From the popular point of view the Rattlesnakes are the most interesting of the American serpents. From an actual standpoint, they are the most important of all the reptiles inhabiting the United States, for among them we find by far the greater number of our poisonous snakes, and species that are next to none in point of deadliness, of the dangerous family of Vipers--the thick-bodied poisonous serpents--that inhabit most of the warmer portions of the globe. Thus the Rattlesnakes are well worthy of detailed consideration.
Aside from their deadliness, the Rattlesnakes possess a strange fascination that attracts scientist and novice alike. Their rich, velvety colours, sinister form and sullen demeanour, combined with the ominous, warning sound of the rattle, are phases of character that produce a lasting impression upon the observer. The writer has studied living examples of many species of deadly snakes--the South American bushmaster and the fer-de-lance, the African puff adder and the berg adder, and such East Indian species as the king cobra, the spectacled cobra and Russell's viper, and although there is indelibly stamped upon his mind the bloated body, the glassy stare and the rhythmic hissing of the berg adder, the rearing, uncanny pose of an infuriated cobra, there is one image vivid above all--the Rattlesnake. Thrown into a gracefully symmetrical coil, the body inflated, the neck arched in an oblique bow in support of the heart-shaped head, the slowly waving tongue with spread and tremulous tips, and above all, the incessant, monotonous whir of the rattle. One stroke--a flasher that fiat head would inject a virus bringing speedy death. Yet the attitude of the snake is to be admired. It denotes a creature attacked by a powerful enemy and bravely defending its life. The snake never advances, nor makes actually hostile movements. If the enemy retreats but a few steps the reptile endeavours to glide for cover, but at close quarters the attitude spells one word--Beware! As the argument is backed by a pair of deadly fangs, this serpent must be considered, so it seems, as man's very dangerous enemy, and the destruction has long since begun. Of the tens of thousands of these reptiles slaughtered, there may be said to be barely one accident to man in the killing of ten thousand Rattlesnakes. To illustrate this, it might be explained that a death from the bite of a Rattlesnake in the United States is so rare a thing the occurrence appears as a first page paragraph in nearly every newspaper of the Union.
The scarcity of accidents from these reptiles, which inhabit all portions of the United States, may be accounted for by the fact that Rattlesnakes inhabit ground not generally serviceable to man. Moreover, when these snakes are approached, the rattle usually gives ample warning of their presence. On several occasions, as the writer has been hunting for Rattlesnakes, he has heard the rattle from among tumbled masses of rocks the snake thus disclosing its presence when it might easily have remained concealed.
Although those species of Rattlesnakes that inhabit the open prairies and fertile farming country of the Central and Western States have decreased in number almost to the point of extinction, in many large areas under cultivation, other species that have for a time suffered to a similar extent have of late years become abundant, owing to conditions offering almost complete protection. Large mountain areas in our Eastern States have been bought up as private game preserves. The owners of such estates have a natural desire to preserve their forests and exclude trespassers from their lands, that the deer and pheasants may thrive. The cutting of timber ceases; the old wood trails disappear in a tangle of undergrowth--and the wandering of numerous pothunters, who kill every creature that crosses their path, stops altogether in these domains. Some of the most charming country in the East has thus been effectually preserved. It is quite refreshing to the nature-lover to visit one of these great tracts and observe the undisturbed stretches of fine forests in regions that are being devasted by the sawmill. In these great, fenced in areas, conditions have returned, from the standing of the Rattlesnakes, to what they were when this country was in its infancy.
Several species of Rattlesnakes inhabit Mexico and Central America that are not found in the United States. One large and very handsomely coloured species is confined to South America. With the exception of one Mexican species extending southward into that continent, this is the only South American Rattlesnake.
