Verification of Unusual
Rec. # 4-2001
|Scientific name:||Larus glaucescens|
|Date:||18 Nov 2000|
|Time:||9:00 - 9:30 am|
|Length of time observed:||30 minutes|
|Location:||Antelope Island Causeway|
|Distance to bird:||30 meters|
|Weather:||clear and sunny|
|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|
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.|
P.J. Grant: Gulls a guide to Identification. Second edition.
The Sibley Guide to Birds.
|Description from:||Notes at time of sighting.|
|Observer's address:||887 Germania Ave. Murray, UT 84123|
|Observer's e-mail address:||firstname.lastname@example.org|
observers who independently identified
|Date prepared:||27 Dec 2000|
|Additional material:||3 Photos (large file -- will take a while to download) , Original Document|
Go to Main List of Sighting Under Review