Sighting Record for Utah

Common name:	Glaucous-winged Gull
Scientific name:	Larus glaucescens
Date:	18 Nov 2000
Time:	9:00 - 9:30 am
Length of time observed:	30 minutes
Number:	1
Age:	juvenile/1st winter
Sex:	?
Location:	Antelope Island Causeway
County:	Davis
Latilong:
Elevation:
Distance to bird:	30 meters
Optical equipment:
Weather:	clear and sunny
Light Conditions:	bright
Detailed description of bird:	A large gull (larger than nearby calif gulls) with a large head and flat sloping forehead. Large all black bill with a distinctive sharp gonydeal angle on the lower bill. Uniform pale brown body plumage including the tail and primaries which were the same uniform pale brown color as the mantle and the rest of the body plumage. A uniform pattern of pale markings on fringes ran across the lesser median wing coverts. Pale fringe on the tips of the primaries. Pink legs, dark eye.
Song or call & method of delivery:	None.
Behavior:	feeding on brine flies at the waters edge of the Great Salt Lake
Habitat:	Sandy beach at waters edge of Antelope Island Causeway
Similar species and how were they eliminated:	Glaucous Gull: 1st winter. 2 toned bill - pale base with black tip. Overall body plumage paler (almost white) with coarser & more irregular pattern of markings on scapulars & wing coverts. paler primaries contrast with the upper body plumage. Thayers gull: 1st winter: Smaller bill, smaller more rounded head. Primaries darker than upper body plumage. dark band on tail. Herring gull: 1st winter: Dark brown primaries and secondaries which contrast with rest of body plumage, Dark tail, Dark barred rump. Glaucous-winged - Western hybird: This is a possibility. A 50/50 hybrid would probably show somewhat darker wingtips than the rest of the body plumage, less flat head, less pronounced bill shape a generally more integration of characteristics of the 2 hybridized species. As mentioned in my narration on the other apparent glaucous-winged gull, hybridization is common among Glaucous-winged and other gulls including Western, Herring, and Glaucous. The gull described fits the overall description of a 1st winter glaucous-winged gull but may in fact contain genes of one of the other species from hybridization and backcross from the distant past.
Previous experience with this & similar species:	I have seen several apparent Glaucous-winged gulls on the pacific coast and a few in Utah the past several years.
References consulted:	P.J. Grant: Gulls a guide to Identification. Second edition. The Sibley Guide to Birds.
Description from:	Notes at time of sighting.
Observer:	Terry Sadler
Observer's address:	887 Germania Ave. Murray, UT 84123
Observer's e-mail address:	sadler@xmission.com
Other observers who independently identified this bird:
Date prepared:	27 Dec 2000
Additional material:	3 Photos (large file -- will take a while to download) , Original Document