Last update of this page: 30-03-05 06:17

Movements

Most LBBG have left the colonies and surrounding feeding grounds near the Maasvlakte (the Netherlands) and migrate south towards France, Portugal and Morocco. By October many remain on continental NW Europe, as north as the south of the Netherlands along the coast at Westkapelle, 65 km south of the Maasvlakte (see map). By the end of October, birds changed their plumage for adult-like upper-parts and under-parts. The primaries and secondaries are third generation (adult-like). Wing-coverts and tertials have been renewed into (at least) third generation feathers and mantle and scapulars are most fourth generation now.

LBBG in 3cy by mid-October

• The bill shows a bill-band of various size. The average birds (79%) show an ”adult” bill with a broad band over the upper and lower mandible (see image 21).

• The bare parts coloration is not as intense as in adults, more lemon and orange.

• The head is heavily streaked by freshly moulted streaked feathers.

• The under-parts are streaked, sometimes only in the hind-neck.

• Mantle and scapulars resemble adults now (being fourth or even fifth generation).

• Tertials exist of newly moulted third generation feathers. The tertials are adult-grey with a white top. Some birds show a more blackish centre on the new third generation tertials 3, 4, 5 and 6.

• The wing-coverts are plain, grey adult-like 3^rd generation feathers. In only a very few you can find some barring. When so, this barring is found on the inner greater coverts, tertials 2-4 and the inner median coverts. Sometimes (in 5%), a few feathers in the greater coverts have not been replaced (see image 4) and create brown interruptions in the new grey row. The old greater coverts normally are number 5-7 (counted from the body). About 95% of 3cy LBBG follows the normal moult sequence: start with the inner 3-4 then continuing with the outermost feathers and moulting these inwards.

• The primary score at the end of October averages 46 with at least P7 fully grown on any bird. The third generation primaries are very adult-like but P10 often shows an obvious smaller mirror (like in image 1), often not reaching the sides of the feather and situated further from the top.

• Secondaries: about 60% shows replaced third generation secondaries by the end of October.

• The under-wing coverts are white.

• The new tail is completely white or with very restricted black markings (20%) on the outer webs (see image 5).

Arrested moult in 3cy LBBG

Some 3cy birds show arrested moult: new inner primaries, up to p6, p7 and p8, with the outermost primaries still old (P7, P8 and P9 respectively). Arrested moult or near arrested moult can be be recognized by the lack of a gap of at least one missing primaries between the fully grown outermost primary and the next innermost old primary. But one has to be cautious: the gap in the primaries caused by active moult is smaller than is shown in adults and about 70% of 3cy birds do not miss a full primary when it is in active wing-moult. Especially when the outer primaries are moulted, this feature is very common. A few example are presented on this page.

1. Birds with a moult gap of less than one primary:
Photo 21 shows a 3cy intermedius ringed in Denmark with P8 already longer than P7 and the outer primaries P9 and P10 still present. A slightly paler grey bird is presented in photo 14. P8 still has to grown a few inches, while P9 is still present. A 3cy bird with some characteristics found in intermedius is shown in photo 13. Again, this bird has P7 fully grown and P8 still growing. P9-P10 are still old. Another bird, which will arrest primary moult at P8 can be found in photo 22. This bird also has many features of (female) intermedius LBBG.

2. Birds with the arrested moult ascertained:
Photo 19 shows a presumed intermedius in 3cy with P8 fully grown and P9-P10 still old second generation. Photo 20 shows another dark grey LBBG, presumable intermedius with arrested moult at P8. This bird has most of the upper-parts and under-parts adult-like as is commonly found in 4cy birds. 

Remarkably, in all birds the primary moult will probably be arrested or has been arrested at P8. In the October sub-adult LBBG section more birds are represented with arrested moult.

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