first
calendar year: September
Last update of
this page: 28-03-05 20:40
Last year we did a small survey on juvenile
LBBG and moult (n=45). This year the survey was repeated and was done
inside the colony in August. For the results, see the Juvenile LBBG August
Section.
By September, the large majority of
juvenile LBBG have left the Netherlands and must have moved south towards
Portugal. Many of the Dutch juveniles, which were seen moulting the
scapulars in the colony (in August) must have joined these migrating
groups. Nevertheless, many juveniles can still be found in the
Netherlands, but as September progresses, more juveniles from Scandinavian
colonies move in. This may be a reason for the "observed
stand-still" in moult progress in juveniles: those local juveniles
with advanced moult move south and less advanced individuals from
Scandinavia fill the open positions or gather in mixed local groups.
Best option to reduce this problem is
simultaneous counts throughout the West European coastline, or counts
which only involve ringed individuals (thus from certain origin).
The problem of later hatched intermedius, moving into early
moulting graellsii-groups is not a problem restricted to juveniles.
To get a clear picture about arrested primary moult in autumn in adult graellsii
plumage, the best place to look for these adults is probably outside the
Netherlands, at the first major stop-over sites in Portugal for instance.
It is believed that particularly those adults, which arrest primary moult,
may also be keen on migrating south as quick as possible.
Moult score
in body feathers of juvenile LBBG 16.09.2000, Maasvlakte, the
Netherlands.
mantle =mantle + scapulars;
lesser =lesser coverts,
median =
median coverts,
greater = greater coverts,
# = number of
individuals.
Normal pattern: moult in lower neck, followed by
mantle, scapulars, coverts. First moulted coverts are the medians. |
mantle |
lesser |
median |
greater |
# |
0% |
0 |
0 |
0 |
23 |
10% |
0 |
0 |
0 |
3 |
30% |
0 |
0 |
0 |
2 |
40% |
0 |
0 |
0 |
2 |
50% |
0 |
0 |
0 |
1 |
50% |
0 |
1 |
0 |
1 |
50% |
0 |
3 |
3 |
1 |
60% |
0 |
2 |
2 |
1 |
70% |
0 |
0 |
0 |
2 |
70% |
0 |
2 |
0 |
1 |
75% |
0 |
1 |
0 |
2 |
80% |
0 |
2 |
1 |
1 |
80% |
0 |
2 |
6 |
1 |
90% |
0 |
3 |
3 |
1 |
100% |
0 |
1 |
0 |
1 |
100% |
1 |
6 |
1 |
1 |
100% |
3 |
4 |
1 |
1 |
n = 45 exx. |
|
LBBG 'Dutch intergrade' from Belgium
|
LBBG 1cy AMAV
September 23 1999, Westkapelle, the Netherlands. A bird ringed in
Belgium last summer. Photo by Pim Wolf. |
LBBG 1cy ATAM
September 23 1999, Westkapelle, the Netherlands. A bird ringed in
Belgium last summer. Photo by Pim Wolf. |
LBBG 1cy BAAK
September 16 1999, Westkapelle, the Netherlands. A bird ringed in
Belgium last summer. Photo by Pim Wolf. |
LBBG 1cy BCAG
September 23 1999, Westkapelle, the Netherlands. A bird ringed in
Belgium last summer. Photo by Pim Wolf. |
LBBG 1cy BFAS
September 30 2000, Westkapelle, the Netherlands. A bird ringed in
Belgium last summer. Photo by Pim Wolf. |
LBBG 1cy BLB
L-102454
September 02 2003, Westkapelle, the Netherlands. |
LBBG 1cy BLB
L-106159
September 02 2003, Westkapelle, the Netherlands. |
LBBG 1cy BLB
L-106998
September 02 2003, Westkapelle, the Netherlands. |
LBBG 1cy BLB
L-107902
September 02 2003, Westkapelle, the Netherlands. |
LBBG 1cy BLB
L-901162
September 27 2004, Westkapelle, the Netherlands. Picture Pim Wolf. |
LBBG 1cy BLB
L-901365
September 17 2004, Westkapelle, the Netherlands. Picture Pim Wolf. |
LBBG 1cy BLB
L-901703
September 27 2004, Westkapelle, the Netherlands. Picture Pim Wolf. |
LBBG 'Dutch intergrade' from the Netherlands
|
LBBG
1cy SL2
September 09 1998, Westkapelle, the Netherlands. Ringed in the
Netherlands at Maasvlakte this year. Photo by Pim Wolf. |
LBBG 1cy A14E
September 24 2002, Scheveningen, the Netherlands. Bird ringed in the
Netherlands at Maasvlakte last year. |
LBBG
1cy C95 E
September 27 2003, Amsterdam, the Netherlands. A bird ringed left red C95,
right yellow E. |
LBBG 1cy NLA
5.366.174 September
02
2001, Brouwersdam, the Netherlands. |
LBBG 1cy
NLA
5.xxx.166
September 17 2004, Westkapelle, the Netherlands. Picture Pim Wolf. |
LBBG intermedius in September
|
LBBG 1cy
4285037
September 28 2004, Westkapelle, the Netherlands. Picture Pim Wolf. |
LBBG intermedius 1cy
DKC ?9499
September 2004, Westkapelle, the Netherlands. Picture Pim Wolf. |
LBBG intermedius 1cy
J07J
September 22 2002, Boulogne/Mer, NW France. A bird ringed in
Norway last summer.
|
LBBG intermedius 1cy
JNJU
September 17 2004, Westkapelle, the Netherlands. Picture Pim Wolf. |
LBBG intermedius 1cy
Stavanger
4238324,
September 22 2002, Boulogne-sur-Mer, NW France. A bird ringed in
Norway last summer. |
unringed LBBG in September
|
10+
unringed LBBG juveniles |