Inca Tern vs Slaty-backed Gull

Inca Tern

Larosterna inca

Medium219 gMarine

The Inca tern is roughly 39 to 42 cm (15 to 17 in) long and weighs between 180 to 210 g (6.3 to 7.4 oz). Its plumage is uniquely colored among terns; adults have a mostly dark, slate-gray body, with paler underwing coverts, and a slightly paler throat. A white stripe extends back from the base of the bill and fans out like a Salvador Dalíesque mustache as long, satiny feathers along the side of the neck. The trailing edge of the wing (the tips of the secondaries and the three inner primaries) are white. The tail is black, and moderately forked. Voice: The Inca tern is most vocal at its nesting colonies. Its calls include "raucous cackling notes" and "mewing"; the latter call has been likened to that of a kitten.

ID text from Wikipedia, CC BY-SA 4.0

Photo: Cristóbal Alvarado Minic from Cagua, Venezuela · CC BY 2.0

Slaty-backed Gull

Larus schistisagus

Large1.3 kgCoastal

It is tied with the yellow-footed gull for fourth-largest gull species, measuring 55–68.5 cm (21.7–27.0 in) in length, 132–160 cm (52–63 in) in wingspan, and 1.05–1.7 kg (2.3–3.7 lb) in weight. Among standard measurements, the wing chord is 40 to 48 cm (16 to 19 in), the bill is 4.8 to 6.5 cm (1.9 to 2.6 in), and the tarsus is 6 to 7.6 cm (2.4 to 3.0 in). It has a white head, belly, and tail with a dark slaty-gray back and wings with a broad white trailing edge. The wings and back are slightly darker than those of the western gull (Kodak grey scale 9.

ID text from Wikipedia, CC BY-SA 4.0

Photo: Original: ほくなん. This edit: MPF · Public domain

Photos and recordings are credited to their authors under the licence shown. Full profiles: Inca Tern and Slaty-backed Gull.