The Vega gull, East Siberian gull, or East Siberian herring gull (Larus vegae) is a large gull of the herring gull/lesser black-backed gull complex which breeds in Northeast Asia. Its classification is still controversial and uncertain. It is variously treated as a separate species, as a subspecies of the American herring gull (L. smithsonianus) or included with both the American herring gull and European herring gull in L. argentatus. The Mongolian gull, Larus mongolicus, has previously been regarded as a subspecies of the Caspian gull (L. cachinnans) but is now sometimes lumped with the Vega gull.
he Vega gull is similar to the herring gull but is slightly darker grey above. The head of the Vega gull is heavily streaked with brown in winter, especially on the back and sides of the neck forming a collar. The legs are usually bright pink. First- and second-winter Vega gulls are darker than the similar Mongolian gull, notably on the crown of the head where Mongolian gulls even in first- and second-winter are a bit paler. Almost the full body of first- and second-winter Vega gulls displays darker brown flecks and streaks. Adult Vega gulls in winter can often be mistaken for the very similar-looking slaty-backed gull (L. schistisagus) and the western gull (L. occidentalis), but the Vega gull's gray is lighter than the two similar species. Eye colour is variable but tends to be dark with a red orbital ring. The bill is yellow with a red spot except for first- and second-winter gulls where the bill can be almost entirely dark gray/black, with the gray portion shrinking until it reaches maturity.
Vega gulls in the northwestern part of their breeding range are paler above. They are sometimes considered to be a separate subspecies named Birula's gull (Larus vegae birulai).