Verification of Unusual Sight Record
For Utah

Rec. # 2008-09

Common name:

Yellow-billed Loon

Scientific name: Gavia adamsii
Date: 20 May 2008
Time: 6:00PM
Length of time observed: 20 minutes
Number: 1
Age: Adult
Sex: Unknown
Location: Jordanelle Reservoir
County: Wasatch
Elevation: 6200 ft
Distance to bird: 50-200m
Optical equipment: Nikon Monarch 10x42 ATB binoculars, Nikon D80 camera with 18-135 zoom lens
Weather: Overcast, wind increasing during the observation and rain beginning at the end of the observation, becoming stormy
Light Conditions: Overcast.
Description:        Size of bird: Slightly larger than the Common Loon with which it was associating
(Description:)       Basic Shape: Loon shape, waterbird body form.
(Description:)  Overall Pattern: Black and white.  Black body with a grid of white on the dorsal surface of the folded wings.  Black head with white neck markings.  Yellow bill.
(Description:)            Bill Type: Large loon bill, pure pale yellow, more upturned than the common loon with which it was associating.
Field Marks and
Identifying Characteristics:
This adult breeding-plumage Yellow-billed Loon was associating with an adult breeding-plumage Common Loon during the entire period of observation, making for great side-by-side comparisons.  Both loons had black bodies with checkerboard patterns of small white patches on the dorsal surface of the wings. The Yellow-billed Loon seemed to have somewhat more white on the wings than the Common.  Both birds had black heads with collars of white vertical striping.  No differences between these collars were noticed. The Yellow-billed loon had a slightly larger head than the Common Loon with a steeper forehead, giving it a slightly squarer-looking head than the common.  This was particularly evident when the birds were sleeping.  The most obvious difference between these two birds was the pale yellow bill of the Yellow-billed Loon, in contrast to the solid black bill of the Common Loon.  The Yellow-billed Loon's bill had a straight culmen and a convex lower bill edge, giving a upturned look to the bright bill.
(see photos)
Song or call & method of delivery: None.
Behavior: Loafing on open water.  Neither bird was seen to forage, dive, feed, fly, court, etc.  The birds sometimes had their heads up, but spent most of the time with the heads tucked down, sleeping.  The Yellow-billed Loon yawned several times.
Habitat: Open water of a reservoir.
Similar species and how
were they eliminated:
In breeding plumage, this species is only really similar to a Common Loon.  Because this bird was seen with a Common Loon, see the description of field marks above for a comparison of the features shown by this bird to distinguish it from a Common Loon.  Other loon species are all smaller, and also have dark bills. 
Previous experience with
this & similar species:
This was my first observation of a Yellow-billed Loon.  I had previously seen every other Loon (Gavia) species, with the majority of observations of Common Loons.  I have been actively birding for about nine or ten years. 
References consulted: The Sibley Field Guide to Birds of Western North America and Kaufman's Field Guide to Birds of North America
Description from: From memory
Observer: Ryan P. O'Donnell
Observer's address: 1098 Crescent Drive, Logan UT 84341
Observer's e-mail address: Email:
Other observers who independently identified this bird: This bird was initially photographed by Marci Welch on 18 May 2008, as posted on the Utah Birds webpage.  Her photographs prompted me and many others to chase the bird.  According to posts on Birdtalk and Birdnet, this bird was also seen by Kristin Purdy, Pat Jividen, Alton Thygerson, Dave Hanscom, Deb Thornton, Larene Wyss, Edson Leite, among others who were not named or did not post.
Date prepared: 26 May 2008
Additional material: Photos
Additional Comments: This bird was seen by many people, but has apparently not yet been submitted to the Bird Records Committee, so I thought I'd submit my observations in the hope that it would encourage others to submit theirs.   
There are better photographs available of this bird (especially those by Marci Welch), but I have submitted two that I took.  Both photos show a Common Loon on the left and a Yellow-billed Loon on the right.  The first (YBLO1.jpg) shows both birds with their heads up.  The pale bill of the YBLO is evident in this photo, albeit at a distance.  Although it is difficult to judge relative distance in this photo, I believe you can also see a difference in the size of the two birds.  The second photo shows the two birds sleeping.  The head shape is difficult to judge in the Common Loon in this photo, but the photo shows the relatively square head of the Yellow-billed Loon.