Mr. Dresser found this Vulture about equally common with the R. aura on the Lower Rio Grande, but much less common near San Antonio. He usually found the two species in company, attended also by the Polyborus auduboni and Craxirex harrisi. They were found breeding among the rocks at Systerdale, where they were said to be the only species found.
Dr. Coues did not meet with any in Arizona, nor were any taken on the survey of the Mexican boundary. In South Carolina he considered it chiefly confined to the lower country, while the C. aura is more generally distributed over the State. The two meet together freely, and as they circle about in each other’s company they afford an excellent opportunity of noticing the great differences in their mode of flight and in the outline of their bodies and wings. On the other hand, Wilson, Ord, and others deny that the two kinds live together.
In the Southern Atlantic cities, especially Charleston and Savannah, the Black Vulture is a semi-domestic bird, and is very abundant. It is also to be found in the interior, but is neither so common nor so tame.
The Catharista atratus is said to be much more sensitive to cold than the aura, and when the weather is at all unfavorable they cower around the tops of chimneys to enjoy the heat. Though tolerated and even protected by law, their filthy habits render them a source of annoyance to those whose houses they frequent. Their value as scavengers and the services they render in the removal of offal render them almost a necessity in Southern cities.
Both in their mode of flight and in their movements upon the ground this species differs materially from the Turkey-Buzzard. The latter walks steadily while on the ground, and when it mounts does so by a single upward spring. The Black Vulture is ill at ease on the ground, moves awkwardly, and when it essays to fly upward takes several leaps in a shuffling sidelong manner before it can rise. Their flight is more labored, and is continued by flapping several times, alternating with sailing a limited distance. Their wings are held at right angles, and their feet protrude beyond their tail-feathers. In all these respects the differences between the two birds are very noticeable, and plainly mark the species.
Mr. Audubon states that at the commencement of the mating-season, early in February, the gesticulations of the males are very conspicuous. They strut in the manner of a Turkey-cock, open their wings, lower their heads, and utter a puffing sound that is anything but musical.
Alexander Wilson describes with great minuteness a scene he witnessed near Charleston, where the carcass of a horse was devoured by these birds, the ground for hundreds of yards around being black with them. He counted at one time two hundred and thirty-seven, while others were in the air flying around. He ventured within a few yards of the horse without their heeding his presence. They frequently attacked one another, fighting with their claws and striking with their open wings, fixing their claws in each other’s head. They made a hissing sound with open mouths, resembling that produced by thrusting a red-hot poker into water, and occasionally a snuffling noise, as if clearing their nostrils. At times one would emerge with a large fragment, and in a moment would be surrounded by several others, who would tear it in pieces and soon cause it to disappear.
The Black Vulture breeds on or near the ground in the same manner as the Turkey-Buzzard, in hollow logs, decayed trunks of trees, and stumps, and also without this protection, the bare earth only being made use of. It is said to make no nest. The eggs seldom, if ever, exceed two in number. These are greater, both in their length and capacity, than those of the Turkey-Buzzard, although the measurements of the birds themselves would seem to show the latter to be apparently the larger bird. The average weight of the Black Vulture’s egg, however, is about one pound, or fifteen per cent greater than that of the Buzzard. Three from Charleston, Galveston, and the Rio Grande furnish the following measurements: 3.81 inches by 1.94; 3 by 2.06; 3.06 by 1.94. The principal difference between the eggs of this and the preceding species is in regard to their size. Their ground-color is the same, or nearly the same,—a yellowish-white or cream-color, almost never a pure white, and only in exceptional cases. The eggs are more elongate in their shape, and the blotches are usually larger. These are of a dark reddish-brown, confluent, and chiefly distributed around the larger end. There are also markings, smaller and less frequent, of lilac and purplish-drab, similar to those noticed in the eggs of C. aura. An egg from the Rio Grande is marked with small spots of reddish-brown and obscure lilac, equally distributed over the whole surface on a ground of cream-color.
Mr. Audubon is positive that this Vulture never breeds in trees, and that they never build any nest, but deposit their eggs on the ground, on a dead log, or in a hollow tree. Twenty-one days are required for hatching their eggs, on which the male and female sit by turns and feed each other. The young are covered with a light cream-colored down, and are fed with regurgitated food, in the manner of Pigeons. As soon as they are able, they follow their parents through the woods, at which period their entire head and neck, which afterwards become bare, are covered with feathers.