How to rule out American Herring gull? (2 Viewers)

[martyrynin]

Hey,

I saw this gull this morning, Ireland - North coast.

I'm basically certain that it is a European Herring gull, but I was wondering what the best way to solidify that is.

Is the underside of p10 being solid black the most diagnostic feature here?

There's no black on p5 which is really bad for AHG, but can still happen, in the same way that a European Herring gull can have an all black p9!

So I have identified the bird as European herring gull, I'm just wondering what is the best way to definitively (or close to certain) rule out AHG from these photos.

Thanks!

 

[pdwinter]

There's no black on p5 which is really bad for AHG, but can still happen, in the same way that a European Herring gull can have an all black p9!

I'm not sure what percentage of argenteus HGs lack a white mirror on P9 (5 birds in 200 lacked it in Barth's study of ssp argentatus) but here's one from two days ago.

No knowledge of American Herring Gull other than what's in the books I'm afraid.

 

[martyrynin]

I'm not sure what percentage of argenteus HGs lack a white mirror on P9 (5 birds in 200 lacked it in Barth's study of ssp argentatus) but here's one from two days ago.

No knowledge of American Herring Gull other than what's in the books I'm afraid.View attachment 1623044

Thanks Paul! Got the Cramp and Simmons book you suggested. They said 7% of Argenteus had no white spot, which is not rare by any means, and I have seen them before.

My bird looks very similar to that one for sure, the only slight difference is the black pattern on p6, which on my bird looks a bit better for American, but once again I'm not claiming that's what it is!

 

[pdwinter]

Thanks Paul! Got the Cramp and Simmons book you suggested. They said 7% of Argenteus had no white spot, which is not rare by any means, and I have seen them before.

My bird looks very similar to that one for sure, the only slight difference is the black pattern on p6, which on my bird looks a bit better for American, but once again I'm not claiming that's what it is!

I have the Cramp and Simmons book arriving today from the Oxfam shop - somewhat cheaper than when I bought the set new! I'm sure it will help my knowledge but no doubt my field identification skills with stay at their current level

Anyway back to your gull. I'm assuming it's a 4th winter bird from the brown markings on the coverts and (from what I've read) you would want to see some black marks on the tertials on a smithsonius at that age to add to the full set of ID features.

Maarten van Kleinwee gave me this reply in another forum
"There is a misconception within the gull community that European Herring Gulls do not have a full black band on P5, but we regularly see this in our (colour-ringed) individuals in our Dutch IJmuiden Forteiland colony (up to rare instances of a W-shaped band, similar to American Herring Gull)."
and gave this example to show how individual birds can change their primary pattern each year

Primary P5 pattern variation in Dutch Herring Gull YBUF over multiple seasons

Just for reference: images of the variation in the pattern of primary P5 of female Dutch Herring Gull Green YBUF, which we ringed as an adult in 2015 in the IJmuiden Forteiland colony, the Netherla…

gullstothehorizon.wordpress.com

Interesting stuff!

 

[martyrynin]

I have the Cramp and Simmons book arriving today from the Oxfam shop - somewhat cheaper than when I bought the set new! I'm sure it will help my knowledge but no doubt my field identification skills with stay at their current level

Anyway back to your gull. I'm assuming it's a 4th winter bird from the brown markings on the coverts and (from what I've read) you would want to see some black marks on the tertials on a smithsonius at that age to add to the full set of ID features.

Maarten van Kleinwee gave me this reply in another forum
"There is a misconception within the gull community that European Herring Gulls do not have a full black band on P5, but we regularly see this in our (colour-ringed) individuals in our Dutch IJmuiden Forteiland colony (up to rare instances of a W-shaped band, similar to American Herring Gull)."
and gave this example to show how individual birds can change their primary pattern each year

Primary P5 pattern variation in Dutch Herring Gull YBUF over multiple seasons

Just for reference: images of the variation in the pattern of primary P5 of female Dutch Herring Gull Green YBUF, which we ringed as an adult in 2015 in the IJmuiden Forteiland colony, the Netherla…

gullstothehorizon.wordpress.com

Interesting stuff!

Ah it's a 4th winter bird - that makes a lot sense now!
I must admit 5cy gulls are not typically on my radar.

rather similar to adult, but dark brown markings on primary coverts [sometimes restricted to dark shaft-streaks], tertials, wing-coverts and on both mandibles indicate this age; dark markings on upper mandible are often especially seen in older birds.

• Dark brown markings on primary coverts [x]
• Dark markings on upper mandible [x]

In addition, the Gulls of Europe book mentions that fourth-winter Herring will have restricted white mirrors. The heavy streaking on the neck may also be explained in part by the fact that 4th winter Herring finish their moult a month or two later than adults.