Glaucous-winged Gull x Glaucous Gull

 

Glaucous-winged Gull x Glaucous Gull hybrid, Port Townsend, Jefferson County (Washington, USA), 28th October 2011 - copyright Steve Mlodinow

(photo ID: 1371)

Steve points out that the head shape and small eye on this bird are suggestive of Glaucous Gull.  The primaries are intermediate, though perhaps more like Glaucous-winged Gull.  The pale base to the lower mandible would be abnormal for a pure juvenile Glaucous-winged Gull in October.  Steve notes that folded primaries this colour wouldn't be unusual in a Glaucous-winged Gull by mid winter.

Apparently the contrast between the folded primaries and the rest of the wing was more prominent in life than shown in the photo above, but it's more apparent in the blurry flight shots below.  The first flight shot isn't blurry though, and Steve highlights the intermediate wing pattern.  He points out that the apparent dark grey at base of secondaries is a shadow cast by the greater coverts which have been lifted up by the wind.

 Glaucous-winged Gull x Glaucous Gull hybrid (same bird as in photo ID 1371 above), Port Townsend, Jefferson County (Washington, USA), 28th October 2011 - copyright Steve Mlodinow

(photo IDs: 1372-1374)

The next bird is an adult and Steve noted that the wingtip pattern was intermediate between Glaucous-winged and Glaucous Gulls, the back and mantle were paler than Glaucous-winged Gull and the eye was dark.

Glaucous-winged Gull x Glaucous Gull hybrid, about 30 miles off Westport (Washington, USA), April 2008 - copyright Steve Mlodinow

(photo IDs: 1479-1480)

For the next one Steve notes that American Herring Gull x Glaucous-winged Gull should be darker on the wing-tips and would likely have a more obviously pale eye (this bird's is a bit brown) and bicoloured bill.

Glaucous-winged Gull x Glaucous Gull hybrid (the birds in the background are probably Western Gull x Glaucous-winged Gull hybrids), Mukilteo, Snohomish County (Washington, USA), 14th January 2011 - copyright Steve Mlodinow

(photo IDs: 1225-1226)

On the next bird Steve draws attention to the intermediate bill and primaries.  To its right is a bird that looks good for a pure adult Glaucous-winged Gull and behind it is a dark immature (partially in frame) that is likely a Western Gull x Glaucous-winged Gull hybrid.

Glaucous-winged Gull x Glaucous Gull hybrid, Cedar River Mouth, Renton, King County (Washington, USA), 30th December 2006 - copyright Steve Mlodinow

(photo ID: 1227)

Glaucous-winged Gull Larus glaucescens
Glaucous Gull Larus hyperboreus

Western Gull x Glaucous-winged Gull

Western Gull x Glaucous-winged Gull hybrid, Mukilteo, Snohomish County (Washington, USA), 31st January 2011 - copyright Steve Mlodinow

(photo ID: 1453)

There is an extensive overlap between the ranges of Western Gull and Glaucous-winged Gull and in that overlap zone (between southern British Columbia and southern Oregon) the two species readily hybridise.  Hybrids (known as Olympic Gulls) are not only fertile but in the centre of the zone they have superior fitness over pure birds.  Consequently there is a hybrid swarm of birds showing the full specturm of appearance between the two pure species.

For the bird at the top of this page Steve notes that the wingtips and back are too dark for pure Glaucous-winged Gull and not dark enough for Western Gull.  The bill is stout and the primaries short, which are unlike American Herring Gull x Glaucous-winged Gull hybrids which also typically have a paler mantle.

Steve points out that next bird is much like a first-cycle Western Gull, but the folded primaries are not dark enough and tipped pale.  Its bill is heavy for American Herring Gull x Glaucous-winged Gull hybrid, and the hint of a dark mask is suggestive of Western Gull heritage.

Western Gull x Glaucous-winged Gull hybrid, Everett, Snohomish County (Washington, USA), 25th January 2011 - copyright Steve Mlodinow

(photo ID: 1457)

Steve captured the same bird in flight, where he points out that you can see that the pale on inner webs of the primaries is too extensive for pure Western Gull. The wingtips are much too dark for Glaucous-winged Gull. American Herring Gull x Glaucous-winged Gull hybrid would usually have a more obvious pale panel on the inner primaries.

