Verification of Unusual
Sight Record
For Utah
Rec. # 2021-48
| Common name: |
Parasitic Jaeger |
| Scientific name: | Stercorarius parasiticus |
| Date: | 9/3/2021 |
| Time: | 10:50am |
| Length of time observed: | 2 hours,45 minutes |
| Number: | 1 |
| Age: | juvenile |
| Sex: | ? |
| Location: | Decker Lake, West Valley City |
| County: | Salt Lake |
| Latilong: | 40.7114011,-111.9488016 |
| Elevation: | 4300ft |
| Distance to bird: | 20m at closest |
| Optical equipment: | Nikon 10x42 binoculars, Kowa spotting scope |
| Weather: | Clear, sunny and calm |
| Light Conditions: | Moderate, some smoke made light hazy, also midday light was harsh |
| Description: Size of bird: | smaller than nearby gulls except Franklin's |
| (Description:) Basic Shape: | gull like |
| (Description:) Overall Pattern: | uniformly dark brown |
| (Description:) Bill Type: | thin but hooked at tip |
|
(Description:)
Field Marks and Identifying Characteristics: |
juvenile intermediate dark morph. Short but pointed R1 tail feathers, rusty
edging to feathers and some rust in undertail coverts, long bill with small nail
less than 1/2 length of bill. 5 primaries show white shafts on upper side.
Smaller than California and Ring-billed Gulls, but did chase gulls very swiftly
and acrobatically several times, interestingly seemed to target Ring-billed
Gulls which were least common gull in the flock. (see photos) |
| Song or call & method of delivery: | None heard |
| Behavior: | Initially seen just swimming on the water, but about every 10 to 15 minutes would get up and go after the gull flock, single out a target, usually a Ring-billed Gull, and chase it around for a few minutes, then would settle back on the water or shore. At one point soared up with the flock very high, but then dropped back down to the lake |
| Habitat: | freshwater pond |
| Similar
species and
how were they eliminated: |
Long-tailed Jaeger-bill should be shorter with nail making 1/2 of length, white
shafts to primaries on upper side only on 2 outer most primaries, longer but
blunt R1 tail feathers. Usually lack rusty edging to feathers, especially in
undertail coverts Pomeraine Jaeger-overall larger and bulkier, similar is size to Ring-billed Gulls. Bigger more prominent nail on bill. R1 tail feathers blunt not pointed. Usually lack rusty edging on undertail coverts Photos shared with Skuas and Jaegers of the word Facebook group, unanimous consensus Parasitic Jaeger/Arctic Skua |
| Previous
experience with this & similar species: |
Yes, many in Alaska last month, several in Washington state last Autumn, and 3 in Utah over the past 7 years. I've also seen many of all other Jaeger species, including in Utah 2 LTJA and 1 POJA |
| References consulted: | Sibley app |
| Description from: | From photo(s) taken at the time of the sighting |
| Observer: | Bryant Olsen |
| Observer's address: | 84102 |
| Observer's e-mail address: | ** |
| Other observers who independently identified this bird: | Matt Pendleton, Kendall Watkins, Quin Diaz, David Wheeler, Mike Malmquist, Max Malmquist, Lauri Taylor, Vivian Schneggenburger view it with me, many others since |
| Date prepared: | 9/4/21 |
| Additional material: | Photos |
| Additional comments: | eBird checklist: https://ebird.org/checklist/S94126456 |