Verification of Unusual
Rec. # 2008-31
|Scientific name:||Larus glaucoides|
|Date:||5 November 2008|
|Length of time observed:||1 hour|
|Elevation:||about 4500 feet|
|Distance to bird:||estimated 10-30 yards|
|Optical equipment:||Nikon Monarch 10x42 binoculars, Nikon 20x Sky and Earth spotting scope, Nikon D80 digital SLR with Nikon 80-200 f/2.8 lens, Pentax Optio W30 digital camera|
|Weather:||Cloudy and cold, approximately freezing. A storm recently passed through, but it was not precipitating during the observation.|
|Description: Size of bird:||Approximately the same size as the California Gulls it was with. Distinctly and obviously smaller than nearby Herring Gulls.|
|(Description:) Basic Shape:||Long body, rounded head. See details below.|
|(Description:) Overall Pattern:||Pale mottling of gray-brown on a white background. Much paler than other immature gulls (California, Ring-billed, and Herring) nearby. See details below.|
|(Description:) Bill Type:||Very petite bill. Expression, including bill length, was reminiscent of a Mew Gull. Bill was pink at base and graded into black at the tip.|
Field Marks and
This was a smallish pale-winged immature gull. The head was small and round,
with a petite bill suggesting Mew Gull in shape and proportions. The eye was
dark. The bill was pink at the base but graded into black at the tip. The
transition from pink bill base to black tip was a visible gradation, not an
abrupt change as in a Glaucous Gull. The poor resolution of some of my photos
gives the impression of an abrupt change, but in the field and in other photos
the black ran up the bottom edge of the top mandible at least half way to the
gape. The gonydeal angle was weak.
The nape and breast of the bird seemed to be a fairly uniform milky brown with some smudginess. The wing coverts were crisply patterned in pale brown on a light milky background. The folded primaries in particular were very pale, as in Glaucous Gull, but extended well beyond the tip of the tail. They were the same tone of gray-brown as the wings. The tertials were finely patterned, not dark-centered (as they would be for Thayer's Gull).
In flight, the wings and tail appeared very pale and nearly patternless. The primaries did not contrast with the rest of the wing, and did not contrast within themselves as they would in a Thayer's Gull. The tail was pale brown and did not have a dark tail band. The secondaries also did not appear darker than the rest of the wing.
The legs were pale pink, approximately matching the color and tone of the base of the bill.
The overall body size was slightly larger than most of the nearby California Gulls, but much smaller than the Herring Gulls, However, proportionally this bird seemed to have a smaller, rounder head and smaller bill than the California Gulls, despite its larger size
|Song or call & method of delivery:||None certain to have come from this individual.|
|Behavior:||Generally loafing with a large mixed flock of several hundred other gulls, occassionally picking at food in the water. Seemed to usually, but not always, be towards the edge of the flock. Several times I observed a Herring Gull charge at this gull, which would cause it to spread its wings and fly/hop a short distance away.|
|Habitat:||Shallow muddy pond designed for shorebird habitat. Surrounding area is largely agricultural, with the Logan Landfill very near to the east.|
were they eliminated:
(Field marks in this section refer to immatures of each species, typically
first-winter immatures unless otherwise mentioned.)
Glaucous-winged Gull: Glaucous-winged Gulls are considerably larger than this gull, with larger bills and larger, blockier heads. This gull had a small, rounded head with a petite bill, and was about the size of a California Gull, which is much smaller than a Glaucous-winged Gull. This bird had a pale base of the bill, whereas Glaucous-winged Gulls typically have all-dark bills. This gull was patterned in the wing coverts, whereas Glaucous-winged Gulls have realatively smudgy unpatterned wing coverts. Glaucous-winged Gulls typically have short primary projection, whereas this bird had relatively long primary projection.
Mew Gull: This gull had the proportions of a Mew Gull but had pale
wingtips, which are not shown by Mew Gulls. Also, it was considerably larger
than a Mew Gull, as mentioned by its comparison with California Gulls.
Glaucous Gull: Most Glaucous Gull subspecies can be easily discerned from
this bird by their large size, robust bill, and large head with a sloping
forehead. However, the subspecies "barrovianus", which is found in Alaska, can
overlap with Iceland Gulls in size. Plumage is also nearly identical between
Iceland Gulls and Glaucous Gulls, so we must pay close attention to structure.
One diagnostic trait is wing length: Glaucous Gulls have wing tips that barely
project beyond the tail, whereas Iceland Gulls have long wing tips that project
well beyond the tail, as shown by this individual. Even in a small female "barrovianus",
the head is relatively large and flat compared to Iceland Gulls and this Gull. "Barrovianus"
do not have the huge robust bill typical of Glaucous Gulls, but their bills are
still larger and have a stronger gonydeal angle than shown by this bird, which
has a bill typical of a smallish Iceland Gull. Although this bird has a pink
bill base and a dark tip, this demarcation is not as distinct as the
"ink-dipped" tip of a Glaucous Gull, although extreme Kumlein's gulls can
approach this ink-dipped look even in their first winter.
this & similar species:
|I have seen Iceland Gulls on one occassion in New Hampshire. I have seen Thayer's Gulls dozens of times in Washington, where I used to live, and a few times in Utah. I have seen Glaucous-winged Gulls thousands of times in Washington. I have seen Glaucous Gulls twice, once in Utah and once in Idaho.|
|References consulted:||None at the time of observation. Identification was confirmed using the Sibley Guide to Birds, National Geographic's Field Guide to the Birds of Western North America, Howell and Dunn's Gulls of the Americas, and Kaufman's Advanced Birding.|
|Description from:||Notes made later|
|Observer:||Ryan P. O'Donnell|
|Observer's address:||1098 Crescent Drive, Logan, Utah|
|Observer's e-mail address:||Ryan@biology.usu.edu|
|Other observers who independently identified this bird:||Jason Pietrzak found the bird on 4 Nov 2008 but didn't know what it was. He sent photos to me and then Craig Fosdick and I identified the bird in the field today, 5 Nov. Jason later relocated the bird and identified it in the field.|
|Date prepared:||5 Nov 2008|
|Additional Comments:||I will be submitting several photos that I took. Jason Pietrzak has taken several better photos and will be submitting those soon with his report.|