Rare Bird Report 46-B-08

IDAHO BIRD RECORDS COMMITTEE
RARE BIRD REPORT FORM


SPECIES:  


Lesser Black-backed Gull


HOW MANY:


One


REPORTER:  


Bob Davis
173 Stone Run Ln
Idaho Falls, ID 83404


REPORTER EMAIL:  


rhdavis@srv.net


OTHER OBSERVERS:


None


DATE REPORT PREPARED:  


12/17/08


DATE SIGHTING OCCURRED:  


12/12/08


LOCALITY OF OBSERVATION:


Hagerman State Fish Hatchery, Riley Pond, Near Hagerman, Idaho


HABITAT:


Pond


CONDITIONS:


Observed bird for about 30 minutes.  Weather was cold, slightly overcast, calm.  Distance to bird ranged between 20 and 80 yards.  Time was about 3 pm.  Sun glare was not a factor.  Bins were Nikon Monarch 8x42.  Scope was Zeiss Diascope 85 w/ 20-60 zoom eyepiece.  Camera was a Sony Cybershot N1 digital pint and shoot.


DID YOU TAKE NOTES?:  


Yes, during the observation


DID YOU CONSULT FIELD GUIDE OR OTHER REFERENCES?:  


Yes, during the observation


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


NGS 3rd edition, Sibley Guide to Birds 1st Edition.


DESCRIPTION:  


Medium sized white gull, same size as nearby California gulls.  Dark gray mantle; noticeably darker than nearby Ring-billed, California, or Herring gulls, all of which were seen in close proximity to the LBBG.  Wings were black, again noticeably darker than the mantle.  Wings had small mirror observable when bird raised its wings; heavy brown streaking on head and neck and around the eye, yellow iris with dark pupil, large red spot on tip of lower bill, bill dull yellow, legs flesh colored. Head on the bird looked bulkier than the similar size Ca. Gull.  The photos also show the bird sitting higher out of the water than the Ca. Gulls, which goes along with its overall bulkier appearance.


BEHAVIOR:  


Standing, preening, swimming, flying, raising wings while on the water.  Did not observe any feeding.  It swam and stood near gulls of other species making for very good comparison of size and color.  


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


I was pretty sure it was LBBG as I examined the field guides at the scene.  I also took numerous photos and some video of the bird, and looked them over closely at home, comparing size, plumage, and bill markings with other gulls.   


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


Great black backed gull is very much larger.  Ca. gull is much lighter mantled and has black and red spots on the bill, with less extensive head streaking and a dark iris.  Herring and the Thayer's gull complex all have much lighter gray mantles.  Western and Yellow footed gulls are much larger and lack the head streaking.  Slaty-backed gull is much larger and has pink legs with more extensive white on mirror and trailing edge of wings.


EXPERIENCE WITH THIS SPECIES (AND SIMILAR SPECIES):  


 This was a lifer for me, but I've seen thousands of California and Ring billed gulls in Idaho.  


GENERAL BIRDING EXPERIENCE:  


 I consider myself an advanced-intermediate birder.  I've been birding seriously for 12 years and have taken birding trips to Texas, California, Arizona and Costa Rica.


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


 Photo Video