I have found a greater number of barren females in this species than in any other; and to this I in part attribute their predominance over the males. The food of the Marsh Hawk consists of insects of various kinds, especially crickets, of small lizards, frogs, snakes, birds, principally the smaller sorts, although it will attack Partridges, Plovers, and even Green-winged Teals, when urged by excessive hunger. The only instance in which I have seen this bird carry any prey in its talons on wing, happened on the 2d of April 1837, at the south-west Pass of the Mississippi, when I was in company with Edward Harris, Esq. and my son John Woodhouse. A Marsh Hawk was seen to seize a bird on its nest, perhaps a Marsh Wren, Troglodytes palustris, and carry it off in its talons with the nest! A pair were hovering over the marsh during the whole of our stay, and probably had a nest thereabout. It is rather a cowardly bird, however, for on several occasions, when I was in the Floridas, where it is abundant, I saw it chase a Salt-water Marsh Hen, Rallus crepitans, which courageously sprung up, and striking at its enemy, forced it off. My friend John Bachman has frequently observed similar occurrence in the neighbourhood of Charleston. Whenever it seizes a bird on wing, it almost at once drops to the ground with it, and if in an exposed place, hops off with its prey to the nearest concealment.
In autumn, after the young have left their parents, they hunt in packs. This I observed on several occasions when on my way back from Labrador. In Nova Scotia, on the 27th of August, we procured nearly a whole pack, by concealing ourselves, but did not see an adult male. These birds are fond of searching for prey over the same fields, removing from one plantation to another, and returning with a remarkable degree of regularity, and this apparently for a whole season, if not a longer period. My friend John Bachman observed a beautiful old male which had one of its primaries cut short by a shot, regularly return to the same rice-field during the whole of the autumn and winter, and believes that the same individual revisits the same spot annually. When satiated with food, the Marsh Hawk may be seen perched on a fence-stake for more than an hour, standing motionless. On horseback I have approached them on such occasions near enough to see the colour of their eyes, before they would reluctantly open their wings, and remove to another stake not far distant, where they would probably remain until digestion was accomplished.
I have never seen this species searching for food in the dusk. Indeed, in our latitudes, when the orb of day has withdrawn from our sight, the twilight is so short, and the necessity of providing a place of safety for the night so imperious in birds that are not altogether nocturnal, that I doubt whether the Marsh Hawk, which has perhaps been on wing the greater part of the day, and has had many opportunities of procuring food, would continue its flight for the sake of the scanty fare which it might perchance procure at a time when few birds are abroad, and when quadrupeds only are awakening from their daily slumber.
Wilson must have been misinformed by some one unacquainted with the arrival and departure of this species, as well as of the Rice Bird, in South Carolina, when he was induced to say that the Marsh Hawk “is particularly serviceable to the rice-fields of the Southern States, by the havoc it makes among the clouds of Rice Buntings that spread such devastation among the grain, in its early stages. As it sails low, and swiftly, over the surface of the field, it keeps the flocks in perpetual fluctuation, and greatly interrupts their depredations. The planters consider one Marsh Hawk to be equal to several Negroes for alarming the Rice Birds.” Now, good Reader, my friend John Bachman, who has resided more than twenty years in South Carolina, and who is a constant student of nature, and perhaps more especially attentive to the habits of birds, informs me that the Marsh Hawk is proportionally rare in that State, and that it only makes its appearance there after the Rice Birds have left the country for the south, and retires at the approach of spring, before they have arrived.
European writers have generally considered our Marsh Hawk as larger than their Circus cyaneus; but this opinion must have originated from a want of specimens for comparison, and perhaps also a want of books on which one might depend. Were all ornithological works characterized by the accuracy and detail to be found in those of my friend William Macgillivray, the case might be different. The measurements which he has taken from recent specimens correspond with those which I also have taken from individuals newly killed, as nearly as is usual in birds of other species. Indeed, should you measure as accurately as possible a hundred specimens of any bird as large as our Marsh Hawk, I am persuaded you would not find many of them to agree in all their proportions. Instead of the American exceeding the European bird in size, I think it will generally be found to be as nearly equal as possible.
Falco cyaneus and F. pygargus, Linn. Syst. Nat. vol. i. p. 126.
Falco cyaneus, Lath. Ind. Ornith. vol. i. p. 39.—Ch. Bonaparte, Synopsis of Birds of United States, p. 33.
Marsh Hawk, Falco uliginosus, Wils. Amer. Ornith. vol. vi. p. 67, pl. 1, fig. 1., young female.
Falco cyaneus, Ch. Bonaparte; Amer. Ornith. vol. ii. p. 30, pl. xi. fig. 1., male.
Buteo (Circus) cyaneus ? var ? Americanus, American Hen-Harrier, Richards. and Swains. Fauna Bor.-Amer. vol. ii. p. 55.