Chapter IV: GENUS ROSTRHAMUS. Lesson, Traité d’Orn., I. p. 55. (1831.)

Bill long, very slender, hooked, and sharp at the tip; wings long, pointed; tail rather long, emarginate; tarsi and toes rather long; claws very long, slender, acute. The present is the only species.

1. Rostrhamus sociabilis. (Vieill.) The Hooked-billed Hawk.
Herpetotheres sociabilis. Vieill., Nouv. Dict., XVIII. p. 318.
(1817.)
Cymindis leucopygius. Spix, Av. Bras., I. p. 7. (1824.)
Rostrhamus niger. Less., Traité, I. p. 56. (1831.)
“Falco hamatus. Illiger.” Lesson, as above.

Temm., Pl. col. I. 61, 231; Spix, Av. Bras., I. pl. 2; Guerin, Mag. de
Zool., 1834, pl. 20.

Adult. Tail at base, and under tail-coverts, white; all other parts
black. Naked space before the eye yellow, which is also the color of
the feet; bill and claws black. Tail usually tipped with
pale-cinereous. Younger. Throat and line over and behind the eye
yellowish-white; general plumage brownish-black, mixed with
yellowish-white on the under-parts of the body. Young. Forehead—stripe
behind the eye and throat reddish or ferruginous-white; upper-parts
brown, many feathers edged with pale-ferruginous; under-parts
yellowish, with longitudinal stripes of black; tail at tip and base,
and under tail-coverts, yellowish-white. Legs yellowish-green.

Dimensions. _Female_—total length (of skin), 16 inches; wing, 14;
tail, 7½ inches. _Male_—smaller.

Hab. Florida (Mr. Harris, Dr. Heermann). Spec. in Mus. Acad., Philada.

Obs. This bird is remarkable for its slender and hooked bill, unlike that of any other Falcon. It is well known as a South American bird, and was first noticed in Florida by Mr. Edward Harris; subsequently by Dr. Heermann. Both these gentlemen having obtained specimens of young birds, it is probably a constant resident of that State.