Verification of Unusual Sight Record
For Utah

Rec. # 2011-15

Common name:

Western Gull (1st cycle)

Scientific name: Larus occidentalis
Date: 18 February 2011
Time: 09:00
Length of time observed: 45 seconds
Number: 1
Age: 1st cycle
Location: Farmington Bay WMA, Unit 1
Distance to bird: 30-50 feet
Optical equipment: Swarovski 65mm, 25-45x eyepiece and Swarovski EL 10x42 bins
Weather: High overcast, no rain
Light Conditions: fairly good
Description:        Size of bird: large gull
(Description:)       Basic Shape: bulky, stout wings
(Description:)  Overall Pattern: brown (see below)
(Description:)            Bill Type: stout gull bill (see below)
Field Marks and
Identifying Characteristics:
At approximately 9am, I was standing on the main road through Unit 1 of Farmington Bay WMA. All birds present at that spot were at some distance, so I was using my scope, but my camera was in the car. I noted a brown gull flying parallel to the road, not at all far out, and towards me. It became readily apparent that the bird was a Western Gull, first cycle. It flew by as close as 30-50 feet and kept going, eventually veering out over the water and away from the road. I had the bird in good view (close enough to see field marks well) for 45 or so seconds. I was using a Swarovski 65mm scope with 25-45x eyepiece initially, then switched to Swarovski 10x42 binoculars when the bird approached closely. The lighting was high overcast, allowing the bird s marks to be seen well.

In general, the bird looked like a stocky all brown large gull that flew with leisurely but strong wingbeats. The head was a tad paler than the body, with darker area on face (resembling what I am used to in young WEGUs). The secondary wing coverts were brown, though the greater secondary coverts were slightly darker, except distally. The secondaries formed a darker brown bar contiguous with the primaries, which were entirely dark brown as were the primary coverts. In other words, the wing looked brown with a dark trailing edge (secondaries and inner primaries) that merged into a dark wedge distally (outer/middle primaries and primary coverts), plus a weak bar on greater secondary coverts that was separated from the darker secondaries but a paler brown strip. This confusingly described upperwing pattern is well illustrated in Sibley s guide. The uppertail coverts and rump were barred dark and light. The underwings looked grayish brown, shading darker out onto the underside o!
f the primaries. The tail appeared all dark brown. The bill looked entirely black and heavy without large gonydeal angle. The vent/undertail/undertail coverts were not noted. Leg color not noted.
Song or call & method of delivery:  
Behavior: see above
Habitat: flying along edge of open water
Similar species and how
were they eliminated:
The shape and size of this bird suggested GW or Western Gull. A 1st cycle Herring Gull would have had a pale panel on inner primaries, should have appeared not as thick winged, and 1st cycle Herring Gulls usually lack the weaker bar on secondary coverts. Also, by this time of winter, most 1st cycle Herring Gulls have a prominent pink base to the bill, though not as extensive as that on a California Gull. The rump/uppertail coverts were more strongly patterned than most Herring Gulls, as well. A California Gull would have a stronger bar on secondary coverts, should have looked obviously slimmer, and had an obviously pink-based, black-tipped bill (among other marks). The ID from GW Gull is self-evident. There was no pale coloration on inner primaries (uppersurface) as is typical of GW x WEGU hybrids, the remainder of the primaries were quite dark, beyond the range of GW x WEGU hybrids in my experience, and the tail was darker than these hybrids typ!
ically exhibit. Finally, GW x WEGU hybrids have limited to no darkening of the undersurface of the primaries.

This bird looked typical for a Western Gull in my experience. It showed no signs of GW Gull intergradation. Having lived in western Washington since 1992, I have had much experience with both Western Gulls and GW x Western Gulls [the hybrids actually outnumber both GW and Western Gulls where I live(d) in Washington; I was passing through UT on while moving from WA to CO]. Herring Gulls and California Gulls would have been obviously different in appearance, for reasons noted above, and I saw many of these in WA as well.
Previous experience with
this & similar species:
see above
References consulted: Sibley, NGS guide, Stokes latest guide
Description from: Notes taken at time of sighting
Observer: Steven G Mlodinow
Observer's address: 1522 Venice Lane, Longmont, CO 80503
Observer's e-mail address:
Other observers who independently identified this bird: none present
Date prepared: 25 Feb [2011]
Additional material: