​On the morning of February 1st 2019 mainland Portugal was beginning to feel the effects of the depression "Helena". The day broke with showers and moderate SW wind. I decided to go to Peniche, one of my local patches, to take a look at seabird movement and check the gulls. To my pleasant surprise there was a Glaucous gull (Larus hyperboreus) resting among a group of Lesser black-backed gulls (Larus fuscus) and Yellow-legged Gulls (Larus michahellis), at the mouth of the Saint Domingos river.

Although I have observed this species several times in the past, particularly during the winter influx of 2013/2014, I had never observed this plumage. The bird, at first sight (and light conditions), had an adult appearance with a gray mantle and light iris, but with an immature bill. The bird was kind and allowed me to spend some time studying and photographing the plumage details.

The bird had a pale pink yellow bill, with a dark, relatively well-marked, subterminal stripe. The tip was ivory. The legs were pink, more intense than the beak. The iris was pale olive and had a dark pre-ocular mark. Note the pale brown infusions on the side of the chest, extending to the nape.

The third left tail feather (R3) presented a slight brown infusion along the shaft.

The coloration of the primaries begins to approach the adult pattern, however, it presents with a less obvious division between the white of the feather tip and the interior.

A good portion of the innermost greater and median coverts, as well as the  tertials,  were white.

In flight we can observe the marbled pattern formed by the contrast between the white and buffish coverts and the gray.

The underwing coverts presented creamy tones in the median and lesser coverts, forming a slight brownish bar, which contrasted with the white axillaries.