The Rattle.--Compared with all other genera of serpents, the rattle is a unique appendage. The closest approach to it is the well-developed spine existing on the tail of many snakes. The natural use of the rattle remains unknown. To presume that the snake is provided with this appendage to warn enemies away from its formidable fangs, is to fall in line of very bold theory. Nature has no apologies to make for the distribution and existence of her creatures whether innocent or dangerous, and She is not lavish in placing danger signals to guard the unwary. The argument has been advanced that the rattle is used as a call, during the breeding season, which is not illogical, as snakes are not wholly deaf, although lacking external ears. They appear to appreciate the vibrations of certain sounds--possibly with the aid of the delicate tips of the tongue or by means of a sensitive development of the scales. From the examinations of freshly captured snakes, it appears that the rattle is used but little in a state of nature, for it rapidly shows traces of wear and breakage in the frequent use of it by caged specimens, though it may have been quite perfect at the time of their capture. Many snakes, both venomous and innocuous, vibrate the tail when greatly angered. The Rattlesnake does likewise, hence the "warning" sound. There are good arguments pointing to the occasional use of the rattle to decoy prey within the reach of the fangs--but it is the writer's purpose to explain what is actually known about the rattle and not to enter into theory.
A persistent and popular idea is to the effect that the age of a snake may be told by counting the rings or segments of the rattle. With the majority of specimens, such calculation is impossible.
In the early part of June, it prepares to shed its skin again and the distension at the base of the diminutive rattle shows the presence of another "ring" to be uncovered. This ring proves to be considerably larger than the first one; its increased size appeals to the growth of the snake itself. The rattle now appears like Fig. 3 of the series of illustrations. In this way the development of the rattle goes on, each ring being of. larger size than the preceding until the snake has attained maturity and growth ceases.
It can thus be appreciated that if the rattle of a snake possesses the original bullon of birth, we may estimate the age of the reptile by allowing the button and first ring for about the first nine months--this including the period of the first hibernation, and counting each three additional rings as a year. The reptile usually sheds its skin three times during the warm season, in the spring, during mid-summer and in the fall. If the button has been lost through wear or accident and the rattle has a distinctly tapering outline toward its tip, the number of lost segments may be estimated, but if all the segments are of uniform size, it will be understood that the rings of youth have been lost and possibly many others. With such a specimen there is no way of ascertaining the age except to realise that it is fully grown and mature at the time the terminal ring of the rattle was developed as this agrees in size with that at the base of the appendage.
Sometimes we find snakes with the segments of the rattle decreasing in size toward the base. A specimen captured by the writer in Pennsylvania had a rattle like this. The character was accounted for by stories of nearby residents of an extensive forest fire that swept through the region several years back. At the time of the fire, the snake was probably sheltered in some deep crevice of a ledge and escaped the conflagration, which consumed the fallen ,and hollow tree trunks in which were the nests of the wild mice and ground squirrels. In consequence, living had been scanty for some time.
Captive snakes that fast for lengthy periods, or feed irregularly, grow rattles like this, but upon regaining their appetites, the succeeding rings are of normal size.
The longest rattle examined by the writer consisted of seventeen segments, which was unusual, owing to the average limited number, as previously explained. On this rattle, the last three rings were worn and broken, and they were shaken from it several weeks later when the snake--a black Timber Rattlesnake--wag so disturbed that it became greatly enraged and rattled steadily for about an hour. The writer was once asked to examine what was considered a unique possession--in one of our large scientific institutions. This was a rattle consisting of twenty-four rings. Close inspection showed the wonderful organ to be composed of the rattles of three snakes of similar size, snapped into one another. This is easily done. On many occasions in the reptile house of the New York Zoological Park it has been found appropriate to adorn fine rattlers that have lost their chief ornament in the excitement of capture, with a rattle from the souvenir box of such curiosities. (A figure shows the internal composition of the rattle).
The Rattlesnakes are divided into two genera--Sistrurus, the Pigmy Rattlesnakes, and Crotalus--containing the majority of the species. The species of Sistrurus are small, rarely attaining a thickness of a man's forefinger and a length of a yard. Crotalus contains species both large and small. A small Rattlesnake is one that attains a length of not more than three feet. The large species reach a length of six to eight feet.
The Pigmy Rattlesnakes may at once be distinguished from other rattlers, by the scalarion of the top of the head. The head is covered with large, symmetrical shields, arranged like those of the harmless or colubrine snakes. But from the latter the Sistruri may be told at a glance by the rattle and the characteristic pit of the family Crotalidae.
