Possible Caspian Gull x Herring Gull hybrid

This could be a pure cachinnans and even though one may argue that most of the features seen in this bird also fit argentatus, there are firm clues that at least one of the parents must have been a cachinnans. Even though the upperparts are rather pale; head relatively large and striated; and p10 lack white mirror, it would not surprise me if it still fits within the phenotypic variation found in true cachinnans. However, a hybrid or backcross is not easy to rule out and on current knowledge this may even seem like the most probable solution. See other comments on Gull Research.

Photoes were taken on February 2, 2013 at Vejers Strand in West Jutland.

Russian Common Gull (Larus canus heinei), 2cy, 16.1.2013, Svanemøllebugten, Copenhagen

It is the upper left individual. Note that it is taller, but also stronger and heavier than the average canus in direct comparison. Note the heavy breast and beer belly...

On January 16, 2013 I photographed this large heinei Common Gull in Copenhagen. Together with Kjeld Tommy Pedersen I was out feeding gulls and it was immediately striking mostly due to its long wings, large size and heavy structure compared to the nearby canus. Due to its long legs, pushed up breast, slender and elongated structure and long bill, there was almost a cachinnans jizz to it. It was obviously much taller and structurally different from all the canus.

Luckily, Kjeld caught and ringed the same bird a few days later on January 22, 2013 which allowed for the needed measures to confirm the identification. It had a total head length of 100.6 mm and the folded wing was 395 mm – thus clearly a heinei on wing length (max wing in canus 390mm). According to Kjeld one should actually add 7-10 mm to the wing measure because it is a 2cy individual and they grow even longer with age. It was really a long winged and large individual.

It was ringed with metal AC 5558 and yellow colour ring with the inscription K9J.

It is the left of the two individuals seen from behind. Note the thicker and longer legs.

Note the densly dark-patterned hindneck, creating solid dark necklace.

Retarded moult in February with massive presence of juvenile feathers in upperparts is a classic heinei feature; however, it can also occure in late breeding canus from northern populations.

The bill is heavier and more parallel-edged relative to canus in direct comparison.

It was a large bird...

Note the relatively broad tail band and how the black on especially the outer feathers creates bayonets. On some Common Gulls wintering in Japan, the black tail band is wide enough to reach the edge of the uppertail coverts. Photo: Kjeld Tommy Pedersen.

Herring Gull (Larus argentatus) with pale plumage and leucisme

A rather pale 2cy argentatus Herring Gull which recalls some birds labeled as hybrid hyperboreus x argentatus (Viking Gull). Compared to normal-looking Herring Gulls it has paler primaries with some reduction in dark pigmentation, especially in the outer primaries, paler tail band and heavily vermiculated inner half of the tail, and more barred tertials, less black along the feather shaft in the scapulars, fainter facial mask and often paler base to the bill. All these features point towards some influence from Glaucous Gull genes and some people argue that this kind of phenotypic variation result from introgression of Glaucous Gull genes, at present or in the past, along the northern parts of the Herring Gull range. However, as we also see such extreme individuals with extensive white coloration among local breeding birds in Denmark one could also argue that these are only pale extremes of the variation within the nominate argentatus subspecies of Herring Gull. It was photographed on January 16, 2013 at Fiskerihavn Copenhagen. 

Herring Gull (Larus argentatus) with extensive white coloration

A rather pale 2cy argentatus Herring Gull which slightly recalls some birds labeled as hybrid hyperboreus x argentatus (Viking Gull). Compared to normal-looking Herring Gulls it has paler tail band and very much white as well, recalling marinus, more barred tertials, less black along the feather shaft in the scapulars and fainter facial mask. All these features point towards some influence from Glaucous Gull genes and some people argue that this kind of phenotypic variation result from introgression of Glaucous Gull genes, at present or in the past, along the northern parts of the Herring Gull range. However, as we also see such extreme individuals with extensive white coloration among local breeding birds in Denmark one could also argue that these are only pale extremes of the variation within the argentatus subspecies of Herring Gull. It was photographed on January 16, 2013 at Fiskerihavn Copenhagen.

Note paler tertials and greater coverts compared to the normal argentatus Herring Gulls

In Finland there is a continuous sequence of Herring Gull plumages from the more common darker Herring Gulls to these pale Herring Gulls

Black-legged Kittiwake (Rissa tridactyla), ad, 1.4.2012, Hanstholm Harbour

This adult Black-legged Kittiwake was photographed in Hanstholm Harbour on April 1, 2012.