Western Gull x Glaucous-winged Gull hybrid (same bird as in photo ID 1457 above), Everett, Snohomish County (Washington, USA), 25th January 2011 - copyright Steve Mlodinow

(photo IDs: 1454-1456)

On the next bird Steve notes the dark mask of a Western Gull and the rather dark plumage overall with more Glaucous-winged Gull like primaries (but with primary tips still too dark for that species).

Western Gull x Glaucous-winged Gull hybrid, Elwha River Mouth, Clallam County (Washington, USA), 28th October 2011 - copyright Steve Mlodinow

(photo IDs: 1363-1364)

The next couple of birds are adults and Steve notes the intermediate wing pattern, and back colour more like Western Gull.

Western Gull x Glaucous-winged Gull hybrid, Elwha River Mouth, Clallam County (Washington, USA), 28th October 2011 - copyright Steve Mlodinow

(photo ID: 1360)

Western Gull x Glaucous-winged Gull hybrid, Elwha River Mouth, Clallam County (Washington, USA), 28th October 2011 - copyright Steve Mlodinow

(photo IDs: 1361-1362)

Here's another showing more etensive dark on the primaries and back a bit darker than one would expect on pure Glacuous-winged Gull.

Western Gull x Glaucous-winged Gull hybrid, Elwha River Mouth, Clallam County (Washington, USA), 28th October 2011 - copyright Steve Mlodinow

(photo IDs: 1358-1359)

Steve notes that the next one looks as if it might be a American Herring Gull x Glaucous-winged Gull hybrid, but the lack of pale panel on inner primaries suggests that it is Western Gull x Glaucous-winged Gull.  There is too much dark on primaries for pure Glaucous-winged Gull.

Western Gull x Glaucous-winged Gull hybrid, Elwha River Mouth, Clallam County (Washington, USA), 28th October 2011 - copyright Steve Mlodinow

(photo ID: 1357)

For the next one Steve again alludes to the grey on the wing-tips being more extensive and a tad darker than on a pure Glaucous-winged Gull.  It has the head and neck markings of a basic plumaged Glaucous-winged Gull but a mantle color that is more Western-like.

Western Gull x Glaucous-winged Gull hybrid, Elwha River Mouth, Clallam County (Washington, USA), 28th October 2011 - copyright Steve Mlodinow

(photo IDs: 1354-1356)

The next bird is more like Western Gull, but Steve points to the dark eye and heavy markings on the head and chest. Western Gulls should be white headed/chested, or nearly so. Many/most have pale eyes, though this is highly variable.

Western Gull x Glaucous-winged Gull hybrid, Elwha River Mouth, Clallam County (Washington, USA), 28th October 2011 - copyright Steve Mlodinow

(photo ID: 1353)

Steve says the next basic adult bears some resemblance to a Slaty-backed Gull x Glaucous-winged Gull hybrid.  Most of those would show more streaking (vs. smudging) on head and neck than seen on this bird, but on the other hand, there is more streaking here than is typical for Western Gull x Glaucous-winged Gull.  The black on outermost primaries is more extensive than would be seen on Slaty-backed Gull x Glaucous-winged Gull, the white "tongues" should be more extensive - it should extend to P8 - and P9 would most commonly have a white mirror on Slaty-backed Gull x Glaucous-winged Gull.

Western Gull x Glaucous-winged Gull hybrid, Westport (Washington, USA), 20th November 2010 - copyright Steve Mlodinow

(photo IDs: 2188-2191)

On the next bird Steve thinks the light eye might suggest Herring Gull parentage, but the dark mantle and large bill are more consistent with Western x Glaucous-winged.

