nominate Lesser Black-backed Gull (L. f. fuscus)

(last update: 18-11-2009)

Coordinators:
Amir Ben Dov (Israel)
Hannu Koskinen (Finland)
Mars Muusse (the Netherlands)

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fuscus ad Jan
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fuscus ad April
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fuscus unringed Aug
fuscus ad Sept
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fuscus ad Nov
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4cy fuscus: March

Images presented in this section are from Israel, where nominate fuscus is a regular visitor.


Larus fuscus fuscus migarting flock, March 25 2013, Ashdod, Israel. Picture Amir Ben Dov.

Primary moult

The moult sequence in nominate Lesser Black-backed Gull Larus fuscus fuscus was already described by Stresemann & Stresemann in 1966 in Journal für Ornithologie. They described a periodische Staffelmauser, a step-wise moult. Normally, large white-headed gulls in Europe start replacement of the remiges during the breeding season and finish this moult in autumn, prior to their migration.

Stresemann & Stresemann described fuscus as an exception as it doesn't start the remiges moult before arriving at the wintering grounds in Africa and the Mediterranean. For a long-distance migrant like fuscus, this seems to be a suitable strategy. This pattern can also be found in long-distance migrants like Terns (Sternidae).

Stresemann & Stresemann examined skin collections and failed to find any adult L. f. fuscus originating from the breeding or autumn migratory range that was in active primary moult. Therefore they presumed the entire moult stage takes place on the wintering grounds. Adult birds on migration had been collected (Rossitten Bird Observatory, Russia) and these birds confirmed the theses: they must have suspended moult, as Heinroth (1928, Die Vögel Mitteleuropas) concluded: adult fuscus doesn't show active primary moult on migration. They either suspend moult or do not commence moult before arrival on the wintering grounds.

However, there are a few museum skins that do show adult fuscus in primary moult: the Zoological Museum of Helsinki (not visited by the Stresemanns in 1966) has 21 skins of summer / early autumn birds: 8 are showing moult in the primaries. The museums of Copenhagen and Tring have 10 skins in collecting from the same period: one is showing active primary moult.

The last decades, the general idea about the renewal of the primaries in adult fuscus has been changed slightly. Field research showed that a small majority (up to 60% in southern Sweden) of the adult fuscus have started to replace the inner one or two primaries on the breeding ground by late August. This primary moult is suspended until arrival at the tropical wintering grounds. Fuscus complete their primary moult in February and March, just before leaving again to the breeding grounds in Scandinavia and northern Russia. By March, the inner primaries may in some birds included in the primary moult, in a second wave. This seems to be a common feature in sub-adult birds.


Larus fuscus fuscus migarting flock, March 28 2013, Ashdod, Israel. Picture Amir Ben Dov.

1cy fuscus in August, ringed in Finland. (81365 bytes)L. f. fuscus 4cy? C60J March 26 2013, Ashdod, Israel. Picture: Amir Ben Dov.
1cy fuscus in August, ringed in Finland. (81365 bytes)L. f. fuscus 4cy CAU2 March 13 2010, Ashdod, Israel. Picture: Amir Ben Dov. Also seen as 3cy in Finland.
1cy fuscus in August, ringed in Finland. (81365 bytes)L. f. fuscus sub-adult CYY4 March 26 2010, Ashdod, Israel. Picture: Amir Ben Dov.
1cy fuscus in August, ringed in Finland. (81365 bytes)L. f. fuscus 4cy U0JD 2010-2012, Ashdod, Israel. Picture: Amir Ben Dov. Bird seen many times between March 2010 - March 2013. Some look-alikes added as well.
1cy fuscus in August, ringed in Finland. (81365 bytes)L. f. fuscus sub-adult March 26 2010, Ashdod, Israel. Picture: Amir Ben Dov. With heuglini.
1cy fuscus in August, ringed in Finland. (81365 bytes)L. f. fuscus sub-adult March 26 2010, Ashdod, Israel. Picture: Amir Ben Dov. Moult division at P6 suggests 3cy?
1cy fuscus in August, ringed in Finland. (81365 bytes)L. f. fuscus sub-adult March 25 2013, Ashdod, Israel. Picture: Amir Ben Dov.
1cy fuscus in August, ringed in Finland. (81365 bytes)L. f. fuscus sub-adult March 25 2013, Ashdod, Israel. Picture: Amir Ben Dov.
1cy fuscus in August, ringed in Finland. (81365 bytes)L. f. fuscus sub-adult March 28 2013, Ashdod, Israel. Picture: Amir Ben Dov.
1cy fuscus in August, ringed in Finland. (81365 bytes)L. f. fuscus sub-adult March 25 2011, Ashdod, Israel. Picture: Amir Ben Dov.
1cy fuscus in August, ringed in Finland. (81365 bytes)L. f. fuscus sub-adult March 25 2011, Ashdod, Israel. Picture: Amir Ben Dov.
1cy fuscus in August, ringed in Finland. (81365 bytes)L. f. fuscus sub-adult March 25 2013, Ashdod, Israel. Picture: Amir Ben Dov.
1cy fuscus in August, ringed in Finland. (81365 bytes)L. f. fuscus sub-adult March 25 2013, Ashdod, Israel. Picture: Amir Ben Dov.
1cy fuscus in August, ringed in Finland. (81365 bytes)L. f. fuscus sub-adult, March 29 2014, Ashdod, Israel. Picture: Amir Ben Dov.
1cy fuscus in August, ringed in Finland. (81365 bytes)L. f. fuscus sub-adult March 26 2013, Ashdod, Israel. Picture: Amir Ben Dov.
1cy fuscus in August, ringed in Finland. (81365 bytes)L. f. fuscus sub-adult March 26 2013, Ashdod, Israel. Picture: Amir Ben Dov.