Observers who saw the bird in the following days include, but not limited to, Cliff Weisse, Zeke Watkins, Tom Watkins, and Adam Brubaker.
LOCALITY OF OBSERVATION
It was observed at Island Park Reservoir, in Fremont County, just northwest of the dam. Exact location is at: 44.4212, -111.4020
HABITAT WHERE THE BIRD WAS OBSERVED
The bird was observed on open water in the reservoir.
SIGHTING DURATION, CONDITIONS, and EQUIPMENT USED
I observed the bird for 10 minutes from 200 meters away. The weather was partly cloudy and a chilly enough for a light jacket to be worn. The cloud-filtered sun was to the right of me used a Swarovski spotting scope and a pair of 8x42 Nikon Monarch 3 binoculars to view the bird.
DID YOU TAKE NOTES?
Yes, later the same day
DID YOU CONSULT A FIELD GUIDE OR OTHER REFERENCE WORK?
Yes, later the same day
WHICH GUIDE(S) OR REFERENCE(S): DID YOU CONSULT?
The Sibley Guide to Birds of North America 2nd Edition
DESCRIPTION OF THE BIRD(s)
The bird was a large, black-bodied duck. It was mostly black with some brown and with conspicuous white secondaries, which were visible on the bird when it was sitting on the water. The bill was also had a significant amount of orange, but only orange, with black at the base.
BEHAVIOR OF THE BIRD(s)
When I first observed the bird he was resting with head tucked in. After a few minutes had passed he began to preen, which was followed by active diving. He was on the water mostly alone with several Western Grebes nearby.
HOW AND WHEN DID YOU POSITIVELY IDENTIFY THE BIRD, AND WHAT CLINCHED THE IDENTIFICATION FOR YOU?
I positively identified the bird as a scoter as soon as I saw it, the large, dark body stood out. When I put the scope on the bird I could clearly see the white secondaries. After a minute or so it started to preen and I could see the rest of the bird. The white secondaries are what I observed first, that is what confirmed the identification.
HOW DID YOU ELIMINATE SIMILAR SPECIES? WHAT WERE THEY?
Similar species are the Black Scoter and Surf Scoter, both of which I have seen before. Both birds were easily eliminated based on the white secondaries and the bill shape and pattern.
WHAT IS YOUR EXPERIENCE WITH THIS (AND SIMILAR) SPECIES?
My experience with this species is limited but thorough. I have observed 3 individuals, including the male observed on June 1, 2017. They varied in age but show that I have experience with the diagnostic features across the species.
DESCRIBE YOUR GENERAL BIRDING EXPERIENCE
My general birding experience is very extensive. I have been well into birding for more than 10 years, especially in the Interior West.
ADDITIONAL INFORMATION (If any)
I believe this bird is a first year because it did not have the white comma at the eye and the bill was noticeably smudgy, giving the impression that it was just getting some orange in this spring. Whereas an adult male would have the white comma and it would have distinct boundaries between the orange and black colorations on the bill.
WERE PHOTO(S), VIDEO, AND/OR AUDIO OBTAINED FROM THIS SIGHTING?
FIRST ROUND VOTING:
Descriptions and photos confirm the identification of White-winged Scoter.
photo and description confirm the identification
Key field marks described & diagnostic photos
I don't think we can eliminate a Stejneger's Scoter from this documentation, but I'm not sure if we need to. I'm not sure if we yet know how regular this newly-elevated taxon will prove to be in the Americas, but there is a record from California and apparently one from Montana. It's probably remote enough that we shouldn't have to explicitly rule it out Otherwise, well documented.
The description and photos were convincing to me.
description and photograph are good.
Description limited, but adequate. Photos diagnostic.