Putative 4cy Caspian Gull

[Tristan R]

Hi,

I took the attached images yesterday (8th March) at Strathclyde Loch. I am fairly happy that it is a 4cy Caspian Gull. However having slipped up with this species before I would appreciate any opinions on this bird.

Regards
Tristan Reid

[Josh Jones]

Tristan,

Saw this being discussed on BF although as a BF reject I can only post on here.

Let's start with the mantle - quite pale; a bit too pale for a cachinnans, and more akin to argenteus Herring. Primary projection is short, and the bird on the whole has a structure that suits Herring better than Caspian.

The dark eye is interesting and certainly gives the bird a more Casp-like feel, although dark-eyed Herrings are not all that unusual. Although looking quite promising initially, the more you look at it the more you realise that, facially, the bird is not quite 'right' - I don't think head structure is right either. Having said that I would certainly give it a second look if I had seen it!

Note than the bird's bill is thick (and not particularly long), with a strong-looking gonydeal angle. Its colouration is also notably bright - a bit too bright (in my opinion) for cachinnans of this age. It is hard to judge leg colour but they also seem to be quite pink.

To me, this is a Herring Gull (3w), one of those cachinnans impersonators that tend to turn up every now and again.

Have a look at this Caspian for comparison:

http://www.birdguides.com/pictures/default.asp?v=1&f=162667&r=0&st=0&q=

Cheers
Josh

[Tristan R]

Tristan,

Saw this being discussed on BF although as a BF reject I can only post on here.

Let's start with the mantle - quite pale; a bit too pale for a cachinnans, and more akin to argenteus Herring. Primary projection is short, and the bird on the whole has a structure that suits Herring better than Caspian.

The dark eye is interesting and certainly gives the bird a more Casp-like feel, although dark-eyed Herrings are not all that unusual. Although looking quite promising initially, the more you look at it the more you realise that, facially, the bird is not quite 'right' - I don't think head structure is right either. Having said that I would certainly give it a second look if I had seen it!

Note than the bird's bill is thick (and not particularly long), with a strong-looking gonydeal angle. Its colouration is also notably bright - a bit too bright (in my opinion) for cachinnans of this age. It is hard to judge leg colour but they also seem to be quite pink.

To me, this is a Herring Gull (3w), one of those cachinnans impersonators that tend to turn up every now and again.

Have a look at this Caspian for comparison:

http://www.birdguides.com/pictures/default.asp?v=1&f=162667&r=0&st=0&q=

Cheers
Josh

Hi Josh,

Thanks for your response. My experience of Caspian Gull is limited to just a handful of individuals.
I would say that in the field the mantle colour did appear darker than a typical argenteus - the photos I took were shot into bright sunlight, so perhaps the mantle tone in the images is slightly washed out. The bird was very long-legged with a greater length below the knee that I have ever seen in any argenteus (or argentatus for that matter). They did not appear particularly chunky. The leg colour was diificult to judge, but did appear grey/pink in the field. My main concern with this bird was the bill length and gonys angle.

I have attached another series of images for interest.

Regards
Tristan

[Josh Jones]

Tristan - nice shots here. It seems to be one of those birds that is almost, but not quite, Caspian. Although a couple of your images do show it look quite Caspian-like, others reveal the large size of the eye and structure amongst other things that I mentioned in my previous post, that point towards Herring and are at odds with Caspian.

Can certainly see why it caught your eye, a very distinctive bird!

Out of interest, I suspect Caspian Gull is a rare bird in Clyde?

[Tristan R]

Out of interest, I suspect Caspian Gull is a rare bird in Clyde?

Yes, a rare bird in Scotland generally (hence my caution)!

[Josh Jones]

Yes, a rare bird in Scotland generally (hence my caution)!

No surprise there I guess!

