[VAGAbond]

When I see a gull like this I think Glaucous-winged.


Photo Winter Harbour late June

When I see one like below I think Herring based on dark wing tips. (Photo White Rock Nov.) But I am having doubts, firstly because there are quite few of these around the Lower Mainland and yet I see few reports of Herring Gulls on the various web sites. Secondly, the colouring on the neck appears mottled instead of striped. So what is it and what are the key features to observe? Are the dark wing tip a plumage stage of the Glaucous-winged gulls?



Thanks in advance.

[SCizzle]

According to my bird identification book (The Sibley Guide to Birds), Herring Gulls have black wing tips. I believe the gull in the second picture is a Glaucous-winged in nonbreeding plumage. Their nonbreeding period runs from September to March and you took the photo in November so that sounds about right. Let's see what others have to say.

[esle9]

I agree with SCizzle, that is a Glaucous-winged Gull. The key feature is that the wingtips are grey rather than black.
The darker-grey-than-usual wingtips could indicate some hybrid genes, Western x Glaucous-winged Gulls are very common in our area. They are so common that they have their own name "Olympic Gull" (not a real species). Pure Glaucous-wingeds like your first photo have the wingtips the same colour as the mantle, or just slightly darker. Hybrids are more charcoal grey. Also some gulls which look pure could have hybrid ancestry somewhere in their family tree.

Herring would have more pure black wingtips, like the darkness of a Ring-billed Gull. The mottled rather than streaked head plumage is a good indication of Glaucous-winged genes.
Herring also have pale eyes.

[VAGAbond]

So is this one a herring gull? It has a light eye. Or is it a Thayer's Gull, round head?


Iona Sept.

[esle9]

Hmm… I'm not sure about that one. The light eye and fairly heavy bill can rule out Thayer's. Dark wingtips rule out pure Glaucous-winged.
While Glaucous-wingeds usually have dark eyes, some do have pale eyes, so pale eyes aren't always diagnostic for Herring. I think the wingtips are a shade too light and the bill a bit too heavy for Herring, I would go with Glaucous-winged x Western hybrid. The head streaking also looks smudgy like a Glaucous-winged rather than streaked like a Herring. I'm not positive though.

[miketabak]

Vagabonds Iona gull is an adult Thayer's Gull. Herring gulls have black wingtips. Some Thayer's Gulls have pale eyes. Thayer's Gulls have much less dark colour in the primaries than Herring Gulls.

If you want to see some Thayer's Gulls there have been 6 or more at Iona in the SW pond for more than a month now. Best place to learn gulls is in the field with a scope and bird fieldguide.

[russellcannings]

Just to build on blackcappedlory's comments (As I too think this is a Thayer's Gull):

I don't think any pure Glaucous-wings have pale eyes but perhaps in very rare cases they do. Some hybrid Glaucous-winged x Westerns certainly do although their irises are usually more of a dark green colour--not as pale as the bird pictured. Furthermore, those hybrids tend to have a lot more Western Gull genes and so would typically have a darker mantle than this bird.

When assessing a single gull with nothing to compare it too, relative size and shape can be tricky (not to mention the impact of lighting). If this bird was observed in the field, one would probably note it's relatively small size compared to the majority of Glaucous-wings present. I can definitely see where Else is coming from in that sense. Perhaps the bill appears stockier than a Herring because it is relatively short. To me the head is relatively rounded and small compared to Glaucous-winged/hybrids/Herring, and the bill is relative to that headsize as well. The pale eye is typical of about 10% of adult Thayer's Gulls in BC.

Lastly, Thayer's Gulls can be fairly variable in their outer primary patterning--from jet black to pale grey. This bird is probably right in the middle; apparently showing ashy-black primaries with prominent white tips. These white tips are usually relatively broader than Herring, and they also usually show broader pale edges to the edges or "inner webbing" of the outer primaries. This feature helps to separate them from Herring even when they have jet-black primaries. It may seem obscure but with practices you'll find you almost subconsciously notice these differences as you scan through a gull flock.

In addition to a scope and field-guide, I would also recommend making friends with someone who knows local gulls fairly well, as fieldguides can often be misleading of key features, and virtually never show all the variations in plumages, especially up here in the Pacific NW when we have all these mutts lurking about!

The next best thing is posting on groups like this (online), then try and apply knowledge gained in the field.

Cheers,

Russ Cannings
Nanaimo, BC