Home
lbbg 1cy May
lbbg 1cy June
lbbg 1cy July
lbbg 1cy August
lbbg 1cy September
lbbg 1cy October
lbbg 1cy Nov - Dec
lbbg 2cy August
lbbg 2cy September
lbbg 2cy October
lbbg 2cy Nov - Dec
lbbg 3cy Jan-April
lbbg 3cy May
lbbg 3cy June
lbbg 3cy July
lbbg 3cy August
lbbg 3cy September
lbbg 3cy October
lbbg 3cy Nov - Dec
ORG-site old links
lbbg sub-ad Jan-April
lbbg sub-ad May
lbbg sub-ad June
lbbg sub-ad July
lbbg sub-ad Aug
lbbg sub-ad Sept
lbbg sub-ad Oct
lbbg sub-ad Nov - Dec
lbbg ad Jan-April
lbbg adult May
lbbg adult June
lbbg adult July
lbbg ad August
lbbg ad September
lbbg ad October
lbbg ad Nov - Dec
|
third calendar year: May
Introduction:
During
winter and especially early spring, 3cy LBBG have undergone a partial moult
in the winter quarters. This moult typically involved the upper-parts, the
under-parts and the head. Also, the bare parts have developed to a more adult-like
coloration. By May, the coverts and tertials often still consist of old feathers
(retained from previous autumn), which strongly contrast with the renewed
grey upper parts (and sometimes the median covert row). However, not every
3cy LBBG follows this sequence, and we have encountered many returning birds with a variable amount of new tertials,
coverts and even rectrices, and 3cy LBBG with a few new primaries
(arrested moult) as well. It's still preliminary to classify LBBG with
arrested moult in the primaries and allocate them to certain populations.
First figures indicate both intermedius from Scandinavia and local
breeding Dutch intergrades may arrest moult in 3cy in spring.
Detailed moult description:
During the month of May an unknown number (but probably a majority) of 3cy birds return to the colonies and NW Europe. The first arrive around April 15th, the majority around May 15th. There may be good reasons for 3cy birds to return (lack of food supply on the wintering grounds, to learn the best feeding grounds around the colony, exploit best breeding places, etc.), but there are risks as well to take on a long journey back to the breeding grounds; especially if a bird will not start breeding yet in a particular year. The strongest argument must be the opportunity to feed for more hours a day compared to areas around the equator (although LBBG feed at sea at night as well).
3cy graellsii visit the colony in May, but numbers are low. Some
3cy birds stay at NW France, at dumping sites and do not return to the
actually breeding sites, although it's only a short distance.
Most 3cy LBBG stay at the edge of the colony. A theory says the brown
feathers in 3cy birds may protect them against the furious attacks of
territory holding adult males. These brown feathers may be signs for
breeders that they do not participate in mating. Nevertheless, severe fighting
is not uncommon. Still, 3cy birds
daily return to the colony and seem to watch the steps of the elder birds.
They may also predate on eggs, young rabbits, etc in the colony. In May, moult activity is very low.
The moult of primaries:
Birds
start shedding the innermost primaries. At the end of May all local birds at
least show a gap of P1 and P2, some birds have already shed P4. Adult and
sub-adult LBBG will start their primary moult from mid-June, dropping P1 and
P2.
Compared to 3cy birds, they have a delay of one or two primaries. New
third
generation primaries in 3cy LBBG are adult-like in having grey centers
and white tips, contrasting with the old plain black-brown second generation primaries. Remarkably, from the second half of May 'new' birds
arrive at the colony, showing delayed primary moult compared to average
3cy. Out of ten birds seen on the last day of May, four birds still had
all the primaries present.
Compared
to older birds, the third generation primaries show: smaller tips, P9
lacks a mirror, P10 has a small sized mirror and P3 and P4 show more black
marks (often resulting in a complete sub-terminal band on P4, where adults
only have black on the outer web).
Nearly always, P10 shows obvious white shafts, when seen from below. This
creates a broad white centre in a pale brown feather, on the underside of
P10. Except for the primaries, there are almost no other feathers shed.
The moult of tail-feathers:
Some
birds start moulting the tail, but May is very early. Most
commonly seen at this age now, is a worn second generation tail,
i.e. a tail with a lot of black, often a broad black tail-band.
Only a few birds are actively moulting some tail-feathers, starting with
the innermost pair. This pair is on top and often easiest bleached and the
tips worn away. Remember that about 30% of the 3cy birds moulted one or
more pairs last winter, resulting in a blocked pattern of white and
non-white tail-feathers. This winter-moult involves tail feathers
randomly, creating an unpredictable black and white tail in spring.
The moult of coverts:
Most
3cy birds still show brownish second generation wing-coverts (greaters
and lessers at least) while upper-parts and bare parts look very
adult-like. In
May, moult in the coverts is not found in birds staying near the colony.
Birds outside the colony may already start moulting at the end of May. New coverts
are easily recognized since this third generation feathers are
typically uniformly grey, like in adults. Some third generation
feathers however (moulted in the previous autumn like the medians, mantle and
scapulars) may be like second generation feathers in pattern, but those
moulted in summer are much more adult-like. The old remaining second generation feathers always show at least some brown in the centre and show
white fringes, but the exact pattern gets lost by wear.
