dark "shins" on large gulls

[Martin Reid]

I have a question about a statement on the Gull Research Organization (GRO) website describing juvenile Azorean Yellow-legged Gull (YLGU): Near the bottom of the paragraph it says "Legs fleshy, many with darker spotting on upper tarsus and on feet (Dubois 2001) – a character unknown in other W Palaearctic gulls (but frequent in Kelp Gull)." Can anyone tell me if this statement is still considered to be accurate, or it if has been shown to be untrue?? It seems that the text for this entry on the GRO site is taken from " Malling Olsen, K. & Larsson, H. 2004 Gulls of Europe, Asia and North America. London: Christopher Helm" and thus is about ten years old... I think I recall seeing a statement or two that some LBBGs can have dark shins, a least early in their first calendar year - if correct, how long do they retain it? On a candidate Azorean YLGU from March, would the presence of dark shins and top-of-foot be in any way significant to its ID?

[lou bertalan]

quite strange - any western palearctic large gull taxon has dark shins as a juvenile, well caspian is said to have whitish ones but i found enough pics where they show dark ones. so i really don't understand this statement.

lou

[Martin Reid]

Thanks for your input Lou. I don't see dark shins on American HERGs in Texas, nor do I see them on photos of other taxa on the winter grounds... So how long do juvs of other species - for example Euro Herring Gulls - retain dark on their shins and on the top of their feet? Is it quickly lost, or can they retain it into the winter? I don't recall seeing any Euro or American HERGs with dark shins - ?

[lou bertalan]

are we maybe talking about different things? 3 american herring gulls with dark shins as i see them:

http://www.pbase.com/jpkln/image/148507668
http://3.bp.blogspot.com/_6mH3sGkGTeE/S ... G_3035.jpg
http://birdersplayground.co.uk/American ... enile.html

at least the shins are clearly darker than the pinkish legs.

looking through some european taxa (HG, LBBG, YLG, cach, GBBG) the dark shins become much paler by september but can appear as clearly darker than legs well through winter in some imdividuals. tendentially LBBG has darker shins than the others.

[Martin Reid]

Thanks for the links, Lou - I guess I don't start to do much gulling here in Texas until after the turn of the year, since the maximum counts for HERGs here is during the period late Feb through March. I note the three birds you've linked-to are juvs (or mostly juvs) and from early in the winter, and two of the three are from California. I wonder if dark shins are seen on east coast or Great Lakes birds, and how long the dark shins are retained by any of the North American populations.
What about Euro HERGs; is there a parallel situation, or are dark shins quickly lost by all taxa except Atlantic YLGU and to a lesser degree some LBBGs - ?
I'd really appreciate it if some of the GRO Gurus would chime in on this topic - thanks!

[adriaens]

Hi Martin,

the statement about dark shins in atlantis is not from Malling Olsen but from the Dubois paper (Birding World 14:7, 2001).
The exact wording (also posted at http://gull-research.org/atlantis/1cyoct.html) was:
"All the juveniles I checked on the Azores and on the Canary Islands showed extensive dark markings on the front of the tarsi and on the feet. ]uveniles and first-winters in Madeira apparently show a similar pattern (S. Nicolle, pers. com.). Nominate michahellis juveniles may show such dark markings less commonly, and they seem to be more quickly lost in other species such as Herring Gull and Lesser Black-backed Gull. Interestingly, this feature occurs on Kelp Gull L. dominicanus too (Higgins & Davies 1996)."
So Dubois's choice of words was actually quite cautious, but the subtle connotations seem to have been lost when we quickly tried to repeat and summarize this at http://gull-research.org/atlantis/1cysept.html,
leading to a very black and white statement that is simply wrong and that we have to change (Mars? Hello?).
So thanks for pointing it out.

I think we all know that pretty much all recently fledged juvenile large gulls may show dark shins.
It is true though that on average species like michahellis, European HG and American HG tend to lose them a bit more quickly than atlantis and Lesser Black-backed Gull,
but I doubt that anyone has seriously looked into this yet, and, in any case, it is certainly variable and does not appear to be the failsafe character that you may be looking for.
If you want to take 'herring gulls' as an example, the very first photograph of a 1st-cycle European HG on my website already shows a bird with distinctly dark shins, yet was taken in May (17 May 2009)!
https://plus.google.com/photos/11565979 ... 0435170210

In Newfoundland in late January, it was clear that quite a few 1c American Herring Gull still showed slight presence of dark shins, though fading.
See the photo below for an example.

It does not take much digging around to see that dark shins are quite normal in 1c Lesser Black-backed Gull throughout the winter.
There is at least one example of a bird from April on the GRO website:
http://gull-research.org/lbbg2cya/107kred.html

To put it this way, dark shins may be useful as an identification character if you are faced with a flock of 100 gulls of a single species and you only get to see the legs for some reason...
On a single bird, I doubt that it means much.

[Martin Reid]

Thanks Peter - this is just the kind of feedback I was looking for

For my part, I'll pay attention to this phenomenon ove rhere, and update the group if I discover anything significant.

[marsmuusse]

Dear friends,
This section about juvenile plumage is an exact copy from the book by Malling Olsen & Larsson. I therefore leave this piece text as it is, but I've added a note, to add the points you've mentioned in this topic. I also mention the wrong quotation of Dubois. Hope it makes sense to solve it this way?

Mars

For some fun: very freshly fledged juvenile L.a. argenteus with pale shins, together with fresh cachinnans with dark shins. Gull life is not complicated.