Images of Yellow-legged Gulls Larus michahellis and of gulls of other species but also with yellow legs.
All images were taken at the sand suppletion activities on the beach of Katwijk aan Zee, The Netherlands, 19 – 20 October 2013.
Yellow-legged Gulls
Bird #1
First-calendar year, fitted with a ring from Switzerland. No new wing coverts are visible yet.
Katwijk aan Zee, The Netherlands, 19 October 2013.
Bird #2
Dark individual with still some juvenile scapulars and no replaced wing coverts.
Katwijk aan Zee, The Netherlands, 19 October 2013.
Bird #3
Small individual (possibly female) with contrasting scapulars and no second-generation wing coverts yet.
Katwijk aan Zee, The Netherlands, 20 October 2013.
Bird #4
Fourth-calendar year individual, aged by the presence of black in the primary coverts.
Katwijk aan Zee, The Netherlands, 20 October 2013.
Katwijk aan Zee, The Netherlands, 20 October 2013.
Katwijk aan Zee, The Netherlands, 20 October 2013.
Fourth-calendar year type Yellow-legged Gull (left) with adult Herring Gull (right). Katwijk aan Zee, The Netherlands, 20 October 2013.
Bird #5
Sixth-year old individual, ringed in The Netherlands as Blue DB.
Yellow-legged Gull Blue DB (center) with adult European Herring Gull (back). Katwijk aan Zee, The Netherlands, 20 October 2013.
Blue DB, looking conspicuous with its bright yellow legs. Katwijk aan Zee, The Netherlands, 20 October 2013.
Katwijk aan Zee, The Netherlands, 20 October 2013.
Katwijk aan Zee, The Netherlands, 20 October 2013.
I have seen Blue DB on several occasions during the last couple of years, for more images see my Flickr page
Scandinavian Herring Gull
Adult Scandinavian Herring Gull Larus argentatus argentatus, identified based on its slightly larger size compared to local European Herring Gulls Larus argentatus argenteus, dull-yellow legs, extensive streaking on the head and in the neck, the dark-orange to red orbital ring, large mirrors on P9 and P10, and lack of black in the outer webs of the outer primaries.
Katwijk aan Zee, The Netherlands, 20 October 2013.
Scandinavian Herring gull between smaller sized and pink-legged European Herring Gulls. Katwijk aan Zee, The Netherlands, 20 October 2013.
Katwijk aan Zee, The Netherlands, 20 October 2013.
Katwijk aan Zee, The Netherlands, 20 October 2013.
Caspian Gull
Adult female, a strikingly small bird with dull yellow legs.
Katwijk aan Zee, The Netherlands, 20 October 2013.
Katwijk aan Zee, The Netherlands, 20 October 2013.
Katwijk aan Zee, The Netherlands, 20 October 2013.
Katwijk aan Zee, The Netherlands, 20 October 2013.
Gulls to the Horizon 
Hey Maarten, have you seen this yet? Apparently, some people in your country tracked a gull with GPS over the course of a single day and then made a nice animation.
http://io9.com/gps-tracking-reveals-a-day-in-the-life-of-a-seagull-1451819141
Yes, this project is undertaken in a gull colony that I regularly visit. See http://www.flickr.com/search/?w=42852779@N04&q=gps.
For some of the results of the project, see https://gullstothehorizon.wordpress.com/2013/06/17/a-must-read-thesis-on-the-breeding-and-foraging-behavior-of-dutch-large-gulls/
Oh yes, I remember looking through that now – and I was asking you about how you stop a gull from going crazy if you put a GPS transmitter on its back.
This gull travelled a lot further in a single day than I expected. I always thought that gulls tended to hang around and forage roughly in the same area all day – and I suppose that some of them do, depending on the circumstances.
I found it quite interesting that she seemed to be scavenging in urban areas first, before heading out to sea to presumably obtain fish. I do remember hearing that gulls will typically try to avoid feeding garbage to their chicks. That was my immediate thought last night – that she was first feeding herself and then collecting higher-quality fresh food to take back to her young…