Sighting Record for Utah

Common name:	Arctic Tern
Scientific name:	Sterna paradisaea
Date:	10/13/26
Time:	10;55
Length of time observed:	around 1 minute
Number:	1
Age:
Sex:
Location:	American Fork Boat Harbor
County:	Utah
Latilong:
Elevation:
Distance to bird:	at closest 50-75 yards
Optical equipment:	vortex diamondback HD's, Leupold SX-4
Weather:	slight wind, overcast
Light Conditions:	diffused good light
Description: Size of bird:	sterna
(Description:) Basic Shape:	sterna
(Description:) Overall Pattern:	white, black, gray
(Description:) Bill Type:	Sterna bill
(Description:) Field Marks and Identifying Characteristics:	While the Storm petrel mayhem ensued, Esther and I were scoping from American Fork Boat Harbor with 10-15 or so people who had joined us after we reported Storm Petrels, SAGU, and Jaegers at our location. Many incredible birds were moving around all over the lake. Two such birds were Sterna. I first noticed and called out these birds as they flew distantly from east to west seemingly headed towards the North Shore. Not too much detail was picked up at this point, and we carried on scoping. A while later, I again noticed these and called them out, as they flew back, west to east, this time much closer. At first they flew towards us, again not picking up much detail, until they started heading more south and crossed in front of us maybe 50-75 yards out, and then away, until they were out of sight. During this, I had them in view the whole time, both with binoculars and scope, getting the best views in scope as they crossed in front of us, banking and showing their backs and upperwings a few times. A few people in the group had cameras, but between the mess of people, and a few trees off the point, were not able to get photos until the birds had gotten quite far, somewhat of a stressful mess, leaving us with essentially useless photos. However, with my excellent views, plus some discussion with the group, I write this report. While watching this bird, we noted rather strong carpal bars, and longish slim bill, causing me to call out COTE at one point. But as the bird banked away from us multiple times, a few things were consistent. This bird had white secondaries. Engrained into my memory is the overall look the wing and back pattern gave, which is of a pseudo Sabines Gull pattern - a dark M created by the carpals, darkish primaries, and white secondaries. This is how I described the birds' look thereafter - a faint sabine's wing on a Sterna. Members in the group agreed. I believe this bird was a juvenile considering a few things; it had some cold brown wash to the back, as well as the white secondaires, and an overall contrasty striking wing pattern, all features of a juvenile. The bird showed a dark bill, and a Cul de sac white forehead patch, no significant tail streamers, and fairly sharp thin black tipped primaries from underneath. Overall solidly in juvenile/nonbreeding plumage. I've spent some time looking through Macaulay library photos, where I was able to find many examples of ARTE across the globe which have retained some juvenile brownish plumage into October and through November. The second bird from memory was likely an adult, but that's some guessing, as I was locked onto the first bird mostly the whole time. Left as a / on my list, although quite possibly the ARTE that was subsequently later photographed at River Lane by another Birder. I believe I was able to observe the same bird again the next morning. Again we were there with the same hopes as the last, at the same spot scoping, when again a Sterna tern (this time one) flew into view, again heading east to west distantly towards the north shore. This bird showed some cold brown wash on the back, and most notably - white secondaries. I called this bird out, and as a few of us watched it, those same secondaries never appeared any darker than white. I can't personally speak much to bill size, as I was glued to the wing pattern during both observations. (see photos)
Song or call & method of delivery:
Behavior:	Sterna flight, buoyant, diving at the water.
Habitat:	open water
Similar species and how were they eliminated:	COTE - tough tough tough, and yet the most important factor being the secondaries. Its rather easy to sort through photos on Macaulay library and see that both arctic and Common Terns have notable variation in bill size and carpal bar contrast, a good example of this being the recent East Reservoir ARTE which also showed contrasty carpals.. And especially while viewed in flight, the bill size is tough to judge. Common Terns do not show white secondaries. Overall their wing pattern is darker, more washed out, with the darkest part of the wing being the carpals and the secondaries, especially in non-breeding. As a result, COTE does not show the look of a Sabines gull or M wing pattern in flight. If anything, I suppose more close to a non breeding Bonaparte's Gull wing, but again COTE overall have darker less contrasty wing patterns. It's why when reviewing this species, it's not the bill or carpals, or overall structure that are the reliable ID factors, but the wing pattern that is. Reference the COTE observed at Farmington bay on 10/27/25 that overall looked very ARTE, and yet once the wing pattern was revealed, was COTE. I believe the white secondaries, and overall M wing pattern shown, are enough, and the only legitimate way to rule out COTE in this case. Forster s Tern - the white cul de sac forehead and contrasty carpal bars rule out this species effectively.
Previous experience with this & similar species:	many many COTE, none with ARTE.
References consulted:	Sibley, Terns of North America, Macauley library
Description from:	Notes taken at the time of the sighting From photo(s) taken at the time of the sighting
Observer:	Mckay Olson
Observer's address:
Observer's e-mail address:	**
Other observers who independently identified this bird:	Esther Sumner, Kaleb Anderson, among others
Date prepared:	10/14/26
Additional material:	Photos
Additional comments:	https://ebird.org/checklist/S402136191