Is this a Caspian gull? Ireland, North Coast (2 Viewers)

[leifvester]

Hey,

Photos taken from recordings on 13th Jan.

For context, I initially saw the bird in the flight photos and was trying to "age the Herring". The white bars on the greater coverts and the fine markings on the tail started to make me wonder if it could be a Caspian.

I started to look through other recordings from the same birding session.

I then came across the gull (attached) in profile and became instantly excited, and jumped to the conclusion that this was the same (Caspian) gull as was in flight.
The contrasting white and pear shaped head, strong gape, long tibia, apparent lack of checkered markings.

Now the doubt is seeping in. It seems highly unlikely to have Caspian gull on the North coast, and the body of the gull in profile is a little bit bulky, and the wing pattern may not be as unusual in Herring first-winter as I first thought.

 

[Alexander Stöhr]

Hello Leif,

I see where you are coming from, but I agree with you, its a 2cy Herring Gull imo.
Tertials seems to be too broad white edged (and can I see some tooth pattern?). All (yes) replaced 2nd generation scapulars have a good pattern for Herring Gull (but is it ok for a Herring Gull to have all replaced in january?) and jizz seems good for this too.

But yes, tail-pattern and bill shape might well be the result of some Caspian Gull genes. But proofing it, is another topic and more comments from experienced experts will surely say its within variation for a pure Herring Gull. (Thanks in advance!)

 

[GMS]

Herring Gull for me also. Lots of 2cy Herring Gulls now start showing quite pale/white heads. I think the replaced scaps at this time of year are not unusual for Herring Gull.

 

[leifvester]

Hey guys,

Appreciate the comments! I think the scapulars do look fine for Herring, and the primary projection looks fairly short.

Still the head of this bird is a real sticking point for me. I'm trying to get to Herring, but I just can't with that face haha.

Can a Herring gull head/face really look like this?
When I first seen this gull I immediately threw out Herring gull as a possibility because of the head shape / facial features. Perhaps that was brash given how variable gulls can be. Do you have any thoughts about the head?

 

[Evan Atkinson]

Hey guys,

Appreciate the comments! I think the scapulars do look fine for Herring, and the primary projection looks fairly short.

Still the head of this bird is a real sticking point for me. I'm trying to get to Herring, but I just can't with that face haha.

Can a Herring gull head/face really look like this?
When I first seen this gull I immediately threw out Herring gull as a possibility because of the head shape / facial features. Perhaps that was brash given how variable gulls can be. Do you have any thoughts about the head?

It's definitely a herring gull. The bill is too short for Casp and the greater coverts are chequered which implies that it's a herring as well. Greater coverts should be finely patterened in Caspian. TBF, the head is quite odd and I would have looked twice at it but as mentioned, there are various points that suggest it's not a Casp.

Evan

 

[leifvester]

Looking at the bird in flight, I can outline some additional hesitation I have.

See attached a photo of two Herring gull. A first winter in the bottom left, as indicated by the greater covert checkers, and a second winter in the top right as indicated by the barring on the greater coverts.

Compare with the bird in flight in the OP.
It clearly has no checkered markings on the greater coverts. Instead it has distinct white bars. Note as well the dark bill (not bi-coloured) and the lack of heavy pattern on the back and wings that is seen in this second winter Herring.
The tail is a contrasting white against black.

I believe the bird in flight in the OP is a first winter bird, which if so, cannot be a Herring gull based on the greater coverts.

Correct me if I'm wrong!

 

[leifvester]

Here's the video dowload link: Proton Drive

I should have included that earlier, sorry!

You can see it runs a little at the end which to my eye looks to be a longish stride.
Also appears to stand out so I'm not sure. Another weird gull walks past as well.

 

[Evan Atkinson]

Still a herring gull unfortunately. There are just too many things that cannot point towards Caspian gull that have been mentioned. The greater coverts are completely fine for a herring gull in my eyes. I am also slightly confused as to what gull we are now ID'ing because there are 3 different birds you have posted.

Evan

 

[leifvester]

Still a herring gull unfortunately. There are just too many things that cannot point towards Caspian gull that have been mentioned. The greater coverts are completely fine for a herring gull in my eyes. I am also slightly confused as to what gull we are now ID'ing because there are 3 different birds you have posted.

