RECORD #: 31-B-06

IDAHO BIRD RECORDS COMMITTEE
RARE BIRD REPORT FORM

SPECIES:

Lesser Black-backed Gull

HOW MANY:

1

REPORTER:

Chuck Trost, 225 N. Lincoln, Pocatello, ID 83204, 208-233-4538

REPORTER EMAIL:

trostchuck@cableone.net

OTHER OBSERVERS:

Marty Collar, Dave and Elise Faike

DATE REPORT PREPARED:

7-27-06

DATE SIGHTING OCCURRED:

May 11, 2003

LOCALITY OF OBSERVATION:

Mouth of Crystal Springs onto American Falls Reservoir, about a mile north of where the Snake River enters the reservoir.

HABITAT:

On an island - mudflat

CONDITIONS:

Kowa 80mmED scope 20-60. Warm calm morning, sun still to the east, so viewing conditions good from about 100 yards.

DID YOU TAKE NOTES?:

Yes, later the same day

DID YOU CONSULT FIELD GUIDE OR OTHER REFERENCES?:

Yes, during the observation

WHAT GUIDE(S) OR REFERENCE(S) DID YOU CONSULT?:

Natl. Geographic, large Sibley

DESCRIPTION:

A fairly large gull with a dark back, yellow bill with a dark tip, yellow legs and feet, and a few white spots visible on the primary tips. The end of the tail was dark, but it otherwise looked like an adult (I presume it was a 3rd year bird).

BEHAVIOR:

Resting on the island with 3 Calif. Gulls, 2 Ring-billed Gulls, 6 juvenile Herring Gulls, 4 Bonaparte's Gulls, 6 Forster's Terns, and 5 Caspian Terns. No interactions noted in an hour of watching it.

HOW AND WHEN DID YOU POSITIVELY IDENTIFY THE BIRD, AND WHAT CLINCHED THE IDENTIFICATION FOR YOU?

I called it out immediately to Marty, then after consulting the field guides we both agreed.

HOW DID YOU ELIMINATE SIMILAR SPECIES, AND WHAT WERE THEY?

The size was correct - slightly smaller than the Herring Gulls and larger than the California Gulls. The dark back and yellow legs were diagnostic.

EXPERIENCE WITH THIS SPECIES (AND SIMILAR SPECIES):

I have seen this species in Europe, and at a Boise landfill.

GENERAL BIRDING EXPERIENCE:

I have been birding for about 60 years, and consider myself to have expertise.

WERE PHOTO(S), VIDEO, AND/OR AUDIO OBTAINED BY YOU?:

None

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31-B-06 - ADDENDUM to C. Trost's report added at the request of S. Sturts.

I also saw this individual on May 11, 2003. Chuck was not there but Marty, Dave, Elise and Darren Clark were all present. To Chuck's description I can add that the iris was yellow, there were no white windows in the primaries, and the mantle was very dark, contrasting little with the primaries. I don't know the extent of variation of mantle shade in graellsii Lesser Black-backed Gull but this individual struck me as being dark enough to be of the intermedius subspecies, appearing almost black in the field. I've seen a few LBBGs in NJ, UT and ID and this was easily the darkest individual I've seen.

Cliff Weisse
7/27/2006