| When
a white stork was found in Mecklenburg - Western Pomerania
(North-eastern Germany) in 1822 with an arrow sticking in
it, people began to wonder for the first time where these
birds are spending the autumn and winter. This is how research
in to White storks started. For many decades since professional
and amateur scientists have occupied themselves with research
into bird migration with particular focus on the Europeans’
favourite bird - the White Stork. But only in the last eight
to ten years have some completely new facts about stork migration
come to light, which a hundred years of ringing could not
uncover. Here are just some brief examples:
On the autumn migration which often reaches as far as South
Africa, the birds take breaks underway which can last as
long as two months (when there are favourable supplies of
food); comparatively little time is spent in the actual
wintering grounds. The return journey to Europe is made
quickly, but not usually along the same route. Especially
along the European stretch of the route, there are considerable
deviations, and some birds even fly over the Ukraine to
reach Germany.
It is well known that the European storks are divided into
two populations: those which migrate east and those which
migrate west (the eastern storks migrate to Africa via Turkey,
while the western population goes via Spain); up to now
all the indications pointed to the fact that the division
of the migration routes occurs right in the middle of Germany,
but now it has been proved that several eastern German storks
and even some Polish ones also use the western route. In
the middle of Africa, in Chad and the Niger, there is also
an area in which the Eastern and Western storks meet during
their wintering. Far more east European storks fly there
than was previously thought. Further experiments should
prove whether some eastern birds migrate back to Western
Europe with their west European fellow storks, and vice
versa.
One surprising fact was learnt in 1995 thanks to a stork
which had been fitted with a miniature satellite transmitter
in eastern Germany: as far as Turkey it migrated along the
usual east European route, but instead of flying on to Africa,
it went to the Arabian peninsula. This wintering ground
of the eat European storks has been completely unknown up
to then.
In spring 1997 it was possible for the first time to discover
the migration behaviour of homeward flying storks, during
a prolonged period of bad weather in North Africa and the
Middle East. The birds left their wintering grounds in Africa
rather late and the transit of Turkey took 22 days whereas
normally it lasts just three. Many birds perished through
cold and lack of food, and the rest arrived back in the
breeding grounds late and weakened, which reduced the success
rate for breeding considerably.
An individual bird, which left Germany only at the beginning
of September 1992 heading West, "got lost" and
flew in the direction of England instead of Spain. Only
when it reached the English Channel did it turn round and
then flew virtually along the same route back to Germany!
This suggests that migration in White Storks is a collective
phenomenon: birds which fail to leave with their fellow
storks at the right time are often left behind at the breeding
grounds, with uncertain consequences.
A research project into storks is at the moment being carried
out in conjunction with Israeli experts: nearly all east
Europan storks migrate to Africa over this country. The
complementary ecological research being carried out there
has also discovered something new: increasing numbers of
European storks are staying in Israel for the winter and
are giving the onward journey to Africa a miss.
The bird observation post at Radolfzell, Germany, the ornithological
research station of the Max Planck Society, has been using
satellite telemetry in its examination of bird migration.
In a joint project with the Israeli scientists focussing
on White Storks, the foundations were laid which now can
lead to targeted conservation measures under the Bonn Convention.
First draft projects for integrated identification of protected
areas in several countries which are important for white
Stork migration will soon be ready.
It remains to be hoped that modern research and the instruments
of the Bonn Convention will play their part in reversing
the worrying downward trend in the numbers of migratory
species. Professor Dr Berthold, who together with his scientific
team from the Max Planck Institute in Radolfzell has dedicated
himself to looking into bird migration for a long time,
has proved that over the last twenty-five years the number
of migratory birds has declined on average by one per cent
per annum.
We humans must make a turn-around, if we want to avoid
that the next generations blame us for completely impoverishing
their nature heritage.
|
