European Storm Petrel vs Fork-tailed Storm Petrel

European Storm Petrel

Hydrobates pelagicus

Small25 gMarine

The storm petrel is a small bird, 14–18 cm (5.5–7.1 in) in length with a 36–39 cm (14–15 in) wingspan. It weighs 20–38 g (0.71–1.34 oz), with an average of 28 g (0.99 oz). It is square-tailed and has all-black plumage except for a snow-white rump that extends to the sides of the tail base and a broad white band on the under wings. Juveniles in fresh plumage can also show a narrow white bar on the upper wing. The plumage becomes dark brown rather than black as it becomes worn. Voice: In its display flight, the storm petrel gives a call consisting of eight or more repetitions of a fast ter-CHICK sounds ending in a trill (rapid alternation of notes). This chattering, staccato call is highly variable in pitch, stress, and length. Both sexes make the call, which is used as an advertisement for a mate, for pair recognition, and in the nuptial flight.

ID text from Wikipedia, CC BY-SA 4.0

Photo: Lucy Keith-Diagne · CC BY 4.0

Fork-tailed Storm Petrel

Hydrobates furcatus

Small60 gMarine

The fork-tailed storm petrel is small seabird that is 20 cm in length with a wingspan of 46 cm. Its foraging behaviour resembles other storm petrels, where it flies with short, stiff wingbeats close to the surface of the water. Despite its name, the forked tail in this bird is not always visible. The distinguishing feature of fork-tailed storm petrels is their overall bluish-gray plumage. They generally have a paler underside, which contrasts the darker colours under their wings. They also have a dark gray forehead, a black ear patch, and a small, black bill.

ID text from Wikipedia, CC BY-SA 4.0

Photo: C. Schlawe · Public domain

Photos and recordings are credited to their authors under the licence shown. Full profiles: European Storm Petrel and Fork-tailed Storm Petrel.