Brown-hooded Gull
Chroicocephalus maculipennis
Adults in the breeding season have a dark brown head and throat with a white semicircle around the posterior of the eye, while the neck, chest and abdomen are white. In winter plumage, the brown hood is largely lost, retaining just a dark spot behind the eye and a dark smudge around the eye. The beak and legs are red, and the eye is dark brown. The outer primary flight feathers are white with black tips (the 'spots' of the scientific name) above and showing more extensively black from below, while the inner primaries and the secondaries and covert feathers are a silvery grey.
ID text from Wikipedia, CC BY-SA 4.0
Grey-headed Gull
Chroicocephalus cirrocephalus
The grey-headed gull is slightly larger than the black-headed gull at 42 cm length. The summer adult has a pale grey head, a grey body, slightly darker in tone than in black-headed gull, and red bill and legs. The black tips to the primary wing feathers have conspicuous white "mirrors". The underwing is dark grey with black wingtips. The grey hood is lost in winter, leaving just two dark smudges around and behind the eye. The eye is dark in immatures, but has a white iris in adults. The sexes are similar.
ID text from Wikipedia, CC BY-SA 4.0
Where you might meet both
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