Monday, 4 February 2013

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. 

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