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

(last update: 30-12-2009)

Larus fuscus male 4+cy JM93 June 24 2002, Nordfugløy, Troms, Norway. Pictures: Morten Helberg.

The upper-part grey tone in JM93 seems to be intermediate between pale-mantled birds and fuscus-type birds. Interestingly, the migration route seems to be intermediate as well! Complete moult still not started by late June. Here, you also see a map of Europe, with the ring readings for JM93.

The most northern island in the county Troms is Nordfugløy. Here you find a Lesser Black-backed Gull colony in cloudberry mires, about 300 meters above sea level. The oldest data about the presence of this colony are from 1963 when 125 pairs were estimated. Still, there was nothing known concerning the subspecies composition before the first adult birds were caught and colour-ringed in 2002. The breeding population varies a lot in numbers between the years, with a minimum of 15-20 pairs in 2002, and with a maximum of 100 pairs in 2006 and 2007. Nowadays, with about 100 pairs, it is the largest colony of Lesser Black-backed Gulls in northern Norway.

The island also hosts a breeding population of 100+ pairs of arctic skuas and 200+ pairs of Common Gulls. There is only one island in this ringing program which is higher up north: Loppa Island, which is a similar colony at about 200 meters above sea level.

The ringing program on Nordfugløy started in 2000, when juveniles were ringed. From 2000 to 2008, 172 juveniles were ringed here. Up to May 2008, 20 of these juveniles were seen outside the breeding range. Between 2002 and 2007, 17 adults were ringed as well, with 7 rediscoveries. This is a remarkable high recovery rate, certainly due to the predominant western migration route chosen by the adults breeding on this island. Pale-mantled birds from Nordfugløy have been rediscovered in Portugal, Spain, Italy and Libya. One dark fuscus-type bird has been observed frequently in Israel.

More information about migration strategies in Norwegian fuscus and the ringing programme in the three northern counties of Norway: Nordland, Troms and Finnmark, can be found here: The summary for juveniles can be found in the fuscus 1cy October section, the summary for adults can be found in the fuscus adult October section.
Morten Helberg, Geir Systad, Ingve Birkeland, Nils Lorentzen & Jan Bustnes published an article about this research in Ardea 97, 2009, titled: Migration patterns of adult and juvenile Lesser Black-backed Gulls Larus fuscus from northern Norway. The complete PDF can be found HERE.

below: JM93 Ring readings. Picture: Morten Helberg.

The ringing research is described in fuscus adult March section and fuscus adult October section. All resights up to May 2008 are included in this research, in the three northern counties of Norway. Colonies could either consist of pure fuscus birds, or colonies could show mixed breeding birds, both pale-mantled birds and fuscus types. Adults were trapped during the incubation period in late June, using walk-in cages. In mixed colonies with pale and dark-mantled birds, sub-species were determined easily in the hand. 199 birds were caught: 172 fuscus, 22 pale-mantled birds and just 5 birds undetermined.
Between 2000-2007, 16 birds (8%) were resighted. 10 pale-mantled birds (10/22 = 45%) and only 6 fuscus (6/172= 3,5%) were seen outside the colonies. When considering only mixed colonies, the figures don't change much; resighting probablities for fuscus remain low.
Several birds confirmed the idea of fuscus being an eastern migrant: single observations from central inland Norway, the Baltic Sea and Israel demonstrate the eastern migration route (eastern flyway through Finland, Black Sea, Israel to the Rift Valley into the African Great Lakes). However, there were observations of fuscus in England, and later that winter this bird turned up in Morocco and another bird in Portugal.
Pale-mantled birds were found in England, 3 on the Iberian Peninsula, and single birds in Morocco, Belgium, Italy and Libya. These represent the western migrants.