More about arrested and suspended
moult.
The average moult stage for second summer LBBG
can be seen in the pictures. But some odd individuals turn up as well, for
instance with fresh white tips on P1-P7, while P8-P10 are still second generation (and
P10 obviously
lacks a white mirror). It seems that, in both graellsii and intermedius,
arrested moult is a rare phenomenon, but may occur. See image
30-35.
In his article about identification of fuscus
LBBG
(Birding World, 1998), Lars Jonsson writes about 3cy birds:
"Second-summer fuscus is the most likely to be seen as a
vagrant... Overall, they are much blacker than the corresponding plumages
of graellsii and intermedius and they show much more
adult-looking wing coverts. Also, fuscus very typically shows a
staggered or incomplete renewal of the greater coverts, where a few brown
feathers are retained in an otherwise rather blackish row. On the whole,
the more complete renewal of the wing coverts during the pre-breeding
moult is markedly different to that of intermedius and graellsii,
which typically return for their second summer with a new dark grey
'saddle' but old wing coverts (although quite often the median row will
have been renewed, forming a grey band on the middle of the wing)."
And further: "I would positively identify a second-summer Lesser
Black-backed Gull in May showing predominantly dark wing coverts and very
fresh inner six to eight primaries as a fuscus."
Although this all is very true for fuscus,
it may be an over-simplified analysis of what variation 3cy intermedius
may show when they return in May. Most pictures shown here, probably show graellsii
LBBG or Dutch intergrade LBBG as they were taken near or in
colonies in the Netherlands. But on several occasions, groups of true
migrants from Scandinavia can be found at the beach and several
"puzzling" individuals were encountered of which a few are shown
here. It seems that at least one of the key features to look for (i.e.
arrested moult) occurs in intermedius as well and at least an estimated
4-10%
of the 3cy LBBG age-class may show this features in spring. And this may
be a low estimation, since birds with arrested moult are exactly the birds
"in a hurry" and do not take long rests at the stop-over points. It's
interesting to see in what way fuscus-like features have to
accumulate to make identification as fuscus acceptable. Another web page
is enlarging upon and dedicated to several fuscus-features and occurrence of these
features in graellsii/intermedius.
When intermedius shows
arrested moult in the primaries, combined with advanced moult in the upper-parts, these birds can be mistaken for fuscus. At Le Portel,
France, three such LBBG were present early May 2001, including a very
dark, gentle (female) intermedius. The bird's characteristics
strongly approached those said to be diagnostic for fuscus. Very
dark (blackish) gentle (female?) second summer intermedius, which show
very advanced moult in the upper-parts, combined with arrested moult in
the primaries do occur and approach fuscus in
both coloration and general structure. Now we have come across a few LBBGs,
showing third generation P1-P6 or P1-P7, it's
hard to select diagnostic features to distinguish between the two.
Arrested moult or suspended
moult?
In discussions about arrested moult, suspended moult is
included as well. Strictly, the difference between arrested and suspended
moult lies in the continuation:
Suspended Moult: A bird starts moulting the flight feathers in the
ordinary way (from P1 outwards). At a certain point, the moult stops (is
arrested, e.g. when migration starts). After arrival, the bird catches up
moulting the rest of the flight feathers, which can be recognized as
fresher.
Arrested Moult: A bird starts
moulting the flight feathers in the ordinary way. At a certain point, the
moult stops. After arrival, the bird starts moulting P1 again, thus
doesn't continue moulting the rest of the flight feathers.
In some cases moult continuation is combined and two moult waves start:
one wave at P1 and one wave at the place where moult was arrested, prior
to migration. This is visible as two gaps in the wing (beware of secondary
moult in the outer secondaries (S1, S2, S3).
Arrested moult: in autumn or spring?
It may be important in identification to know whether moult was
arrested prior to migration (in autumn) or moult was arrested later on in
winter, prior to northbound migration. Whatever, it might be very
difficult to judge the correct age of flight feathers by their abrasion and wear. In this discussion, it must be said
that there is a
difference between pigment fading (black feather parts fade to
brown, but grey stays grey) and bleaching (all feathers parts,
including the paler parts turn pale). Where this discussion ends is still
open.
Dutch 3cy LBBG at the Maasvlakte
Do the birds we see in the Netherlands represent average Dutch LBBG and do they truly mirror characteristics found in average LBBG? There are about 25.000 breeding pairs at the Maasvlakte. The average reproduction is 1 young: 25,000 1cy birds leave the colony. Already 50% die in the first year (12,500 left) and another 25% die in the second year. Hence, after two years only 9,000 birds remain. If you were able to count all colonies present on the Maasvlakte and surroundings in one moment, you would still miss many birds (1,000's). From the ringed 300 a year, only 9 where seen again the following year (by only 4 observers). But another year later, around 16 birds were recovered, then in their 3cy. Many seem to spend the summer south, where there is no rivalry over nesting places and enough food supply. Others simply linger around, at sea or at other feeding stations like dumping sites.
