The Black-shouldered Hawk appears to give a decided preference to low lands, not distant from the shores of the Atlantic. On our way toward the Texas, several of these birds were seen over the large marshes, flying at a small elevation, and coursing in search of prey, much in the manner of the Hen-harrier or Marsh Hawk, but all evidently bent on proceeding to the eastward. Whether this species winters there or not, I am unable to say, but that some remain all the year in Florida, and even in South Carolina, I am quite confident. The difference between the food of this species and that of the Mississippi Kite is surprising to me. I have never seen the latter seize any bird, whereas the Black-shouldered Hawk certainly does so, as in the stomachs of two individuals which I examined were remains of birds as well as of coleopterous insects. These two birds agree nearly with the description of the one procured by Mr TITIAN PEALE, excepting in the length of the wings, which in them and in several others that have come under my notice, have their tips fully an inch shorter than the end of the tail. A breeding female differed from the rest in having the eyes dull yellowish-red; the tail-feathers had all been ash-grey, all the primaries were edged with white, and many of the secondaries were still of a light brownish-grey; the black spots under the wings were smaller than usual; the abdomen was also tinged with brownish-grey. I am therefore of opinion, that these birds undergo as many changes of plumage as the Mississippi Kite. BLACK-WINGED HAWK, FALCO MELANOPTERUS, _Ch. Bonaparte_, Amer. Orn. vol. ii. pl. 11. fig. 1. Female. FALCO MELANOPTERUS, _Ch. Bonaparte_, Synopsis of Birds of United States, p. 31. FALCO DISPAR, _Temm._ _Ch. Bonaparte_, Synopsis. Append, p. 435. Adult Male. Plate CCCLII. Fig. 1. Bill short, broader than deep at the base, with the gape very wide. Upper mandible with the cere covered at the base with bristly feathers, the dorsal line convex and declinate to the end of the cere, then curved downwards in about the third of a circle, the sides at the base sloping towards the end convex and erect, the sharp edges with a distinct festoon, the tip narrow and acute. Lower mandible with the angle very wide and long, the dorsal outline very short, ascending and slightly convex, the sharp edges inflected, the tip obliquely truncate and narrow. Nostrils elliptical, rather large, in the fore part of the cere.