While birding DeKorte Park in the Hackensack Meadowlands, we noticed an unusual
looking gull feeding with a small group of crows on what appeared to be a roll
or bagel. A 1st winter Herring Gull landed nearby and briefly and
unsuccessfully contested this bird for the food. We were able to observe the
bird carefully at distances ranging from 30 to 100 feet for approximately a half hour
from various angles. During this time, the bird engaged in several short
flights, affording good views of the upper and under wings.
Description (From field notes taken at the site):
Herring Gull size (from direct comparison; i.e. NOT a runt)
White head with a dark eye and dark line through eye, light streaking on nape.
All black bill, not as heavy as HEGU, did not flare out.
Underparts basically white, dark gray mantle, darker than HEGU, lighter than
LBBG. Feathers on mantle and scapulars slightly mottled, a few (just up from
scapulars) with black sub-terminal marks.
Median Coverts pale brown, greater coverts darker brown. All feathers fringed
in white and mottled to some degree.
Tertials chocolate brown, narrowly fringed white, uniform color with no internal
markings.
Primaries slightly darker brown with very narrow lighter edges.
Long winged - extended well beyond tail.
Gray streaking on flanks.
Tailband same color as primaries, even in width, narrowly fringed in white.
Outer web of outer tail feather pale, barred.
Legs pale flesh, medium size.
In flight:
Tail, rump and back: sub-terminal tail band same color as primaries. Base of
tail white, although the outermost feather showed a few dark bars above the tail band. Rump and upper coverts white, barred with dark - less barring than any
smithsonianus Herring Gull.
Upper wing pale with dark secondary bar. Outer primaries dark with light window
in the inner primaries.
Undertail coverts, base of tail, up to vent finely banded or mottled.
Underwing linings unmarked medium brown contrasting with paler gray, relatively
unmarked flight feathers. Lighter window visible in inner primaries.
Due to the gray of the back and scapulars, we initially thought the bird was in
2nd winter plumage. After reviewing our photographs and the June, 1995 Limicola
article, we feel the bird is actually in 1st winter plumage. Photographs and
paintings accompanying the article, as well as one of the observer's (Lewis)
photos of L. cachinanns in Portugal, show the gray back and scapulars
contrasting with the brown coverts in 1st winter plumage. The photos also show
the black terminal bars and feather shafts on the upper scapular and mantle
feathers. This age is further confirmed by the worn condition of the tertials.
Similar Species:
HEGU and LBBG both ruled out by the whiteness of the body and head as well as
the contrasting pattern of back and wing and structural differences as shown in
the enclosed photos.
HEGU is further ruled out by the brown underwing linings contrasting with paler
gray flight feathers, wing length and tertial pattern.
LBBG is further ruled out by the upperwing pattern with a conspicuous dark
secondary bar contrasting with paler wing linings and the conspicuous pale
"window" in the inner primaries.
GBBG is ruled out by size, wing length, bill and head structure. Additionally,
GBBG would show more uniform black and white "checkering" over the entire back
and wing rather than the contrast between gray back and brown wings of this
bird.
Other potential vagrants can be ruled out similarly on a combination of the
marks noted above.
Since then, photos of the bird were examined by a number of European experts. There was no unanimity. All agreed that the bird is first winter. Most did not think that the bird was a michahellis . The bird may well be a Yellow-legged Gull from an Atlantic island (atlantis); a hybrid form; heuglini ; or even a new taxon (!).
To me, that seems to be about the right order of probabilities.
We are especially interested in hearing from people who can speak to the possibility of heuglini. At least from Shirihai's book The Birds of Israel, that seems like a real possibility.
Click on the thumbnail image to load the full image. Set your monitor to at least thousands of colors.
In this and the other slides, note the very long pointed primaries, the worn tertials and greater coverts, the greater covert bar darkening distally, the pale lesser coverts, and the scapulars with dark diamond shapes. Note also the all dark bill and the white head, with dark gray coming up onto the nape.
This and the next are slightly greenish. Exaggerated upright posture due to our close proximity.
Can anyone positively identify the crows, especially the one in front?
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