|
|
E304 graellsii 3cy, May
31 2002, Maasvlakte (Papegaaiebek), the
Netherlands. Ringed in the Netherlands. |
5.366.282 graellsii 3cy, May
07 2003, Maasvlakte (Dintelhaven), the
Netherlands. Ringed in the Netherlands. Arrested primary moult. |
5.366.284 graellsii 3cy, May
27 2003, Maasvlakte (Dintelhaven), the
Netherlands. Ringed in the Netherlands. |
L-97134 graellsii 3cy, May 03 2003, Voorhaven, Zeebrugge, Belgium (51.59N 04.02E). Ringed in Belgium. |
JUH6 intermedius 3cy, May 27 2001, Zeebrugge, Belgium. Picture by P. Adriaens. An intermedius,
born at Vest-Agder, southern Norway, with arrested
moult at P9. May 2001 several LBBG with
arrested moult were recorded. Most probably they origin from
Norwegian colonies. |
DKC
4280679 LBBG intermedius 3cy, May
03 2004, EMO Maasvlakte, the
Netherlands. Ringed in Denmark. Arrested moult at P2. |
Photo
1: LBBG 3cy, May 18 2000, Maasvlakte (Papegaaiebek), the
Netherlands. |
Photo
2: LBBG 3cy, May 12 2001, Missouriweg Maasvlakte, the Netherlands. Note the long-necked and
long-legged appearance in this 2nd summer. |
Photo
3: LBBG 3cy, May 25 2000,
Maasvlakte (Papegaaiebek), the Netherlands. |
Photo
4: LBBG 3cy, May 25 2000,
Maasvlakte (Papegaaiebek), the Netherlands. A very usual bird. |
Photo
5: LBBG 3cy, May 12 2001, Missouriweg Maasvlakte, the Netherlands. Bare
parts like 2cy LBBG, but advanced upper-parts. |
Photo
6: LBBG 3cy, May 25 2000,
Maasvlakte (Papegaaiebek), the Netherlands. |
Photo
7: LBBG 3cy, May 12 2001, Missouriweg Maasvlakte, the Netherlands. In the upper parts, moult progresses slowly, only
half of the scapulars are 3rd generation grey feathers. Tail with many
brown marks. |
Photo
8: 3cy LBBG, May 25 2000, Maasvlakte (Nachtegalenkeet), the
Netherlands. Apart from dark
iris, bare parts typically, including red orbital ring. |
Photo
10: LBBG 3cy, May 26 2000
Maasvlakte (Naaktstrand), the Netherlands. Third and second summer
side-by-side. Note the very pale inner primaries. |
Photo
11: LBBG 3cy, May 23 2002 Missouriweg, Maasvlakte, the Netherlands.
An individual with very obvious head-streaking in May. |
Photo 12: LBBG 3cy, May 2000, Maasvlakte. Compare structural differences in flight between
both birds. |
Photo
14; LBBG 3cy, Maasvlakte, May 26 2000. Correct
ageing of immature LBBGs may be difficult. |
Photo
15: LBBG 3cy, May 12 2001, Dintelhaven Maasvlakte, the Netherlands.
This
typical 2nd summer already frequents the colony. The mantle and scapulars
form a grey saddle. |
Photo
16: LBBG 3cy, May 12 2001, Missouriweg Maasvlakte, the Netherlands. |
Photo
17: LBBG 3cy, May 12 2001, Naaktstrand Maasvlakte, the Netherlands.
Prior to heading north, almost all the median coverts and the inner
greater coverts were shed in one wave. |
Photo
18: LBBG 3cy, May 13 2002, Missouriweg, Maasvlakte, the Netherlands.
Randomly a few coverts were included in the partial moult. |
Photo
19: LBBG 3cy, May 31 2002, EMO, Maasvlakte, the Netherlands. |
LBBG'S WITH
FUSCUS FEATURES |
Photo
30:
LBBG with fuscus features 3cy,
May 5 2001, Dannes, France. A 3cy LBBG with advanced moult stage. P1-p6 show white tips on fresh
primaries. P7-p10 are still 2nd generation.
The dark plumage combined by arrested moult and slender expression
strongly favours fuscus. |
Photo
31:
LBBG intermedius 3cy, May 5 2001, Dannes, France. 3cy winter, as the primaries suggest. In many
respects very advanced and resembling a 4cy LBBG.
Such advanced 3cy LBBG can be found in large groups of intermedius
in spring. |
Photo
32: LBBG
intermedius 3cy,
May 4 2001,
Le Portel, France. Probably a 3cy LBBG, not a delayed 4cy, based on p7-10,
black bill-band and secondaries. |
Photo
33: LBBG 3cy, May 11 2001, Naaktstrand Maasvlakte, the Netherlands. In both graellsii and intermedius, arrested
moult is a rare phenomenon. |
Photo
34: LBBG 3cy / sub-adult intermedius, Le Portel -
Boulogne/Mer, NW France, May 17 2002.
Actively growing p8. |
Photo
35: LBBG 3cy, May 27 2003, Missouriweg Maasvlakte, the Netherlands.
Another example of 3cy LBBG with growing primaries in spring: P8 nearly
fully grown. |
|