Sighting Record for Utah

Common name:	Red-throated Loon
Scientific name:	Gavia stellata
Date:	10/24/2015
Time:	11:45am
Length of time observed:	~2 hours
Number:	1
Age:	Juv.
Sex:	Unk.
Location:	Rockport Reservoir
County:	Summit
Latilong:
Elevation:
Distance to bird:	~200-300m at closest
Optical equipment:	Nikon Fieldscope III 20-60x40
Weather:	Sunny
Light Conditions:	Moderate. Mostly overhead.
Description: Size of bird:	~2/3-3/4 size of Common Loon
(Description:) Basic Shape:	Longish body (Longer than HOGR or EAGR--typical loon), sitting low in water.
(Description:) Overall Pattern:	Blackish back and grayish neck
(Description:) Bill Type:	Thin, sharp, upturned slightly
(Description:) Field Marks and Identifying Characteristics:	Very small loon sitting low in water. About 2/3-3/4 size of Common. Thin, upturned bill, longer than Horned Grebe. Dark back and grayish nape and back of neck. Whitish cheeks, but not as much white as a non-breeding adult. Head peaked in rear, similar to Horned Grebe. This bird was diving and moving quite a bit. Originally found in middle of lake and watched it as it swam toward the far shore and then toward the dam. Drove back to dam where we were able to get closer view in better light. (see photos)
Song or call & method of delivery:	none
Behavior:	Diving frequently. Moving around entire reservoir
Habitat:	Reservoir
Similar species and how were they eliminated:	Common Loon (of which there were many) is significantly larger with a much heavier bill and blockier head. Pacific Loon, which is also rare, though more expected than RTLO, is noticeably larger than RTLO with a straighter bill. PALO also tends to be darker overall with a dark neck. Horned grebe is non-breeding plumage is kind of similar with a relatively long body, whitish face, and peak at rear of head, but this RTLO had a longer bill and body, and sat lower in water than grebes usually do.
Previous experience with this & similar species:	Have seen many RTLO and COLO on both coasts, including less than a week ago off California coast. Have seen many PALO off California. While I sometimes have difficulty separating distant PALO from COLO, I don't usually have any trouble separating RTLO from PALO or COLO. Have also seen a number of HOGR in both the east and west, and don't normally confuse grebes with loons.
References consulted:	Sibley used to confirm age.
Description from:	Notes taken at the time of the sighting
Observer:	Michael Lester
Observer's address:
Observer's e-mail address:	**
Other observers who independently identified this bird:	Bryant Olsen
Date prepared:	24-25 October 2015
Additional material:	Photos
Additional_Comments:	Rare in Utah. Perhaps 14th or 15th state record? Appears to be first Summit County record.