throughout the
year or in subsequent years, which permit the regular monitoring
of local populations. We have so far obtained 7000 long-distance
recoveries and 20 000 recaptures from our birds ringed. Mass
bird trapping in large traps, taking biometrical data and
ringing is still one of working fields of the Biological Station
Rybachy. The principal aim is to study various aspects of
the avian annual cycle, primarily the migration. Over 85%
of the publications by the station's members are based on
the trapping data.
Various field and experimental studies in the ecophysiology
of migration, avian energetics, avian population ecology were
done in 1967-1989 under the supervision of Prof. Victor
Dolnik. The following long-term projects were conducted:
1. Avian bioenergetics.
2. Physiology of bird migration.
3. Temporal regulation of migration.
4. Orientation and navigation.
5. Site fidelity and dispersal in birds.
6. Avian demography.
7. Population ecology of the Chaffinch.
8. The Experiment project: comparison of different survey
methods of bird migration.
9. The Asia project: strategies of migration in the arid and
highland zones of western Central Asia.
10. Computerization of the ornithological data.
11. Trends in passerine populations.
12. Long-term monitoring of the timing of spring migration
in passerines.
13. Nocturnal migration in birds.
Some projects are still in progress. The following
monographs summarize the most important research results.
Dolnik V.R. 1975. Migratory dispostion in birds. Moscow, Nauka
Publishers.
Payevsky V.A. 1985. Demography of birds. Leningrad, Nauka
Publishers.
Sokolov L.V. 1991. Philoparty and dispersal in birds. Leningrad.
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The
importance of the Courish
Spit for bird migration research became obvious
before the end of the 19th century, when it was first
visited by Johanness
Thienemann, a famous German ornithologist.
In 1901 he established "Vogelwarte
Rossitten", the world's first ornithological
station, in Rossitten, now Rybachy, for the study of bird
migration. J.Thienemann was the head of the station until
1929, followed by Prof. Ernst Schüz. 
"Vogelwarte
Rossitten" was the world's first institution
to start the large scale ringing of birds. E.Schüz
and O.Weigold published the first atlas of bird migration
as early as 1931. World War II interrupted the ornithological
studies on the Courish Spit.