Western Gull x Glaucous-winged Gull hybrid, Westport (Washington, USA), 18th December 2008 - copyright Steve Mlodinow

(photo ID: 2202)

The primaries are not dark enough for pure Western Gull on the next bird:

Western Gull x Glaucous-winged Gull hybrid, Westport (Washington, USA), 16th September 2010 - copyright Steve Mlodinow

(photo ID: 2201)

The next bird is extremely close to pure Western Gull but has the diffuse smudging on the head as in Glaucous-winged.  Steve tells us that a recent study on birds breeding on Protection Island (near the border of Jefferson/Clallam Counties in the Straits of Juan de Fuca) showed all birds in the colony (thousands) to be hybrids, genetically anyway.

Western Gull x Glaucous-winged Gull hybrid, Clallam County (Washington, USA), 26th October 2012 - copyright Steve Mlodinow

(photo ID: 2305)

Western Gull x Glaucous-winged Gull hybrid, Mukilteo (Washington, USA), January 2011 - copyright Steve Mlodinow

(photo IDs: 1464-1465)

Western Gull x Glaucous-winged Gull hybrid, Mukilteo (Washington, USA), January 2011 - copyright Steve Mlodinow

(photo IDs: 1466-1468)

Western Gull x Glaucous-winged Gull hybrid, Mukilteo (Washington, USA), 30th December 2010 - copyright Steve Mlodinow

(photo ID: 2192)

The remaining photos are mine, taken on a holiday in British Columbia.  I'm not greatly experienced with North American gulls, especially Pacific ones, so my identifications are tentative.  I did get some help soon after I posted the photos online for the first time, so hopefully the IDs are accurate, but I have used the word "probable" to reflect my lower level of confidence compared to the ones identified by Steve.

probable Western Gull x Glaucous-winged Gull hybrid, Clover Point, Vancouver Island (British Columbia, Canada), 9th September 2006 - copyright Dave Appleton

(photo ID: 0530)

probable Western Gull x Glaucous-winged Gull hybrids, Boundary Bay (British Columbia, Canada), 9th September 2006 - copyright Dave Appleton

(photo IDs: 0531-0532)

probable Western Gull x Glaucous-winged Gull hybrids, Esquimalt Lagoon, Vancouver Island (British Columbia, Canada), 9th September 2006 - copyright Dave Appleton

(photo IDs: 0533-0534)

probable Western Gull x Glaucous-winged Gull hybrid, Rathrevor Park, Vancouver Island (British Columbia, Canada), 11th September 2006 - copyright Dave Appleton

(photo ID: 0535)

probable Western Gull x Glaucous-winged Gull hybrid, Oyster Bay Shoreline Park, Vancouver Island (British Columbia, Canada), 12th September 2006 - copyright Dave Appleton

(photo ID: 0536)

Western Gull Larus occidentalis
Glacous-winged Gull Larus glaucescens

American Herring Gull x Glaucous-winged Gull

American Herring Gull x Glaucous-winged Gull hybrid, Mukilteo (Washington, USA), January 2011 - copyright Steve Mlodinow

(photo ID: 1470)

This hybrid seems to occur rather frequently in North America - Steve says it's fairly common during winter on the Washington Coast and in the Puget Trough.  To kick off with here's a bird that Steve's managed to capture well both on the deck and in flight.

American Herring Gull x Glaucous-winged Gull hybrid (same bird as in photo ID 1470 above), Mukilteo (Washington, USA), January 2011 - copyright Steve Mlodinow

(photo ID: 1469)

Next up are two first-cycle birds which look quite similar to Thayer's Gull, as seems often to be the way with this hybrid. Steve points out that these birds are already in first-winter plumage in October, whereas Thayer's would not moult into this plumage until mid-winter. He also notes that they have bills that would be rather hefty for a Thayer's Gull.

American Herring Gull x Glaucous-winged Gull hybrids, Hobuck Beach, Clallam County (Washington, USA), 27th October 2013 - copyright Steve Mlodinow

(photo IDs: 1125-1126)

Next is another that could easily be mistaken for a Thayer's Gull.  Steve notes the short primaries and bit of a secondary "skirt" (secondaries visible below folded wing coverts).  He points out that the secondary skirt is mostly a feature of large west coast gulls such as Glaucous-winged Gull, Western Gull, and Slaty-backed Gull.  He also notes that the greater wing coverts are not evenly speckled, as they should be in a juvenile Thayer's Gull, and that the bird is moulting in first-winter (grey) feathers among its scapulars, something which Thayer's Gulls rarely do before January.  The brownish primaries, secondary skirt and shortish primaries also argue against Herring Gull.  Steve adds that the bird's large-chested and small-headed look are typical of Slaty-backed Gull, but this bird lacked that species' white rump and the first winter grey feathers are not dark enough.