Your newest batch of images are more convincing when talking Caspian, but it still isn't quite there. Mantle is too pale, the eye is large, and bill and head shape just don't do it for me. Jan's links on BF to netfugl were quite good in illustrating how Herrings can look deceptively like Caspian. Some Herrings retain their dark eyes as his links prove (especially immature birds).

Some Herrings can seem long-legged.. equally some Caspians can be quite short-legged. Also not particularly convinced about the primaries from the open wing shot (lack of mirror on P10!). The mantle is again much too pale for michahellis so thats out the equation as well.

The photo Craig posted on BF, for me, is one of the key photos for drawing a conclusion. So, I'll stick with one of those odd-looking Herring Gulls. I've seem fairly similar birds before on the tips in Peterborough (although not quite as convincing as this one), but never really paid a huge amount of attention... interesting birds though!

Cheers
Josh

[Brian S]

Josh has dealt with this very well, and I agree with all but one thing he has written, though I would like to comment on his statement on bill colour. There have been at least four 3cy (2w/2s) Caspians coming into Minsmere recently (3 this morning); one has a very advanced bill coloration akin to 3w/3s - very yellow, with a subterminal red spot and narrow black line across. I will try to add a videograb later.

Just added pic to scarce bird gallery

Brian S

[Tristan R]

Josh has dealt with this very well, and I agree with all but one thing he has written, though I would like to comment on his statement on bill colour. There have been at least four 3cy (2w/2s) Caspians coming into Minsmere recently (3 this morning); one has a very advanced bill coloration akin to 3w/3s - very yellow, with a subterminal red spot and narrow black line across. I will try to add a videograb later.

Just added pic to scarce bird gallery

Brian S

Hi Brian,

Thanks for your comments. This bird is certainly confusing, and has pretty much thrown all what I though I knew about Caspian Gull ID out the window! I saw your Caspian Gull image on the scarce bird page. Is the gonydeal angle shown on your bird on the steeper end of the scale for this species?

Regards
Tristan

[Tristan R]

Hi,

I am not sure if this will add anything to the discussion, but have added some images of the same bird taken by Craig Shaw from a different angle.

Regards
Tristan

[Josh Jones]

These new images show just how pale the mantle is (fine for argenteus, not for cachinnans), how the structure is more suited to Herring rather than Caspian Gull, and how deceptive this bird can look in some photos!

In at least two photos, the head seems really Casp-like, but the last one less so. Just one of those Herrings with Caspian-like faces.

Have a look at these superb birds to compare and contrast. Not necessarily the same age, but it is worth noting mantle colour in these birds as well as head shape etc:

http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=13775

http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=14953

http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=15396

and then look at your bird:

http://www.surfbirds.com/forum/attachment.php?attachmentid=472&d=1205080644

http://www.surfbirds.com/forum/attachment.php?attachmentid=476&d=1205090987

[Tristan R]

These new images show just how pale the mantle is (fine for argenteus, not for cachinnans), how the structure is more suited to Herring rather than Caspian Gull, and how deceptive this bird can look in some photos!

In at least two photos, the head seems really Casp-like, but the last one less so. Just one of those Herrings with Caspian-like faces.

Have a look at these superb birds to compare and contrast. Not necessarily the same age, but it is worth noting mantle colour in these birds as well as head shape etc:

http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=13775

http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=14953

http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=15396

and then look at your bird:

http://www.surfbirds.com/forum/attachment.php?attachmentid=472&d=1205080644

http://www.surfbirds.com/forum/attachment.php?attachmentid=476&d=1205090987

Hi Josh,

Thanks for the links. I am still not convinced about the mantle colour being an issue with this bird. As in the field it appeared darker. Looking on the net, structure of cachinnans seems to vary almost as much as argenteus! I think this bird will be left unidentified!

Regards
Tristan

[Josh Jones]

I am still not convinced about the mantle colour being an issue with this bird. As in the field it appeared darker. Looking on the net, structure of cachinnans seems to vary almost as much as argenteus! I think this bird will be left unidentified!

