IBRC #11-B-12 /b

IDAHO BIRD RECORDS COMMITTEE
RARE BIRD REPORT FORM

SPECIES: Lesser Black-backed Gull (Larus fuscus) [intermedius ?]
HOW MANY: 2 Adults

REPORTER: Doug Ward 8362 Selkirk Ct. Hayden, ID 83835
REPORTER EMAIL: dougward@frontier.com
OTHER OBSERVERS: Lisa Hardy (photo attached), Jon Isacoff, Tom Munson, and likely many others as the birds were fairly regularly found during three (3) weeks they were around.

DATE REPORT PREPARED: 1 February 2012
DATE SIGHTING OCCURRED: 20 December 2011 – 10 January 2012

LOCALITY OF OBSERVATION: Wolf Lodge and Blue Creek Bays, Lake Coeur d’Alene; Coeur d’Alene, Kootenai County, Idaho
HABITAT: Open water lake, mud flats, and ice.
CONDITIONS: Both adults were first seen together on December 20th, 2011. Observeed around 12pm for 30 minutes at about 100m with 8X40 binoculars and a 15-40X spotting scope. Light was bright overcast. Seen both standing on the ice and flying around with other gulls.

DID YOU TAKE NOTES?: Yes, later the same day
DID YOU CONSULT FIELD GUIDE OR OTHER REFERENCES?: Yes, later the same day
WHAT GUIDE(S) OR REFERENCE(S) DID YOU CONSULT?:
1) “The Sibley Guide to Birds”; Sibley; 2000 :
2) "Gulls: A Guide to Identification"; P.J. Grant; 1982

DESCRIPTION: Medium sized “white-headed” gulls in adult basic (winter) plumage. Two (2) birds present; seen both together and separately on several occasions during the period. Differences in head streaking and bill markings allowed for individual recognition. Descriptions below pertain to both birds with individual notes where applicable.

Plumage: Underparts entirely white. Rump, upper tail coverts and tail white. Head and upper chest white with fine streaking of brownish-grey on the nape and onto the crown; “Adult #1” showed a little more around the eye which looked like a mask at a distance. Mantle, scapulars, coverts, and tertials evenly colored dark slate grey; noticeably darker than adult California Gulls (L. californicus) present. Upper wing: Outer primaries were black, though not noticeably demarcated from the rest of the back leading to the possibility these were from the “Intermedius” group. There was a single white mirror on P10. Inner primaries and secondaries appeared to be the same shade as the coverts. All flight feathers showed a thin white trailing edge. Under wing: Pale grey with noticeably dark flight feathers forming a broad trailing edge.

Bill / Feet / Eye Color: Bills were bright yellow with a large bright red gonydeal spot; “Adult #2” showed a dusky area near the tip as well. Their irises were pale yellow. Legs and feet looked either grayish-yellow or flesh-yellow depending on the day or lighting conditions; never looked bright yellow.

Structure: Light weight, medium sized gulls – similar size to California Gulls present. Appeared “skinny” in comparison to Herring (L. argentatus) and California Gulls; accentuated by the long wing projection of these birds. Bills nicely proportioned with a very weak gonydeal angle.
BEHAVIOR: Seen resting on ice or bare ground, flying around feeding, and swimming in open water.

HOW AND WHEN DID YOU POSITIVELY IDENTIFY THE BIRD, AND WHAT CLINCHED THE IDENTIFICATION FOR YOU? Lisa Hardy had reported seeing a possible adult Lesser Black-backed Gull (L. fuscus) earlier in the day so I had the possibilty on my mind. When the first bird flew in it was pretty obvious as it had a very dark back (little contrast between the black primaries and the rest of the back), bright yellow bill with a lot of red on the gonydeal spot, and pale eyes. Also it's very light weight "jizz" and long wings fit the identification.
HOW DID YOU ELIMINATE SIMILAR SPECIES, AND WHAT WERE THEY? While fairly straight forward identification, other dark backed gulls should be discussed. Many California Gulls (L. californicus) were in direct association with both birds. All had paler mantels than these two, and were heavier in appearance. Also, the pale yellow irises eliminate this species. Black-tailed Gull (L. crassirostris) crossed my mind briefly when “Adult #1” first flew in as it had a lot of red on its bill, very dark back, and eye crescents within the streaking around its eye. A quick check of the all white tail shot this idea down. Great Black-backed Gull (L. marinus), Western Gull (L. occidentalis), “Vega” Herring Gull (Larus argentatus vegae), and Slate-backed Gull (L. schistisagus) were also considered but generally ruled out based on these birds light weight structure and long wing projections. In addition, these birds showed yellow leg coloring further eliminating this group.

EXPERIENCE WITH THIS SPECIES (AND SIMILAR SPECIES): I've seen a couple of dozen Lesser Black-backed Gulls (L.f. graellsii, intermedius, & fuscus) previously in the U.K., New Jersey, Colorado, and Kenya. These were my first for Idaho.
GENERAL BIRDING EXPERIENCE: I've been birding for 38 years and consider myself advanced.

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

This photo was taken at Wolf Lodge on 24 December 2011 by Lisa Hardy.