Long-tailed Jaeger
Stercorarius longicaudus
This species is unmistakable as an adult, with grey back, dark primary wing feathers without a white "flash", black cap and very long tail. Adults often hover over their breeding territories. Juveniles are much more problematic, and are difficult to separate from parasitic jaeger over the sea. They are slimmer, longer-winged and more tern-like than that species, but show the same wide range of plumage variation. However, they are usually colder toned than Arctic, with greyer shades, rather than brown. This is the smallest of the skua family at 38–58 cm (15–23 in), depending on season and age.
ID text from Wikipedia, CC BY-SA 4.0
Pomarine Jaeger
Stercorarius pomarinus
This species ranges from 46 to 67 cm (18 to 26 in) in length, 110 to 138 cm (43 to 54 in) in wingspan and 540–920 g (1.19–2.03 lb) in weight. The upper limit of the length includes the elongated tail streamer of breeding adults, which is about 10 cm (3.9 in) in length. Identification of this jaeger is complicated by its similarities to parasitic jaeger and the existence of three morphs. Pomarine jaegers are larger than common gulls. They are much bulkier, broader-winged and less falcon-like than the parasitic jaeger, but show the same wide range of plumage variation.
ID text from Wikipedia, CC BY-SA 4.0
Where you might meet both
And 39 more countries.
Learn this pair in BeakBrain
Photo and call practice, free in any browser.
Play BeakBrainPhotos and recordings are credited to their authors under the licence shown. Full profiles: Long-tailed Jaeger and Pomarine Jaeger.