Rare Bird Report 25-B-09

Idaho Bird Records Committee
Rarities Report Form

 

Species: Iceland Gull

 

Reporter: Jay Carlisle

Idaho Bird Observatory, Boise State University, 1910 University Ave., Boise, ID 83725; jaycarlisle@boisestate.edu

 

Other Observers: Heidi Ware … (Harry Krueger separately on 3-4)

 

Date Report Prepared: 3-4-09

 

Date Sighting Occurred:  3-3-09; from ~1130am to ~1150am

 

Locality of Observation: Pickle’s Butte landfill, Canyon Co.

 

Habitat: garbage dump

 

Conditions: p cloudy to cloudy (eventually rain & hail), calm to light breeze but gusts as storm cell moved in; I used Swarovski EL 10x42 binoculars and a Fujinon scope with 20-60x zoom

 

Did you take notes?  not at all

 

Did you consult a field guide or other reference work? after the observation

           

What guide(s) or reference(s) did you consult?

Sibley & National Geographic – as well as various websites

 

Description:  An adult Iceland Gull nearly in breeding plumage.

 

Soon after arrival (around 9am), I caught a 2-second glimpse of an adult, apparent 'white-winged' gull in flight that went back down into the 'pile' (active dumping area) below where we could see and 2.5 hours went by without another sighting of this bird.  In a final scan before leaving, I spotted an adult ‘white-winged’ gull perched out in the open on a ridge of earth near some California Gulls. The bird appeared only slightly larger than nearby California Gulls. It remained perch for 20 minutes as the wind picked up and then rain & hail began and during this time Heidi and I took turns at the scope trying to assess size and structure to differentiate between an adult Glaucous and adult Iceland.  Eventually it flew off with a group of other gulls as the storm picked up in intensity.  Heidi was able to watch the bird take off and I was able to watch the bird in flight for ~ 20 seconds before it disappeared behind the hillside.

 

The bird had a relatively small-looking, rounded head and, for its body size, had a relatively petite yellow bill with a red spot near the end.  The head appeared nearly pure white and did not have obvious streaking as expected for a winter-plumaged bird (suggesting the bird has nearly completed molt into alternate plumage).  We observed pinkish (but not bright pink) legs and a relatively rounded chest/belly.  While perched, and from the angle at which we were viewing the bird (see pics), it was hard to see any color other than whitish in the outer primaries.  Seen in flight, the upperwings were uniformly medium-gray with some whitish in the outer primaries and there were narrow areas of medium-gray (slightly darker than mantle but hard to judge due to lighting conditions – storm – when the bird took flight) in the outer few primaries (I was unable to count but would guess that only the outer 3 primaries possessed these darker marks).

 

Behavior:  1st seen in flight over the active dumping area; later seen perched for 20 min before it flew off towards Lake Lowell.

 

How and when did you positively identify the bird, and what clinched the identification for you?  Based on my first glimpse, I knew Iceland or Glaucous adult by the paleness of the outer primaries.  Once we were able to view the bird while perched, the combination of medium-size (comparable to California Gulls), rounded head, smallish bill, yellowish eyes, pinkish legs, heavy chest/belly, and pale primaries all pointed towards Iceland. 

 

How did you eliminate similar species, and what were they?  Possibilities include Thayer’s Gull (darker wingtips even on the palest adults, usually brownish eyes), Glaucous Gull (pure white wingtips, larger size, longer bill, and usually less-rounded head), and Glaucous-winged Gull (larger size, dark eye, more dark gray in wingtips).  I spoke to Cliff Weisse soon after the sighting and he brought up the potential of a pale-winged (& pale-eyed) adult Thayer’s … at first I thought to myself, “why didn’t I consider that?” (b/c I never once even considered a Thayer’s while looking at the bird) but soon realized that the wingtips were at the pale end of the spectrum for Iceland and so the choice all along was between Iceland and Glaucous … and size and other structural features mentioned above separated the bird from Glaucous.

 

Experience with this species (and similar species):  I have observed 10s of Iceland Gulls on the east coast (especially MA & CT), especially including adults and 1st winter birds, as well as individual birds in SD (1st-winter) and WA (2nd-winter).  I have seen adult Glaucous Gulls in Alaska and 1st or 2nd winter birds in a number of states.  I have seen hundreds of Glaucous-winged Gulls (all ages) along the west coast (especially Washington), including a breeding-plumaged adult within an hour of this sighting at the same location (see separate report).  I have also observed large #s of adult Thayer’s (especially in winter in Oregon). 

 

Heidi has less gulling experience but has seen 8 gull species in Idaho in 2009 and she discovered the above-mentioned Glaucous-winged Gull on the same day – which provided good comparison.  We also had many views of a 1st-winter Glaucous Gull (report likely submitted by Cliff Weisse?) during the same day which provided structural and size comparisons.

 

General birding experience: extensive; 15+ years in US and Latin America

 

Were photo(s), video, and/or audio obtained by you? (If yes, please include or attach)    Yes – blurry but hopefully sufficient.