Made a short gif for y'all, thanks again
Obvious answer: Young seagull. Young gulls are relatively brown compared to adults and it takes most species 3 or 4 years to grow in all their adult feathers and have their beaks, legs, and sometimes eyes change color.
Probably a Lesser Black-backed Gull. They're super common in northern Europe, it's paler overall than most young gulls, and the shape of the head, bill, and body seem to fit that species better than other gulls. That said, young gulls are really goddamn hard to identify because they all look kind of like that.
Also, birds grow ridiculously fast compared to mammals. Just about every species that can fly has to be full size before they're capable of leaving the nest.
Normally I'd just ignore this, but I've taken a real dislike to you and your attitude, and I'm an autistic birder. So by the power of 10 seconds on Google, here's a bunch of things negating everything you've just said.
>aren't all that common here
"A familiar and abundant inhabitant of the European coastline"
"The Lesser Black-backed Gull breeds from the central-north of Russia, around Scandinavia, Germany, Belgium, the Netherlands and northern United Kingdom to Iceland"
"Medium to Large gull"
"medium-sized gull species"
>comparison to OP's gif
Average body length: 21 inches (53.34 centimeters)
Average body length of pigeons: 12 inches (30.48 centimeters)
From The Sibley Guide to Birds
Photo of a young Lesser Black-backed Gull that's super-similar to OP's pic:
Additional photos of young birds from lots of gull species that illustrate the differences in the shapes of their bodies, heads, and bills:
Thank you, come again.
gull related story.
>wonder why i only see black headed gulls in summer
>must be migratory
>must swap around with the usual gull i see the rest of the year
>talk to fellow /out/ friend, has made similar observation
>google black headed gull, mfw.
Black headed gulls are cute.
But a kitiwake is fine too
I wish I saw more of these guys but I hardly see them. They're the biggest gull and vicious bastards at that. They're more of a blood lusted eagle than anything.