Prairie Rattlesnake

Crotalus confluentus, (Say)

Colouration.—Greenish yellow, or olive, with a row of large, round and well separated blotches of brown upon the back. There is usually a smaller and less distinct row of blotches on the side. The blotches of the back have a narrow, dark margin and outside of this is usually a narrow margin of white or yellow. Toward the tail the blotches fade into obscure transverse bands.

Dimensions.—Total Length of an adult, female specimen from Wyoming . . . . . 38 1/2 inches.

Distribution.—The range is quite extensive and the writer quotes the careful summing up of the distribution as given by Dr. Leonhard Stejneger: ("The Poisonous Snakes of North America." Report of the U. S. National Museum for 1893, pp. 337-487.)

Habits.—In its general demeanour toward man, this very abundant species of the plains is a vicious reptile. Though it never actually attacks, it puts up such a show of fight that the attitude is far from reassuring to the uninitiated in the ways of rattlers. None of the rattlesnakes, large or small, throw as much energy into the fighting coil as this species. When surprised it flings its body into circular formation, raises the neck some distance from the loose coils in the form of a sharply oblique bow and jabs hurriedly at the enemy. So energetic is the stroke that the writer has seen a snake slide forward several inches. These antics soon give way to a good-natured laziness in captivity. Captive specimens are hardy and fond of mice and birds. A specimen in the writer's collection became so tame it would glide to the door of the cage and take a dead mouse from his fingers; the operation was in no way dangerous as the snake in crawling to the coveted morsel advanced with straightened neck and was unable to "strike." The mouse was seized very gently and at once swallowed. Mr. Walter Ralston, to whom the writer is indebted for many interesting snakes, had several tame specimens. They were in possession of their fangs, but Mr. Ralston handled them like his harmless serpents and with never a show of bad temper on the rattlers' part; he jokingly remarked that his snakes had forgotten how to rattle as they had not used their caudal appendages for many months.

Colouration.—Very similar to the prairie rattlesnake. The ground-colour is gray, pale brown or greenish. On the back are large, rounded spots, well separated and narrowly bordered with black; toward the tail these blotches fuse into the shape of transverse bands; the tail is more strongly barred with the darker colour than that of the other species.

Dimensions.—An adult specimen, from Beaver County, Utah, and having a rattle consisting of five uniform segments, showed the following measurements:

Distribution.—The Pacific region, from southern British Columbia to southern California. Also occurs in Idaho, Nevada and Utah. It inhabits mountainous regions to an altitude of 11,000 feet.

Habits.—Similar to the prairie rattlesnake. It is hardy in captivity.

The average snake of this species is of moderate size, and not so stout of body as most rattlesnakes. Occasional specimens are six feet long.

The head markings are important as they may alone be employed in distinguishing the species from the Pacific Rattle-snake, which it closely resembles.

There is a dark band from beneath the centre of the eye to the angle of the mouth. This is bordered both in the front and the rear by a yellow stripe, the front stripe being narrow--the width of a single scale-row. In comparing the heads of these species it will be noted that the Pacific Rattlesnake has the dark band commencing behind the centre of the eye, and the forward pale stripe much wider--about the width of two scales.

The eye plates are usually marked with two white or yellow lines, which run together and form a sharp point at the outer margin.

Length of Tail, ex. rattle . . . . . 2 3/4 inches.

Greatest Diameter . . . . . 1 1/2 inches.

Width of Head . . . . . 1 1/4 inches.

Length of Head . . . . . 1 5/8 inches.

Number of "rattles"--7 uniform segments.

"Broadly speaking, the Prairie Rattlesnake occupies the area bounded in the East by the ninty-sixth meridian and the Upper Missouri Valley; by the main divide of the Rocky Mountains in the West; by the thirty-third parallel in Texas and the Mexican boundary further west in the South; and by the fiftieth parallel in the North. In the Northeast its distribution appears to be limited by the watershed between the Missouri and the Red-River of the North, according to Dr. Coues (Bull. Geol. Surv. Terr. IV, 1878, p. 267), who collected numerous specimens along the Canadian border between this watershed and the crest of the Rockies. He also states that it is to be considered fairly common in the region of the Upper Missouri and Milk River and some of their Northern tributaries; its range thus extending some distance into the British Possessions, where Mr. James M. Macoun informs me that it is most abundant from Medicine Hat, on the Saskatchewan to the boundary."