Sighting Record for Utah

Common name:	Wedge-rumped Storm-Petrel
Scientific name:	Hydrobates tethys
Date:	10/12/26
Time:	8:40ish
Length of time observed:	30 mins
Number:	5-8
Age:
Sex:
Location:	River Lane - Sandy Beach
County:	Utah
Latilong:
Elevation:
Distance to bird:	100 yards or so at closest
Optical equipment:	Vortec diamondbacks HD, Leupold SX-4
Weather:	windy, raining.
Light Conditions:	excellent, diffused light.
Description: Size of bird:	notably larger than Barn Swallows around
(Description:) Basic Shape:	long winged, bulky, stubby
(Description:) Overall Pattern:	dark, some blonde, white
(Description:) Bill Type:	tiny tubenose
(Description:) Field Marks and Identifying Characteristics:	The birds that started it all. What a wild week. After scanning River Lane - Sandy Beach, we walked back to begin looking for passerines. I decided to take a look back and check some gulls that had amassed while we walked back. Directly behind them I saw TWO storm petrels. I immediately recognized them as storm petrels due to the flight style, and walking on water behavior, which turned out to be something more like landing or splashing down on the water. They were not far from the shoreline. I yelled thats a ******* storm petrel and quickly got some video through scope. Once I had some footage, we sprinted for the shoreline. Never have I ever run so hard while birding. Once we arrived at the distant shoreline, I was able to get Esther on the birds, and started filming digiscope footage. In the field, we stressfully tried to ID them by taking in field notes. The birds distance themselves, and soon, 2 turned into 5-8. Tough to say just how many as they were zooming around the lake. We got the word out to their presence, and within 20-30 minutes, we were hearing of other people going out and seeing them all over Utah lake, as well as other bodies of water. We left the scene headed to Lincoln Point, still unsure of ID. but with hopefully plenty of footage to figure it out later. Once at Lincoln point, we were able to watch another individual for a very long time, with 20-30 people onsite. At which point we all landed on Wedge Rumped Storm Petrel as the correct ID. Having gone through my own footage, I was able to pull enough detail to conclude the River Lane birds were likely the same species. These storm petrels were direct in flight, but also frequently bouncy. Somewhat of a rhythm of several rapid wingbeats, paired with a few slower deeper wing beats. These birds showed extensive white rumps, so extensive, that the white almost reached the end of the tail. They seem to show somewhat forked tails at rest, but more typically wide straight tails as they were consistently fanning in flight. They showed strong carpal bars or more accurately greater coverts, that were blonde. Otherwise, these birds were dark. The dark backs of these birds ended in a straight line transitioning to the white rumps. What an amazing couple of days. I had no anticipation of finding any south American or pelagic storm related birds even after the extensive downpour from the day before. (see photos)
Song or call & method of delivery:
Behavior:	bouncy, flighty, constantly landing on the water
Habitat:	Open water
Similar species and how were they eliminated:	Wilsons Storm Petrel - this was relatively easy to rule out after some time due to the significantly more extensive white rumps, the lack of leg projection beyond the tail, and the lack of the pattering on water behavior that a WISP would show. Our birds certainly danced and landed on the water frequently, but did not appear to be dragging or pattering their feet across the water. Townsend s Storm Petrel - certainly one of the harder to rule out. Sibley shows these birds as looking near identical, however looking through Ebird photos, they are more different. TOSP would show less extensive white rumps that never come as close to reaching the end of the tail. The dark back of a TOSP should extend beyond the wings reaching further into the white rump, overall creating a more minimal white rump. Leach s Storm Petrel - Another tough contender, but again a species that would have a much less extensive white rump, as well as typically showing a more extensive dark back working into the rump, creating a sort of round spur look down into the rump. Our birds consistently showed squared back to rump transitions. Least and Black Storm petrel - any white in the rump effectively rules these species out, among other things.
Previous experience with this & similar species:	none
References consulted:	sibley, Macauley Library and many
Description from:	From: Notes made later 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, Bryant Olsen, Max Malmquist, and many many many others.
Date prepared:	10/19/26
Additional material:	Photos
Additional comments:	https://ebird.org/checklist/S401884505