White-winged gull, Canada (eBird link) (1 Viewer)

[Peter C.]

Hi,

I've never tried this before, so I hope it works. The photos were from yesterday, March 20, in Waterloo, Ontario.

https://ebird.org/canada/view/checklist/S43821677

There's been some discussion over here (as there often is, with gulls) about the bird in the link. Would appreciate any input and justification for your choice.

 

[lou salomon]

1st cycle iceland gull is correct, most probably kumlieni since that 'taxon' is most likely in ontario, but not possible to exclude a nominate glaucoides from these pics. aynway, not a glaucous gull.

 

[Peter C.]

Thanks Lou,

I had it down as a good 1st-cycle Glaucous, because (a) the "tipping" on the wings and underparts seemed a lot light than depicted for L. g. kumlieni of that age, and (b) there is some pink at the base of the bill (more visible in scope view than in these photos). Does L. hyperborus invariably have a large pink basal half of the bill in 1st-cy?

One thing I DO see in one of the photos is, there's a fairly good length of primary extending past the tail - which I didn't notice in the field...

 

[njlarsen]

One thing I noticed was the shape of the head.

Niels

 

[Andrew Whitehouse]

Thanks Lou,

I had it down as a good 1st-cycle Glaucous, because (a) the "tipping" on the wings and underparts seemed a lot light than depicted for L. g. kumlieni of that age, and (b) there is some pink at the base of the bill (more visible in scope view than in these photos). Does L. hyperborus invariably have a large pink basal half of the bill in 1st-cy?

One thing I DO see in one of the photos is, there's a fairly good length of primary extending past the tail - which I didn't notice in the field...

I don't think a 1st winter (or any age) Glaucous would show as much black in the bill than this. To me this looks a pretty clear 1st winter Iceland/Kumlein's on structure and bill pattern.

 

[Peter C.]

Hi Niels, Andrew:

Thanks for your input. I thought I had these all sussed, but apparently not.

Niels, I've read somewhere - I think this was actually referring to separating L. g. thayeri from immature Herring Gull, rather than Glaucous - that the former has a "dove-like" head shape; is that the sort of thing you are referring to?

 

[njlarsen]

Hi Niels, Andrew:

Thanks for your input. I thought I had these all sussed, but apparently not.

Niels, I've read somewhere - I think this was actually referring to separating L. g. thayeri from immature Herring Gull, rather than Glaucous - that the former has a "dove-like" head shape; is that the sort of thing you are referring to?

I do not have my European bird books at the moment so cannot check, but I remember this as Glaucous having a head shape including an elongated slanting front similar to a Herring gull while white-winged has a head shape that is more rounded and thereby more similar to a common gull (Mew). The difference in size of bill supports these differences in head impression.

Niels