American Herring Gull x Glaucous-winged Gull hybrid, Larimer County Landfill (Colorado, USA), 1st December 2014 - copyright Steve Mlodinow

(photo IDs: 1690-1691)

Here's Steve's commentary on the next bird, taken on the same date and at the same place as the last:

"I was uncertain about this bird's identity and so sought other's opinions.  I feel that the primaries are a bit too dark for "pure" Glaucous-winged Gull (if such a beast exists), but others disagree.  The chesty and big-billed look are wrong for Thayer's Gull.  However, the extensive mottling at the base of the outer tail feathers seems outside the range of Glaucous-winged Gull, and so points back to Glaucous-winged Gull x Herring."

presumed American Herring Gull x Glaucous-winged Gull hybrid, Larimer County Landfill (Colorado, USA), 1st December 2014 - copyright Steve Mlodinow

(photo IDs: 1707-1711)

This bird stuck around and here Steve describes his next encounter:

"It is a frankly peculiar bird.  Perched, it looks more like a Thayer's Gull, due to smallish looking head and bill, though the body seem rather fat for its head, imparting a Slaty-backed Gull like shape (though the plumage is utterly wrong for that species).  In flight, the bird looks bigger, even larger billed. I took stock by asking for opinions from Washington and Alaska, and they agreed with the Glaucous-winged x Herring diagnosis, though certainty must be elusive."

presumed American Herring Gull x Glaucous-winged Gull hybrid, Larimer County Landfill (Colorado, USA), 16th December 2014 - copyright Steve Mlodinow

(photo IDs: 1714-1716)

Here's a thayeri-like adult from the same visit.  Steve says:

"At first glance, this bird recalls a hefty male Thayer's Gull.  However, it was at least as big as the larger Herring Gulls about.  The barred smudging on the chest resembles that of a Glaucous-winged Gull.  The wing extension past tail is on the short side for Thayer's Gull... and the white spotting on the wing would be rather reduced for Thayer's Gull as well."

American Herring Gull x Glaucous-winged Gull hybrid, Larimer County Landfill (Colorado, USA), 16th December 2014 - copyright Steve Mlodinow

(photo IDs: 1714-1716)

Steve's next one a few days later looks a little different:

"Note the huge bill, medium brown wingtips and secondary skirt.  Indeed, this bird (perched view) could be taken for a Glaucous-winged x Western Gull, but the spread wing views show rather pale wings and barring at base of outer tail feathers, a Herring Gull character."

presumed American Herring Gull x Glaucous-winged Gull hybrid, Larimer County Landfill (Colorado, USA), 22nd December 2014 - copyright Steve Mlodinow

(photo IDs: 1719-1722)

And a second bird, same place, same day:

presumed American Herring Gull x Glaucous-winged Gull hybrid, Larimer County Landfill (Colorado, USA), 22nd December 2014 - copyright Steve Mlodinow

(photo IDs: 1717-1718)

And a third, this one an adult (as was a fourth).  Steve tells us that one more like Herring Gull but this one was closer to Glaucous-winged Gull.  The folder primaries are a little too dark and the eye was pale.  Some apparent Glaucous-winged Gulls do have pale eyes but it's a rare feature in that species.

American Herring Gull x Glaucous-winged Gull hybrid, Larimer County Landfill (Colorado, USA), 22nd December 2014 - copyright Steve Mlodinow

(photo IDs: 1723-1725)

Steve separates the next one from Thayer's Gull by its heavy bill and Glaucous-winged Gull like smudging on chest.

American Herring Gull x Glaucous-winged Gull hybrid, Hobuck Beach, Clallam County (Washington, USA), 27th October 2013 - copyright Steve Mlodinow

(photo ID: 1144)

For the next one Steve writes,

"The intermediate primary darkness (between Herring and Glaucous-winged Gull) points to either Thayer's or Glaucous-winged x Herring Gull.  However, the muddy plumage in a first cycle bird (not the crisp speckled plumage of a juv/1st winter Thayer's in January) eliminates Thayer's Gull as does the relatively short primary projection.  Note the odd bill from digging in the mud after rotting fish carcasses.  Yummy!"

For the flight photos he draws attention to the bird's size, the intermediate primary darkness and that a first-cycle Thayer's Gull at this time of year should have less grey on the back as well as more speckling on the greater coverts.

American Herring Gull x Glaucous-winged Gull hybrid, N Teller Lake, Boulder County (Colorado, USA), 20th January 2013 - copyright Steve Mlodinow

(photo IDs: 1221-1223)

American Herring Gull x Glaucous-winged Gull hybrid, Elwha River Mouth, Clallam County (Washington, USA), 28th October 2011 - copyright Steve Mlodinow

(photo IDs: 1365-1366)

For the next bird Steve writes,

"In this photo, the bird has a very Thayer's Gull like aspect.  It is, however, rather short winged and molt is more advanced than that species would normally show in April.  The bird's bill looks delicate for a Glaucous-winged Gull and the primaries a bit on the dark side for that species."

 

American Herring Gull x Glaucous-winged Gull hybrid, Drake Lake, Weld County (Colorado, USA), April 2011 - copyright Steve Mlodinow

(photo ID: 1402)

In these flight shots Steve points out that the white underwing (like Glaucous-winged or Thayer's Gull) is apparent but the bird's bulk is far more like Glaucous-winged Gull. There is also too much dark on the upper primaries for pure Glaucous-winged Gull, and the bill looks petite for Glaucous-winged Gull.

American Herring Gull x Glaucous-winged Gull hybrid, Drake Lake, Weld County (Colorado, USA), April 2011 - copyright Steve Mlodinow

(photo IDs: 1403-1406)

On the next bird Steve says the wings are too short for Thayer's Gull and the dark on the primaries is too extensive.

American Herring Gull x Glaucous-winged Gull hybrid, Brumfield (Colorado, USA), 21st February 2010 - copyright Steve Mlodinow

(photo IDs: 2196-2197)

About the next bird Steve says,

"In some ways, this bird superficially resembles a Herring Gull, with its pale eye and blackish wingtips... but the eye is pale, not the usual white/near-white of a Herring Gull, the bird is rather stout, and the wingtips were not quite as black as they seem in these photos."

American Herring Gull x Glaucous-winged Gull hybrid, Long Beach Peninsular, Pacific County (Washington, USA), 23rd October 2015 - copyright Steve Mlodinow

(photo IDs: 2299-2300)

American Herring Gull x Glaucous-winged Gull hybrid, Everett (Washington, USA), 12th April 2009 - copyright Steve Mlodinow

(photo IDs: 2225-2227)

American Herring Gull x Glaucous-winged Gull hybrid, Sequim, Clallam County (Washington, USA), February 2009 - copyright Steve Mlodinow

(photo ID: 1533)

American Herring Gull x Glaucous-winged Gull hybrid, Chehalis, Lewis County (Washington, USA), December 2009 - copyright Steve Mlodinow

(photo ID: 2224)

Lastly a bird I saw on holiday in British Columbia.  I didn't identify it correctly at the time but it has been pointed out to me that it is most likely an American Herring Gull x Glaucous-winged Gull hybrid, albeit with a caveat that other hybrids may not be ruled out.  It strikes me as being much more boldly patterned compared to Steve's birds above - perhaps that's just because it's earlier in the season, but as always, comments are welcome.

probable American Herring Gull x Glaucous-winged Gull hybrid, Esquimalt Lagoon (Vancouver Island, British Columbia), 9th September 2006 - copyright Dave Appleton

(photo ID: 0537)

American Herring Gull Larus (argentatus) smithsonianus
Glaucous-winged Gull Larus glaucescens