Habits. The Marsh Hawk is one of the most widely distributed birds of North America, breeding from the fur regions around Hudson’s Bay to Texas, and from Nova Scotia to Oregon and California. It is abundant everywhere, excepting in the southeastern portion of the United States. Sir John Richardson speaks of it as so common on the plains of the Saskatchewan that seldom less than five or six are in sight at a time (in latitude 55°). Mr. Townsend found it on the plains of the Columbia River and on the prairies bordering on the Missouri. The Vincennes Exploring Expedition obtained specimens in Oregon. Dr. Gambel and Dr. Heermann found it abundant in California. Dr. Suckley’s party obtained specimens in Minnesota; Captain Beckwith’s, in Utah; Captain Pope, Lieutenant Whipple, and Dr. Henry, in New Mexico; and Lieutenant Couch, in Tamaulipas, Mexico. Dr. Woodhouse met with it abundantly from the Mississippi River to the Pacific Ocean, throughout the summer, showing conclusively that it breeds in those different sections of country. De la Sagra, Lembeye, and Dr. Gundlach, all give it as a bird of Cuba, but not as breeding there.
Dall records it as very rare on the Yukon, and an occasional summer visitor only at St. Michael’s, where an individual was killed as late as November. Donald Gunn states that it makes its appearance in the fur countries about the opening of the rivers, and departs about the beginning of November. It preys upon small birds and mice, is very slow on the wing, flies very low, and in a manner very different from all other kinds of Hawks.
In Nova Scotia it is very abundant, and is very destructive of young game. Mr. Downes regards it as an indiscriminating feeder upon fish, snakes, and even worms. He took two green snakes from the stomach of one of them.
Circus hudsonius (male and female).
Mr. Dresser found them abundant throughout the whole country east of the Rio Nueces at all seasons of the year. They were more abundant in full blue plumage than elsewhere. Near San Antonio he met with them on the prairies, where they feed on the small green lizards which abound there, and which they are very expert in catching. Dr. Coues mentions them as very abundant in Arizona. Dr. Kennerly met with them on both sides of the Rio Grande wherever there was a marsh of any extent. Flying near the surface, just above the weeds and canes, they round their untiring circles hour after hour, darting after small birds as they rise from cover. Pressed by hunger, they will attack even wild Ducks. Dr. Kennerly also observed them equally abundant in the same localities in New Mexico. Dr. Newberry mentions finding this Hawk abundant beyond all parallel on the plains of Upper Pitt River. He saw several hundred in a single day’s march.
In Washington Territory both Dr. Suckley and Dr. Cooper found this Hawk abundant throughout the open districts, and especially so in winter. Dr. Cooper found it no less common in California, and among several hundreds saw but two birds in the blue plumage. Near Fort Laramie he found it no less common, but there, at least one half were in the blue plumage. From this he infers that the older birds seek the far interior in preference to the seaboard.
Mr. Allen mentions it as common in winter about the savannas in Florida, and Mr. Salvin states that it is a migratory species in Guatemala. It occurred in the Pacific Coast Region, and examples were also received from Vera Paz.
In evidence of the nomadic character of the Marsh Hawk it may be mentioned that specimens asserted to be of this species are in the Leyden Museum that were received from the Philippines and from Kamtschatka.
In Wilson’s time this Hawk was quite numerous in the marshes of New Jersey, Pennsylvania, and Delaware, where it swept over the low grounds, sailing near the earth, in search of a kind of mouse very common in such situations, and was there very generally known as the Mouse Hawk. It is also said to be very serviceable in the Southern rice-fields in interrupting the devastations made by the swarms of Bobolinks. As it sails low and swiftly over the fields, it keeps the flocks in perpetual fluctuation, and greatly interrupts their depredations. Wilson states that one Marsh Hawk was considered by the planters equal to several negroes for alarming the Rice-birds. Audubon, however, controverts this statement, and quotes Dr. Bachman to the effect that no Marsh Hawks are seen in the rice-fields until after the Bobolinks are gone. Dr. Coues, on the other hand, gives this Hawk as resident throughout the year in South Carolina.