An unusually graceful, dove-like gull species, Bonaparte’s gull (Larus philadelphia) is one of the smallest gulls in North America. It is a striking bird, especially during the breeding season when the adult has a uniformly sooty-black ‘hood’ covering the face and crown, with contrasting white crescents around the eyes (2).
Bonaparte’s gull is light slate-grey on the shoulders, back and wings, and a distinct black line runs along the wing’s trailing edge (2) (3) (4). The underparts and the tail are white (2), except for the grey neck and sides of the breast which merge with the grey upperparts (4). During the breeding season the breast may show a subtle rosy-pink tinge (2). This species has a black, spike-like bill which is longer and more slender in males than in females (2) (3) (4). The legs are orange-red to pinkish (2) (4).
During the non-breeding season, Bonaparte’s gull lacks the distinctive black hood. Instead, the head is entirely white, although it often has dark smudges on the top and in front of the eye, as well as a prominent, dark, isolated ear-spot behind the eye (2) (3) (4).
Juvenile Bonaparte’s gulls have a greyish-brown head and upperparts, often with a dark cap and ear-spot (4). The head may be partly mottled white during the summer (2). The wings of juvenile gulls are pale grey on the upperparts and have a prominent brownish-black bar across the wing, a narrow dark line around the wing tip, and strongly contrasting outer primaries. There is a narrow black band at the tip of the tail (2).
Although currently placed in the genus Larus, recent genetic and taxonomic studies have suggested that Bonaparte’s gull may in future be moved to the genus Chroicocephalus (2) (5).
- Mouette de Bonaparte.
- Length: 28 - 30 cm (2)
- Wingspan: 90 - 100 cm (2)