1. Distribution of
LBBG in Western Europe
From the 1960's on, the LBBG complex has received great interest. Several studies in the field and from museum specimen have been executed. Until recently, most writers supported the general idea of a clinal change from west to east.
the islands of the U.K., Iceland and the Faeroes, the race
graellsii occurs. Graellsii is obviously different from fuscus
in mantle colour (paler grey), wing dimensions (wing length plotted
against bill length), bill dimensions (graellsii being
blunt-billed, measured by bill height/length) and egg dimensions, together
with timing of egg laying date (all from Barth, 1967-1968 ~ page not available).
occurs in the central and northern Baltic area and in the northern part of
Norway. In general it is very dark mantled (black-grey) and mantle
feathers show more chroma (brownish hue).
between, i.e. southern Norway and Denmark, an intermediate form, intermedius
occurs. It seems reasonable to believe they are a result of interbreeding
(intraspecific hybridisation) between pale graellsii
and dark fuscus. Within a couple of decades intermedius and graellsii
interbreeds started to occupy new sites along the West-European coast from
Denmark southwards (although some sources mention them to be graellsii,
intermedius only being a common visitor on migration). It's an ongoing process, resulting in new colonies already as far south as Portugal. The populations at Iceland and the Faeroes seem to show much resemblance with graellsii and it's believed the LBBG's seen in the U.S. belong to this race as well. Nevertheless, ring recoveries show that first winter LBBG's born in Dutch colonies (often referred to as Dutch intergrades) turn up in the U.S. as well.
Especially since the 60's, graellsii and intermedius
populations have expanded rapidly, while the fuscus population has
decreased. For years, the contact zones of intermedius and fuscus could be found at central Norway (just north of Möre, where nevertheless pretty pale grey specimens were collected) and in Denmark (where it is impossible to distinguish, on sub specific level, between either the Danish sample and the Baltic one or between the Danish sample and the intermediate sample from e.g. the Netherlands). On the island of Anholt, several 100s of breeding LBBGs were found in the 60's; their characteristics varying from 'typical graellsii', 'typical fuscus'
and the intermediate form corresponding with intermedius birds.
map shows the approximate ranges of fuscus, intermedius
and graellsii, as the late Edvard Barth classified LBBG's after
intensive field research. Already in the 60's, Barth proposed to treat intermedius
as a subspecies, or at least classify it closer to graellsii than
to fuscus. Apart from coloration and biometrics, graellsii
and intermedius are different from fuscus in egg laying
date and migration pattern, where fuscus clearly differs from the intermedius/graellsii
group. Ring recoveries revealed fuscus to migrate S and SE, where
main groups of intermedius
catches up with graellsii on their migration SW to Portugal and
further south along the NW African coast. Birds from South Sweden migrate
south, at least a part of the population can be found in E Germany and
further south in S Italy on migration. Probably the birds from Öland
(which have been recorded flying SW) meet birds from Denmark on the way to
S Italy and further south into Africa.
Locations in the Netherlands and NW France
(image left: click numbers to go to locations in the Netherlands.)
what is written on this website deals with LBBG's seen at our local patches
in the Netherlands. Most pictures were taken at these locations as well.
Click on one of the numbers in the map to get a more detailed map of the
locations Westkapelle, Maasvlakte and
IJmuiden. Westkapelle is a place to
study gulls from short distance, especially from September to December.
Near Rotterdam, in the industrial Europoort complex, large Lesser
Black-backed Gull colonies raise their pulli from April to August. Near
Amsterdam, the fishing harbour of IJmuiden has extensive sandy beaches
with large shell-banks where groups of several 1,000's of large white-headed
gulls forage in winter.
round, the direct surrounding of Boulogne-sur-Mer is a very interesting
place to search for white-headed gulls, especially Yellow-legged Gulls.
Boulogne-sur-Mer and the banks of the river Canche at Etaples host several
100's of gulls and make this place the northern-most area in Europe to
study michahellis on a large scale. NW France is only a four hours
drive from Amsterdam. Click the thumbnail of the map for the Le Portel /
Boulogne-sur-Mer locations and some background information.
and Maasvlakte both hold large colonies of LBBG's; Westkapelle in the 'far'
SW of the Netherlands is favorite for spending the months mid-September to
November by Scandinavian LBBG's from S Norway, Denmark and SW Sweden.
