first cycle Glaucous-winged x Herring Gull

first cycle
Glaucous-winged x Herring Gull

Fig 1) This bird, still with juvenile scapulars, superficially resembles a Thayer's Gull. However, the lesser and median coverts are rather messy, not neatly checkered, and the greater coverts are extraordinarily plain, which is find for Glaucous-winged but very wrong for Thayer's Gull. The bill is rather thick, and note the small-eyed look-- Thayer's typically imparts a big-eye-on-a-dainty-head look. December 27, 2011. Redding, California. Photo courtesy of Bob Yutsy.

Fig 2) Same bird as Fig 1. The bird looks bulkier in this image and much closer to Glaucous-winged in structure. Note the solid tail; Thayer's would always show some barring on the outer rectrices at least. December 27, 2011. Redding, California. Photo courtesy of Ray Bruun.

Fig 3) Another psuedo-Thayer's Gull, but too large and too muddy and too far advanced in molt. This one, presumably a male, has the large bill of a Glaucous-winged Gull, but with some pink in it from the Herring side. December 10, 2011. Davis, California. Photo courtesy of Steve Hampton.

Fig 4) Best described as a large blurry Thayer's Gull, note the rounded head, the bill shape and color, the folded primaries, and the messy patterning on the upperparts (including the greater coverts and tertial tips). February 24, 1998. Santa Clara County, California. Photos courtesy of Mike Rogers.

Figs 5 and 6) Same bird as Fig 4. Note the Thayer's like pattern on the flight feathers, with dark outer webs and pale inner webs all the way out to P10. Slaty-backed has more solid (and usually darker) P9-10 and more pronounced terminal spots on the inner primaries. In flight, the darkest colors on this bird, on the outer webs of the flight feathers and on the tail, are a fairly washed brown. Slaty-backed is usually a tad darker in these areas than this bird.

Fig 7) The bird in the foreground appears to be a typical late season hybrid. Some adult gray is coming in on the mantle, and the coverts are very faded. The brownish bird just behind is a Thayer's Gull, one of the most similar species to this hybrid. Note the Thayer's finer bill and smaller head. The standing bird is a California Gull, while the others are Herring Gulls. March 11, 2011. Davis, California. Photo courtesy of Steve Hampton.

Fig 8) Another late season bird, although they usually appear fairly muddy thru much of the winter. A Thayer's Gull is to the left. March 16, 2011. Davis, California. Photo courtesy of Steve Hampton.

Fig 9) This bird seems like a regular Glaucous-winged Gull, except that it is so well-patterned on the coverts and tertials. The bill is typical for a Glaucous-winged Gull. It is still in juvenile plumage except for a few first winter feathers coming in on the scapulars. January 20, 2000. Palo Alto Baylands, California. Photo courtesy of Mike Rogers.

Fig 10) Figures 10-12 are the same bird. It looks like a Glaucous-winged Gull with darker primaries. Thayer's is ruled out by the bulky size and advanced worn coverts. March 23, 2011. Clearlake, Calfornia. Photo courtesy of Steve Hampton.

	Fig 11) In flight, the dark/like pattern, although muted, resembles Herring Gull. This pattern rules out Gl-W x Western Gull.
Fig 12)