Mr. Ridgway obtained two eggs of this Hawk at Mount Carmel, Ill., on the 6th of March, the nest having been commenced early in February. It was placed on the summit of a black-gum tree (Nyssa multiflora), and rested upon the topmost branches, about ninety feet from the ground. It was lined with corn-husks, gathered from a field close by. The eggs (No. 12,740, S. I. Collection) measure, respectively, 2.45 and 2.50 in length, by 1.95 and 2.00 in breadth. Their color is plain bluish-white, entirely free from markings of any kind.
In California, the var. calurus is stated to be common in all parts of the State not destitute of trees, and to reside permanently wherever found, pairing only during the breeding-season. They prey upon hares and other small quadrupeds, upon smaller birds, and upon reptiles. Dr. Cooper states that at times, when food is plenty, they become excessively fat. They are known to occasionally seize a fowl from the farm-yard. During the middle of the day, in the cold weather, they are said to soar very high in the air, and occasionally to disappear also in the manner of their eastern relatives, the Buteo borealis. They are said to be abundant and resident species in Washington Territory, having been found by Dr. Suckley quite numerous at Puget Sound, but scarcer on the Upper Columbia, east of the Cascade Mountains. It seems to be more daring than is common with the borealis, for Dr. Suckley states that while he was stationed at Fort Steilacoom he noticed that the poultry-yards were as much harassed by this Hawk as by the Goshawk, not hesitating to seize poultry from the very doors of the dwelling-houses.
Dr. Kennerly states that this Hawk was met with by him between the coast of Texas at Indianola, and the Rio Grande at El Paso del Norte. It seemed to feed indifferently upon reptiles, particularly lizards, and the smaller quadrupeds and birds.
Dr. Cooper states that the nests of this species are numerous in the valleys and on the lower mountains of California. They are generally built in the forks of a sycamore or other large trees, and formed of twigs pretty finely constructed, and with a very distinct cavity. Eggs, taken by Dr. Cooper near San Diego, were laid about the 20th of March, and were three in number. They measured 2.28 by 1.76 inches, were of a dull yellowish-white, with faint brown spots. While Dr. Cooper was climbing to the nest, the old birds darted towards him from a neighboring bluff, but when within a few feet of his head they turned away and did not attempt to make an assault.
Two eggs belonging to the variety calurus were obtained by Mr. E. Samuels near Petaluma, Cal., in 1856; measure 2.31 inches in length by 1.87 in breadth. The shape of one egg is an almost exact ovoid, slightly tending to a spheroid, one end being hardly perceptibly larger than the other. Its ground-color is a very light buff, the spottings and markings giving to it the effect of a yellowish-white. It is marked over the entire surface with blotches, dashes, and lines of a light tint of a brown tending to vandyke. These are mixed with markings of a lighter purplish-brown. The markings, of both shades, are chiefly oblong in shape, and run with the length of the egg. They bear no resemblance to any eggs of the B. borealis that I have ever seen, and are unlike those of other Hawks so far as I am aware. It was built on the top of a large evergreen-oak, at least seventy feet from the ground, and was constructed entirely of large, coarse sticks, lined with a few stray feathers. The male bird was shot as it flew from the nest, which was so hidden by the thick branches that it would have escaped detection.
The black form of this species was first described by Mr. Cassin as Buteo calurus, in 1855, from a specimen procured by Dr. Henry near Fort Webster, New Mexico. In this plumage it was afterwards met with by Mr. Emanuel Samuels, near Petaluma, in California, who found it breeding, and was fortunate enough to secure the parent bird on its nest.
The nest was built near the top of an evergreen-oak, at the height of about sixty feet from the ground, and contained two eggs just on the point of hatching. It was constructed of sticks, and was lined with moss. Both birds were about the spot. The male bird, manifesting much more courage than his mate in resistance to the intruders, was shot. The female was wounded, but escaped.
One of these eggs measures 2.25 inches in length by 1.79 in breadth. Its capacity is considerably less than that of the specimens just described; its shape is a much more oblong-oval; one end is evidently more pointed than the other. Its ground-color is a dirty cream-white, covered, chiefly at the larger end, with blotches and smaller markings of a dark shade of a brown almost exactly corresponding with that known as vandyke-brown, with smaller markings and spottings of a lighter shade of the same. The latter are distributed at intervals over its entire surface.
A nest, found by Mr. Xantus near Fort Tejon, is stated by him to have been found in a swamp. It was built in a water-oak, was about fifteen feet from the ground. The nest was very large and was built of coarse sticks. It contained four eggs.