Sunday 26 September 2010

Common Gull (Larus canus): 2cy plumage variation in February in Norway

In February 2010 I had the opportunity to spend a few days in Stavanger, Norway and the most promising gull spot was the partly frozen lake at Breidavatn in central city. A large number of Common Gulls were seen on each visit and their variability in moult progression was striking.

The plumage variation in Stavanger was surprising seen from a Danish point of view as we only occasionally find Common Gulls with retained juvenile mantel and scapulars in late winter.

In Denmark most individuals have completed their first winter moult by February whereas gulls that had retained an extensive amount of juvenile upperpart coverts seemed predominant among the Stavanger gulls, with some even being in complete juvenile plumage. Such “retarded” individuals either belong to northern late breeding populations or they might be eastern ssp. heinei.

Features that suite ssp. heinei in few of the individuals are without being diagnostic:

1) long-winged appearance where the very long and slender wings are held slightly dropped on standing gull. On folded wing p5 is obviously exposed behind the longest tertials in a degree rarely mirrored by any canus and p10 is the longest primary
2) retarded moult in February with massive presence of juvenile upperpart feathers which is only seen on northern canus breeders
3) heavy markings and barring on hind neck, breast and along flanks where canus often has finer markings and a more striated patterns without the washed out appearance of some of these gulls
4) less marked underwing coverts than in canus
5) more contrast in upper wing than on typical canus with lesser upperwing coverts darker brown than in canus and greater upperwing coverts darker brownish-tinged with weak dark subterminal spot and gradually darker towards outer coverts (most obvious in flight)

But when talking about ssp. heinei one has to acknowledge that such identification would be highly speculative without biometrics.

Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 3 photos (#01)




Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 2 photos (#02)






Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 4 photos (#03)



Common Gull (Larus canus), 2cy, 9.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#04)





Common Gull (Larus canus), 2cy, 9.2.2010, Breidavatn, Stavanger (Norway), 3 photos (#05)



Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 2 photos (#06)




Common Gull (Larus canus), 2cy, 9.2.2010, Breidavatn, Stavanger (Norway), 2 photos (#07)




Common Gull (Larus canus), 2cy, 11.2.2010, Breidavatn, Stavanger (Norway), 2 photos (#08)






Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 4 photos (#09)



Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#10)




Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 2 photos (#11)




Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 2 photos (#12)




Common Gull (Larus canus), 2cy, 9.2.2010, Breidavatn, Stavanger (Norway), 2 photos (#13)












Common Gull (Larus canus), 2cy, 11.2.2010, Breidavatn, Stavanger (Norway), 10 photos (#14)





Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 3 photos (#15)



Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#16)



Common Gull (Larus canus), 2cy, 9.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#17)



Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#18)





Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 3 photos (#19)



Common Gull (Larus canus), 2cy, 9.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#20)



Common Gull (Larus canus), 2cy, 9.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#21)



Common Gull (Larus canus), 2cy, 9.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#22)



Common Gull (Larus canus), 2cy, 9.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#23)



Common Gull (Larus canus), 2cy, 9.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#24)



Common Gull (Larus canus), 2cy, 9.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#25)




Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 2 photo (#26)



Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#27)



Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#28)



Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#29)



Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#30)



Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#31)



Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#32)



Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#33)



Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#34)



Common Gull (Larus canus), 2cy, 10.2.2010, Breidavatn, Stavanger (Norway), 1 photo (#35)




Common Gull (Larus canus), 2cy, 11.2.2010, Breidavatn, Stavanger (Norway), 2 photo (#36)