Still think its a Herring Gull. I guess we will never know what it is for sure(!) but there could possibly be some Caspian genes in there. Hard to say though as the only real feature that looks Caspian is the head and eye, and that seems to change depending on posture and angle. Certainly not a pure cachinnans anyway.

Gulls, got to love them!

[JanJ]

Hello Tristan.

I understand your feeling Tristan, gulls can be really frustrating!

Once again I´m not 100% convinced on either species Herring/Caspian, but I´m more on the Herring side despite some of the Caspian features shown by your gull.
Still these day´s - approx. out of 10 Caspians - 7-8 are straightforward while 2-3 are more difficult and needs to be scrutinised.

This one from Denmark signals Caspian at first sight but is clearly a Herring Gull on structure and bill shape. Note that p5 (partly hidden under the tertials) has black markings, but we can´t see if this mark is restricted to outer web - or both webs.

http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=5472

And what about this one:

http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=5399

This one is clearly a Herring Gull despite the small darkish eye and leg colour, but structure, shortish bill and primary pattern - on both wings suggest a Herring.

http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=10607

Check some of the Herrings here, the Caspian like bill in the third image, the dark eyed in image 8:

http://www.tarsiger.com/gallery/index.php?p=pics&sp=search&lang=eng&species=16120&family=&sex=0&age=0&country=&manner=&year=&photo=&pic_method=0&pic_type=0&place=&order=lisays_paiva+DESC&sel=2&find=find&r=3

and the last one here:

http://www.elisanet.fi/antero.lindholm/public_html/lokki/arg4kv.htm

Another:

http://www.pbase.com/slisch/image/88852719

JanJ

[Tristan R]

Still think its a Herring Gull. I guess we will never know what it is for sure(!) but there could possibly be some Caspian genes in there. Hard to say though as the only real feature that looks Caspian is the head and eye, and that seems to change depending on posture and angle. Certainly not a pure cachinnans anyway.

Gulls, got to love them!

I think you are probably right Josh. I would certainly not want to claim this as a Caspian Gull. On the other side of the coin, if this bird was in an area where Herring Gull was very scarce I would not want to claim it as one of them either!

Is there any evidence that these 'Caspian type' Herring Gulls are Herring Gulls or is this the safest bet scenario?

You have got to love gulls, they get you thinking that for sure! I have learned huge amounts from this bird and the communications I have had about it both on forums and privately.

Regards
Tristan

[Tristan R]

Hello Tristan.

I understand your feeling Tristan, gulls can be really frustrating!

Once again I´m not 100% convinced on either species Herring/Caspian, but I´m more on the Herring side despite some of the Caspian features shown by your gull.
Still these day´s - approx. out of 10 Caspians - 7-8 are straightforward while 2-3 are more difficult and needs to be scrutinised.

This one from Denmark signals Caspian at first sight but is clearly a Herring Gull on structure and bill shape. Note that p5 (partly hidden under the tertials) has black markings, but we can´t see if this mark is restricted to outer web - or both webs.

http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=5472

And what about this one:

http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=5399

This one is clearly a Herring Gull despite the small darkish eye and leg colour, but structure, shortish bill and primary pattern - on both wings suggest a Herring.

http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=10607

Check some of the Herrings here, the Caspian like bill in the third image, the dark eyed in image 8:

http://www.tarsiger.com/gallery/index.php?p=pics&sp=search&lang=eng&species=16120&family=&sex=0&age=0&country=&manner=&year=&photo=&pic_method=0&pic_type=0&place=&order=lisays_paiva+DESC&sel=2&find=find&r=3

and the last one here:

http://www.elisanet.fi/antero.lindholm/public_html/lokki/arg4kv.htm

Another:

http://www.pbase.com/slisch/image/88852719

JanJ

Thanks JanJ - Some excellent links.

Certainly a steep leaning curve for me!

In the words of Big Chris 'Its been emotional' :lovegulls::lovegulls: