Herring Gull vs. Thayer's Gull
Text by Greg Gillson
Photographs by Phil Pickering.
Copyright © 2000, all rights reserved.

Herring and Thayer's gulls are superficially quite similar. There are plumage and structural differences, however, that help separate them at all ages. [All photos taken at D River, Lincoln county, Oregon.]

Herring Gull, adult winter   Thayer's Gull, adult winter
Herring Gull, adult winter
larger view

January 2000

These two photos, Herring on the left and Thayer's on the right, show typical winter adults. First, notice the pale gray mantle--paler than California, Mew, and Glaucous-winged, and about the same shade as Ring-billed Gull. The wing tips of Herring are jet black, with white mirrors and apical spots.

Adult Herring Gulls have pale eyes, rather flat foreheads, and fairly long, stout, bills of rather uniform thickness throughout. Thayer's Gulls, on the other hand, have darker eyes, round crowns, and dainty bills which often show a yellow-green tinge. The red gonys spot is often diffuse on Thayer's gull and pronounced on Herring Gulls.

Some, but not all, Thayer's Gulls appear slightly darker mantled than Herring Gulls in a side-by-side comparison. Notice also that the legs of adult Thayer's Gulls usually appear brighter pink than most other gulls. The wing tips of Thayer's Gulls in our area are usually, but not always jet black. More eastern birds, and sometimes Thayer's in the Pacific NW, show very dark gray wing tips. Again, these are not diagnostic, but can be good clues.


Thayer's Gull, adult winter
larger view

January 2000
Herring Gull adult wing tip   Thayer's Gull, adult wing tip
Herring Gull, adult winter wing tip
larger view

February 2000

The folded wing pattern similarity between adult Herring and Thayer's when the birds are on the ground disappears once the birds take flight. The end of the wing of Herring Gull (left) is a black triangle of 5-7 primary feathers with two white interior spots (mirrors). This large black triangle is repeated on the underwing.

The open upper wing of Thayer's Gull (right) has much reduced black, compared to Herring. The narrow tongues of black are on the leading edge of the primary feather and hidden from below. Thus, there are only some small black bands visible on the open underside of the outer primaries of a Thayer's Gull wing. The underside of a Thayer's Gull wing is esentially all-white, with only 3 or 4 small black tips.


Thayer's Gull, adult wing tip
larger view

December 1999
Herring Gull, adult wing tip   Thayer's Gull, adult wing tip
Herring Gull, adult wing tip
larger view

November 1999

The folded wing pattern of adult Herring (left) is repeated on the underwing. In the photo you can see the underside of the far primary is black with a white mirror, similar to the upper surface.

The folded wing of Thayer's Gull (right) shows the underside of the wing is nearly white, in contrast to the upper surface.


Thayer's Gull, adult wing tip
larger view

January 2000
Herring Gull, first-winter   Thayer's Gull, first-winter
Herring Gull, first-winter
larger view

November 1999

The head and bill shape are critical in all plumages. Here, in first-winter plumage you can note the flat head and large bill of the Herring Gull on the left. On the right, Thayer's Gull is round-crowned and has a smaller bill.

At first glance the plumage of these birds may appear identical. However, note that the Herring Gull has darker wing tips, almost blackish, while the Thayer's wing tips are a dark coffee brown. Notice also the general coloring of the Herring Gull is made of dark brown feather centers and whitish edges and bars. The coloring of the Thayer's Gull is more uniform brownish with cream edges and bars, creating a distinctive checkered pattern to the coverts. The wing tips are darker than the tertials and rest of the wing, the bill is small, eliminating consideration of a first-winter Glaucous-winged Gull.

By about March the bills of Herring Gulls become pale at the base. Thayer's Gulls retain mostly-dark bills until second-winter. The photo of the Thayer's on the right shows the obvious white crescents on the tips of the primaries, a feature generally lacking in Herring Gulls. Other marks include longer primary extension past tail, and shorter legs.


Thayer's Gull, first-winter
larger view

February 2000
    Thayer's Gull, first-winter

 

First-winter Thayer's Gulls (right) are a bit different from Herring Gulls in flight as well. As the photo to the right shows, the contrasting light and dark primaries and secondaries of Thayer's have solid dark tips. The flight feathers on Herring Gull are more uniform dark brown, without the contrasting pale centers and dark tips. The inner primaries, however, have pale bases, creating a whitish "window."


Thayer's Gull, first-winter
larger view

November 1999
Herring Gull, second-winter    
Herring Gull, second-winter
larger view

March 2000

The Herring Gull shows pale bases to the inner primaries, called "windows." In overall coloration the tailband and flight feathers are blackish, while those of Thayer's are pale brownish, more similar to Glaucous-winged Gulls.

The tail is mostly blackish with a white rump, while the Thayer's Gull has a brown band at the end of the mostly white tail.


Herring Gull, second-winter   Thayer's, second-winter
Herring Gull, second-winter
larger view

November 1999

By the second winter the eye of Herring Gull (left) has turned pale. In general, Thayer's Gull (right) is paler and less heavily marked on the body, and the wing coverts show less contrast than Herring (by late winter, the brownish plumage of all gulls fades quite a bit). Of course, head and bill shape are still key in identifying birds at this (and every) age. Notice also the darker pink legs of Thayer's and the brownish primaries and white crescents on the dark tips.


Thayer's Gull, second-winter
larger view

March 2001
Herring Gull, Third-winter   Thayer's Gull, Third-winter
Herring Gull, third-winter
larger view

February 2000

Third-winter gulls look quite similar to adults with the following exceptions. The bill usually is not yellow with a red gonys spot. Rather, it is pinkish with black tip. The body plumage is more mottled on the head and breast. The tail is mostly white with a remnant of a smudged tail band. The wings lack the large white mirrors and apical spots or, if present, they are much smaller than in adult winter plumage.

The Herring Gull (left) shows the typical pale eye and flat head profile. The Thayer's (right) shows rounded head, dark eye, and bright pink legs. It has a larger bill than some other Thayer's, probably indicating a male. The secondary coverts have not fully molted in, as can be seen by some older brownish covert feathers.


Thayer's Gull, third-winter
larger view

February 2000
    Thayer's Gull, Third-winter

 

The Thayer's here (right) is the same bird as the above photo. The full tail band is typical for Thayer's Gull, while the Herring Gull (above, left) has only a few dark ends. The adult-like primary pattern is apparent.


Thayer's Gull, third-winter
larger view

February 2000
Herring Gull, adult winter   Thayer's Gull, adult winter
Herring Gull, adult winter
larger view

February 2000

Finally, in the photo to the right, the left bird is a Thayer's Gull with a rather pale eye. The (somewhat) smaller bill (males have larger bills than females), round crown, brighter pink feet, and (most importantly) the reduced black in the pattern of the folded wing identify the bird as Thayer's and not Herring. Notice how dark the Western Gull appears in the background. Many newer gull watchers, and visitors from outside the Pacific NW, misidentify our paler Western Gulls as Herring and Thayer's Gulls.

Observe on the Western Gull the massive bill, with a swollen gonys spot. Also note the straw-colored bill of the Thayer's (and Herring) as opposed to the more orangish ("school bus yellow") color of the Western Gull.

Light conditions can make mantle color appear lighter or darker. Of course, photographs can be especially misleading. The Herring in the left photo is actually the same shade as the Thayer's in the right photo, despite their appearance in these photgraphs.

Thayer's Gull, adult winter
larger view

November 1999


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