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EURING
Newsletter, Volume 3, July 2001
The historical
distribution of bird ringing in Europe has produced recovery data
which date back nearly one century in some countries. This material
offers a unique opportunity to monitor changes in migratory patterns
and bird-man interactions. However, old recovery data can be not
easy to access to, or to use, and often need a significant effort
in checking and coding. An example of the very interesting results
in the analyses of historical recoveries is offered here by the
case of the German-ringed White Storks, reported by Alexandra Sproll
and Wolfgang Fiedler.
DIGGING
IN OLD DATA: MIGRATION AND CAUSES OF DEATH
IN WHITE STORKS (CICONIA CICONIA) ACCORDING TO
RINGING RECOVERY DATA OF THE VOGELWARTE ROSSITTEN
(EASTERN PRUSSIA) BEFORE THE SECOND WORLD WAR
by
Alexandra Sproll and Wolfgang Fiedler
RESEARCH CENTRE
FOR ORNITHOLOGY OF THE
MAX PLANCK SOCIETY ANDECHS UND RADOLFZELL
VOGELWARTE RADOLFZELL, BIRD RINGING CENTRE
SCHLOSSALLEE 2, D-78315 RADOLFZELL, GERMANY
E-mail: ring@orn.mpg.de
Although we
have many hints about extended changes in migration and other environment-related
behaviour of birds during the last years or decades on one hand
and are on the other hand able to look back at a whole century of
scientific bird ringing, comparisons over the whole period are seldom
done. Old data is often stored on paper only, not coded and difficult
to access with justifyable effort. Moreover, parts of the older
data was teared apart or partly lost during war confusion.
Within the framework
of the Joint Vogelwarte Radolfzell - EURING Migration Project it
seemed especially valuable to make the Rossitten data of early White
Stork ringing available. This has been done recently in a diploma
thesis at Vogelwarte Radolfzell of which some results shall be shown
here. The data is now inserted into the European White Stork recovery
database and large scale analysis has already started.
Methods
Johannes Thienemann,
the founder of the Vogelwarte Rossitten, started ringing of the
White Stork in 1906. Within the shortest time several thousands
of mainly juvenile White Storks were ringed thanks to the help of
many ringers. Only a few years later (1908) the first long distance
recovery was reported. With the White Stork Thienemann had found
the "predestined target species" that made bird ringing internationally
known.
Until the Second
World War members of the Vogelwarte Rossitten marked about 100,000
White Storks with rings in different parts of Europe. These are
the only extensive data that show the whereabouts of individually
marked White Storks in this time except of a few previous or parallel
ringings, mainly in Denmark, Northern Germany and Poland.
About 3000 index-cards
with data of ringing and recovery had to be analyzed. The cards
were originals or they were reconstructed out of publications and
manuscripts after World War II. These data are of birds ringed in
the years 1908-1949. The geographical coordinates of the ringing
and recovery localities (often given as old and meanwhile hardly
known place names) were determined and the standard Euring-Code
was encoded. An additional result of this work is a file containing
2700 old names of places in Eastern Prussia and in Colonial-Africa.
This file is now available for future analysis of further Rossitten
recoveries.
Migration
The analysis
includes the Eastern and Western migrating White Stork populations
(Fig. 1). Half of the storks recovered are ringed in Eastern Prussia
(Fig. 2). The analysis of the time of the recoveries from the autumn
migration indicates also that the birds reach the Sudan in September
and Eastern or South African wintering areas in November (Fig. 3).
Wintering storks were observed in Europe even at the beginning of
the century (Fig. 4), but most of them were ill or in a poor condition.
Causes of
death
The following
causes of recovery were reported, classified by frequency:
| ring
read from the living stork |
27% |
|
bird found with ring (without details) |
25% |
| electrocuted,
collision with wires |
14% |
| "found"
(without details) |
6% |
|
"shot" (without details) |
6% |
| found
hurt |
5%
|
|
hunted (without details) |
4% |
| trapped
through poor condition |
3% |
| starvation
/ thirst |
2%
|
| victim
of fighting with conspecific rival |
1%
|
| ring
found (without details) |
1% |
| other
causes |
6%
|
Comparing the
causes of recovery from the time of Rossitten with today we must
consider that the breeding and ringing areas do not correspond.
Nevertheless some meaningfull figure can be derived (Fig. 5). Fig.
6 illustrates the distribution of the causes of recovery within
Europe, along the migration flyways and at the wintering grounds.
Fig. 1:
All recoveries of White Storks ringed with Vogelwarte Rossitten
rings 1908-1954 (n=2043). White dots: manipulated birds (transported
or tame), grey dots: all others.
Fig. 2: Recoveries
of birds from Eastern Prussia (n=1103). Grey dots: recovery of storks
ringed as nestlings, white dots: ringing age not available.
Fig. 3:
Recoveries within the first autumn migration south of 40° latitude.
Only recoveries with reported dates exact to the month are included
(n=10).
Fig. 4:
Winter recoveries in Europe (1908-1950; n=33).
Fig. 5:
Causes of recovery of ringed White Storks reported as dead at the
beginning and the end of the 20th century.
Fig. 6:
Distribution of the causes of recovery without "unknown" code (1908
- 1954; n= 1922).
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