sub-adult: June

Last update of this page: 07-12-03 17:33

Sub-adults in their 3^rd and 4^th summer (fourth calendar year and fifth calendar year respectively) show serious overlap in characteristics. Best clues for ageing these birds is the combination of bare part coloration and age of the primaries and secondaries. Nevertheless, although white tips on the primaries and a mirror on p10 may be expected in 4cy birds, this is not always the case. The same applies for bare parts, which may look very immature in one bird, very adult-like in another while you got the feeling these two have to be born in the same year. In general, sub-adults show:

• very small white tips on the old outer primaries (but beware wear),

• a very limited white mirror on the old p10 and absence of a mirror on p9,

• isolated black markings on old, worn rectrices,

• brown centred coverts, often found in the carpal edge (outer lesser coverts),

• vermiculation on (central) tertials or an accentuated black centre in the tertials, which may have the white tips confined to the inner web,

• immature colouration of bare parts,

• secondaries show brownish centres with a zigzag pattern along the trailing edge.

Arrested and suspended moult

In other sections, much as been said about suspended or arrested moult and by June such birds can be found at the IJmuiden beach and in the Maasvlakte colony (both the Netherlands). For problems related to correct ageing and allocation to specific sub-species, the discussion page can be found here.

- one seen at IJmuiden,
- another seen at IJmuiden,
- another seen at IJmuiden in July,

- birds from the Maasvlakte (the Netherlands) in May 2001,
- a sub-adult in June at the Maasvlakte colony,

- birds at Le Portel (France) on the beach in May,

- possible fuscus at Dannes (France).

Photo 11: LBBG sub-adult, June 17 2001, Naaktstrand Maasvlakte, the Netherlands. An individual, as small as a Common (Mew) Gull.

LBBG sub-adult, June 17 2001, Missouriweg Maasvlakte, the Netherlands. A clear division between p7 and p8. Arrested autumn moult is rare in LBBGs from Western Europe.