Like most other Hawks, this is a solitary bird, excepting during the breeding season, at the beginning of which it is seen in pairs. Their season of breeding is so very early, that it might be said to be in winter. I have seen the male caressing the female as early as the first days of December.
This species visits Louisiana during the winter months only; for although I have observed it mating then, it generally disappears a few days after, and in a fortnight later none can be seen. It is scarce in the Middle States, where, as well as in the Southern Districts, it lives along water-courses, and in the neighbourhood of the shores of the sea and inland lakes. I should think that they breed in the United States, having shot a pair in the month of August near the Falls of Niagara. It is extremely tenacious of life, and if not wounded in the wings, though mortally so in the body, it flies to the last gasp, and does not fall until life is extinct. I never saw one of them attack a quadruped, although I have frequently seen them perched within sight of squirrels, which I thought they might easily have secured, had they been so inclined.
Once when nearing the coast of England, being then about a hundred and fifty miles distant from it, in the month of July, I obtained a pair of these birds, which had come on board our vessel, and had been shot there. I examined them with care, and found no difference between them and those which I had shot in America. They are at present scarce in England, where I have seen only a few. In London, some individuals of the species resort to the cupola of St Paul's Cathedral, and the towers of Westminster Abbey, to roost, and probably to breed. I have seen them depart from these places at day dawn, and return in the evening.
The achievements of this species are well known in Europe, where it is even at the present day trained for the chase. Whilst on a visit at Dalmahoy, the seat of the Earl of Morton, near Edinburgh, I had the pleasure of seeing a pair of these birds hooded, and with small brass bells on their legs, in excellent training. They were the property of that nobleman.
These birds sometimes roost in the hollows of trees. I saw one resorting for weeks every night to a hole in a dead sycamore, near Louisville in Kentucky. It generally came to the place a little before sunset, alighted on the dead branches, and in a short time after flew into the hollow, where it spent the night, and from whence I saw it issuing at dawn.