Evan

Thanks Evan, sorry I have a bad habit of posting too many different gull photos.

The problem is that I'm trying to link the gull in flight (OP) to a gull on the ground, because it was the initial reason why I was browsing through the video footage in the first place.
If I could lockdown that flying gull as Herring then it would actually make it a lot easier for me to accept the highly probable haha.

I think the greater coverts of the OP standing gull are the clincher as you already mentioned. I imagine that's the least variable characteristic.

Still I think I will spend some time doing some reading and sifting through images online. If I can find matching birds then I'll have a better grasp on the variation to watch out for, and it will release my mind from this gull

 

[leifvester]

So I've found this great post, and skimmed through the research paper:

• Larus cachinnans
• https://www.researchgate.net/public...lity_and_the_field_characteristics_of_hybrids

This approach is nice, because it tries to average out the variation, so you don't get too caught on any one feature.

I gave a go at scoring, and I'll explain my reasoning just incase I've got something wrong!
Points in square brackets.

1. Bill length/depth [2]: With low res images its difficult to measure with any certainty, but I was getting around 2.3/2.4 from some of the side profile images, which is at the upper end of Herring, but I did go for "intermediate". From a general observation, the bill looks slimish but moderate length.

2. Extend of scapular moult [0]: Despite the low quality images, all the scaps do look replaced.

3. Greater-covert pattern [2]: Definitely can see white markings, but didn't go for 3 as the other first-winter Argenteus present had a lot more white on the greater coverts.

4. Primary projection [2]: I was measuring around 0.45, although awkward to measure, sometimes it was around 0.5, but went for "medium" as that's also the impression.

5. Ventral bulge [0]: This one seems to be very subjective, however I can see a fair bit of bulge below the greater coverts and tail.

6. Tertial pattern: [2]: Of all the categories I think I understood this one the least. There does seem to be some pattern along the edge like Alexander mentioned, but I wouldn't it's heavily patterned.

7. Leg length [1]: Another subjective one. To me this bird had a stride instead of the waddle that many of the Herring present had. In the photos the tibia is noticeable. At the same time I wouldn't say the legs were very long, so I went for "moderately long".

8. Darkness of head/body [3]: More white than brown/grey. A lot more white than the surrounding first-winters. With that said the body is more brown than white.

9. Scapular pattern [4]: No plain feathers, all patterned.

10. Median covert moult [5]: All juvenile feathers

11. Greater covert moult [5]: All juvenile feathers

12. Tertial moult [3]: All juvenile feathers

---

Total score: 29

So from this score I can say with a high confidence: not a Caspian Gull.
The typically highest score for pure Caspian is 21.

Scores 22-25 indicate Hybrid.

Interestingly 29 was the lowest score for a first-winter Herring in their study, with 95% scoring 30+.
I think this just highlights the awkwardness of this particular bird.

As I've already been told repeatedly, I am content that this bird is a Herring gull

Cheers!

 

[lou salomon]

Such scoring often is a good way to get an accurate ID. Note however that, in gulls, certain weird individuals can fall outside the scoring. Your bird most certainly looks to be a 1c HG.

 

[Brian J Small]

The images you posted in the first post are not especially helpful, being sub-optimal in quality.

Not a Caspian, but the tail pattern is quite like that of Yellow-legged Gull, with a black band that narrows towards the outer tail feather - see Gull Research Organisation

In addition, though I may be seeing things that aren't there, there is the possibility of new 2nd gen coverts?

Brian

 

[leifvester]

The images you posted in the first post are not especially helpful, being sub-optimal in quality.

Not a Caspian, but the tail pattern is quite like that of Yellow-legged Gull, with a black band that narrows towards the outer tail feather - see Gull Research Organisation

In addition, though I may be seeing things that aren't there, there is the possibility of new 2nd gen coverts?

Brian

Hi Brian,

Thanks for the post!
Poor quality is unfortunate, but that's digiscoping at distance for you!

For the bird in flight, I didn't think the venetian pattern or pale window were good for Yellow-legged gull?