www.gull-research.org

While studying some pictures of juvenile lesser black backed gulls I encountered some birds which caused me a real headache. Of course yellow legged gulls start post juvenile moult earlier compared to most lesser black backed gulls, have paler inner primaries etc. but for some individuals I find it very hard to exclude a small female yellow legged gull with a retarded moult. I was wondering what would be the best way to approach the determination of such birds. Some pictures are exemplary given below (I hope I don't break any copy right or upset people by doing so)of birds which show one or more confusing characteristics: a very restricted amount of black on the outer retrices, paler inner primaries, light marked belly and head, a relatively strong bill, a less rich brown tone to the feathers, very pale leggs...


LBBG, Belgium august 23th (photo by Peter Adriaens)


LBBG, the Netherlands august 28th (photo by Theo Muusse)


LBBG, the Netherlands august 28th (photo by Theo Muusse)


LBBG, Belgium august 18th (photo by Charly Farinelle)

kind regards,

Jan

As for my photograph, I think it is always best to see and evaluate each bird on a series of photos, not just one. Gulls are difficult enough by themselves, so why make the identification process even harder by limiting the documentation ? It is often impossible to identify a large gull from just one photograph.
Here is the same bird from above:



Here, it can be seen that all scapulars are still juvenile and fresh, and that the tail pattern is not that unusual for a LBBG after all. Note also the extensively dark greater coverts.
But even in the other flight shot (from below), LBBG can be suspected because of the dark shins visible on the tarsi. Also, if you study the pattern of the undertail coverts, I think you will find that most juvenile michahellis show a more regular line of dark triangular spots there.

The two photos by Theo (both of the same bird) look more like michahellis to me, rather than LBBG.

Peter,

many thanks for the explanation, especially for the clue about the undertail pattern. I've probably overlooked that second image in your album.

adriaens wrote: The two photos by Theo (both of the same bird) look more like michahellis to me, rather than LBBG.

i thought the same, theo's photos show a bird with features strongly suggesting michahellis.

lou