(Theo Muusse scanning a flock of over 2.000 gulls on October 18 2002, about 90% are Lesser Black-backed Gulls intermedius and graellsii mixed with Great Black-backed Gulls, Herring Gulls, about 50 Yellow-legged Gulls and 4 Caspian Gulls)
should be noted that the largest part of research on the moult proceedings
of LBBG has been done on the Naaktstrand. This place, a freshwater pool
immediately next to the beach is used as stop-over by breeding birds
returning from the sea. They stay here for only a short period, they preen
and move on to the colony.
nearest colony is situated 1 km from this pool. During the day, numbers
fluctuate with high numbers during morning and late in the afternoon.
Birds then return from their night-hunt on sea. In the late afternoon,
birds gather here to wait for the sunset, the moment they will fly out to
sea to hunt on surface-prey.
stop-over is also a good place to scan migrating LBBG's, colour-rings
indicate birds originate from Belgium, England, Scandinavia and the
Netherlands. But some Pontic Gulls were discovered here originating from
Croatia and the Ukraine.
The 'catman' at Boulogne-sur-Mer. Every morning at 9:00 h. the
cats of the harbour are fed by the catman. And of course he doesn't
forgot the begging first winter Herring Gulls. An ideal option to
search for Lesser Black-backed Gulls, Herring Gulls, Great
Black-backed Gulls, Yellow-legged Gulls, Pontic Gulls, Mediterranean
Gulls, Black-headed Gulls, Common Gulls, .....
differences between graellsii/intermedius and the Baltic fuscus
are arrival at the breeding grounds, first date for egg laying and
migration pattern. Fuscus is tied to another annual pattern or
time-schedule than intermedius
and therefore is bound to another moult pattern, as described by Jonsson
in (BW 11-8, 1998). But if there proves to be overlap in migration
distance, weather conditions on the wintering grounds, etc. this may raise
expectation of overlap in features of fuscus and intermedius
Subsequently, we may find clues to explain similarities in fuscus
intermedius in say "arrested primary moult", "moult
sequence in the retrices and secondaries", etc. We would like to plot
the bulk and extremes of ring-recoveries in a world map for fuscus, graellsii
and intermedius. These data can either refer to metal ring and
colour ring projects. It is necessary to say that many LBBG ring-codes are
read while the birds are still on the move, only indicating their path to
or from the wintering grounds. And certainly, ring-recoveries show
the best visited places by birdwatchers, which are not necessarily the
same as the main wintering grounds.
Main Ring Projects for LBBG
section will follow later on...
Some comments on coloration
the extensive researches of Barth, much emphasize is laid on the different
grey tones and brown hue. Actually, it's not hue as such but the
reflection values what he uses, of which hue is a part, as are value and
chroma. The reflection value consist of:
- Hue: the five
colours (red, blue, yellow, green, purple) have many hues (hue steps
are made in 1-100);
- Value: the relative
lightness are darkness from black (0) to white (10) in 100 steps;
- Chroma: the
'saturation strength' from grey (0) to the 'pure' colour (16)
in decimals steps.
Munsell value therefore can be read as hue/value/chroma. It's interesting
(and highly recommended) to read the results from his various samples from
as far north as N Norway, west from the U.K. and the Faeroes and of course
Sweden, Finland and Denmark. In general, it is possible to distinguish
intermedius and fuscus on a population level, but it is
definitely very hard to allocate individuals to races. Populations vary
from almost black (in SW Finland), becoming slightly paler in N Norway,
Götland and S Sweden and in general become paler grey, where the palest
grey LBBGs are found in isolated colonies at Faeroes and the British
is said about grey tone, applies more or less in a same extend to the
Munsell value, the reflection value or as we used it in these web pages
'brown hue' of different LBBG populations in W Europe. Click here for Grey-scale
and Colour charts.