Bird migration is a phenomenon which has always held a fascination for man.
Although the migration of passerines passes largely unnoticed, that of the
Common Crane is a widely appreciated spectacle. During daylight hours, the birds
fly in V-formations, with numerous variations. By night, it is often their calls
which reveal their presence. A threatened species for many years, the
west-European population in 2004, stood at between 160,000 and 180,000 birds.
In order to gain a better understanding and wider knowledge of Common Crane
migration, the French Crane Network was set up and includes 57 organizations and
associations (list). Its aim is to exchange
data collected from the regions in order to obtain a more accurate forecast of
the birds’ arrival. It also enables the media and general public to be better
informed. The purpose of this analysis is to provide an accurate account of the
migration and wintering of the species during the 2003-2004 season. Clearly,
this synthesis would not have been possible without the help of many spotters
throughout the country, who have provided valuable data. We would like to extend
our grateful thanks to them and to our foreign contributors (particularly the
German and Spanish correspondents) who have often enabled us to assess nocturnal
flights over France.
|2003 : Postnuptial migration|
The first Common Cranes observed (3 in June and up to 6 in July) were summer visitors on the usual site on the Der lake (51/52). One bird appeared on the Temple Lake (10) in July and another was seen in the Lower Rhine (67) region on August 1st, flying towards south-west. One Common Crane was seen in the Creuse (23) on August 9th and on the following day, 13 birds were spotted on the Der lake (51/52). The initial migratory flights were heard during the night in the Corrèze (19) on August 18th and in the Dordogne (24) on the following day. Before the end of the month, another department, the Cher (18), was also involved, with 13 birds. September was relatively calm, with just a few flights in the Allier (03), the Haute-Vienne (87), the Yonne (89), theAube (10) and the Hautes-Pyrénées (65). An unusual sight was the presence of 8 Common Cranes in the Ain (01) on the 20th and a more predictable arrival of 22 birds on the Der lake (51/52) at the end of the month. Flights remained scattered and involved 1,500 Common Cranes up to the night of October 12th, when the beginnings of large waves of birds were becoming noticeable.
The first migratory flights were reported late in the evening on October
12th. 1,300 birds arrived on the Der lake (51/52) on the 13th during the
evening. Between 15.30 and 19 hours, 15,000 Common Cranes left Germany.
Consequently, extensive data accumulated during the night of October 13th
and on the following day. The first regions involved were the Lorraine and
Champagne-Ardenne. In the Meuse (55), 1 280 Common Cranes crossed over
between 18.00 and 19.00 hours. Starting on the 14th, more than 16,000 birds
landed on the Der lake (51/52) and 730 on the Temple Lake (10). On the same
day, large flights were reported in Burgundy : 3,500 in theYonne (89) and
18,000 in the Nièvre (58). Migration continued in the south-east in the
Centre region : 4,300 in the Cher (18) and in the Auvergne, where more than
9,000 birds were counted in the Allier (03). Subsequently, flights were
reported over the Limousin region : 5,300 in the Creuse (23) and 2 300 in
the Corrèze (19). Finally, flights were seen in the Aquitaine region. In
Arjuzanx (40), 350 Common Cranes were counted. There was also intense
activity on October 15th when at least 25,000 birds flew over the country.
On the following day, more than 14,000 Common Cranes were counted in
Arjuzanx (40). On October 19th, at the end of the first wave, 126 birds were
reported in Cousseau (33), 72 in Puydarrieux (65), 3,000 in Captieux
(33/40), 680 on the Temple Lake (10) and just over 18,000 on the Der lake
(51/52). As from October 16th, the Pyrenees were crossed when 15,500 Common
Cranes were reported over the Basque mountains by the O.C.L.. This crossing
was confirmed by the extremely early arrival of 4,400 birds in Extremadure (south-west
Spain) on October 22nd.
An estimated number of at least 80,000 birds were involved in this initial wave. Thereafter, a temporary lull was noted.
Map 1 : Total number of Common cranes
during the first wave
|A large number of Common Cranes left the Rügen
region in Germany between 10.00 and 12.00 hours, meteorological conditions
being particularly favourable. Fine weather increased warm air currents and
a north-easterly wind enabled the birds to economize energy.The arrival of
Common Cranes from the north-east began early in the evening in the Meuse
(55) and in Champagne-Ardenne. Between 6,000 and 8,000 Common Cranes flew
over the Champagne wetlands in the space of 2 hours. The majority landed on
the Der lake (51/52).
As a result, on the 24th, more than 35,000 birds were counted on the
mudbanks bordering the lake and 1,300 on the Temple Lake in the Orient
forest. This stop-over was brief, since the majority left almost immediately.
During this particular day, approximately 20,000 Common Cranes headed for
the south-west. On the same day, 19 birds arrived in the Baie d’Aiguillon
Map 2 : Total number of Common cranes
during the wave
During this period, bird movements were reported here and there
along the migration route. The main observations were made over a period of
4 days : a minimum of 7,000 birds on November 6th and 7th and at least
10,000 on the 10th and 11th, partly involving departures from Champagne and
Map 3 : Total number of Common cranes
during the wave
Migration : final day (07/12/03)
At least 5,000 Common Cranes left the Der lake (51/52). The
movement was rapidly confirmed by the observation of 11,000 Common Cranes
flying over the Nièvre (58), a figure which amply illustrates the importance
of flight numbers on this particular day. As well as the birds leaving
Champagne, at least 5,000 birds arrived from Germany. This date marked the
end of the 2003 postnuptial migration.