I. DESCRIPTION:
Pit viper.
Characterized by a tail rattle that produces a buzzing sound when vibrated.
Rattle is composed of horny, loosely connected segments added one at a time with each skin shedding, usually containing six to ten segments.
Triangular-shaped head that is broader than the neck.
Coloring varies by species, but usually blends in well with its surroundings, i.e., mottled or banded in shades of tan and brown, and also combinations of grayish green, orange, red, bright green, yellow, black or peach.
II. GEOGRAPHICAL RANGE AND HABITAT:
- Ranges from Canada to South America though concentrated in the southwestern United States.
- Arid regions.
III. DIET:
- Lizards, ground squirrels, small rabbits, rats and mice.
- Young feed mainly on lizards.
IV. LIFE CYCLE/SOCIAL STRUCTURE:
- Congregate in rockslides or crevices in winter to hibernate.
- When temperatures begin to warm in May and early June, hibernation ends; remains near den entrance for a few days sunning, then makes its way to summer location; rarely travels more than a mile from its den; seen most often in the spring and fall migrations to and from its winter home.
- Hunts at night and, during digestive period, remains inactive and out of sight for days at a time.
- Eggs are retained in mother's body until hatched; young are born alive, typically around the end of July.
- Young completely independent of the mother; born with a small rounded tip on the tail known as a pre-button; capable of biting and envenoming from birth; remain in the area of birth for the first 7-10 days until baby skin is shed and first rattle added, losing pre-button; begin to disperse and search for food; must have at least two rattle segments to produce sound.
- Many young don't survive the first year, either dying of hunger or being eaten by prey (birds and animals); if the summer is survived, may perish during the winter if can't find suitable warm crevices in which to hibernate.
- Young grow rapidly; every time hibernation is completed, skin is shed and with each shedding (molting) a new rattle appears; during rapid growth of the first few years, may molt three times annually.
V. SPECIAL NOTES/ADAPTATIONS:
- Small heat-sensing pit between each eye and nostril that aids in hunting.
- Nocturnal and has no control system for its body; can't tolerate extreme heat or cold, thus remains underground during the day hidden in burrows, under rocks, or in the shade of shrubs.
- Venomous.
- When feeding, strikes rather than attempting to hold prey; can strike 1/4-1/2 of its body length; hollow fangs penetrate victim's flesh and venom is injected as though through twin hypodermic needles; small prey is immediately stunned and larger animal runs some distance before it dies (it is followed and swallowed whole).
- Rattle serves as a warning signal when threatened; does not rattle when hunting and sometimes when surprised; vibration of the muscular tail causes separate segments to bounce against adjoining ones, creating buzzing sound.
VI. ENVIRONMENTAL IMPACT:
- Controls rodent population, thus minimizing rodent-born diseases.
VII. MORE RATTLESNAKE FACTS:
- Throughout the world there are many snakes whose venom can be fatal to humans. However, in the United States, there are only four: coral snake, copperhead, cottonmouth water moccasin, and rattlesnake. Designating a snake as dangerous involves many classifications, such as possessing large quantities of highly toxic venom, long fangs capable of inflicting deep wounds, and color and pattern that camouflages its presence.
- Rattlesnakes have relatively weak venom when compared to the world's other vipers and cobras.
- The number of rattles is not a true indicator of age because as many as three rattles may appear in a year, and rattles wear out or break off.
- When disturbed, a rattlesnake will try and withdraw on most occasions. However, if it feels cornered, the startling, sizzling buzz of its rattle is an unmistakable warning.
- A rattlesnake bite is a defensive reaction and should not be considered an act of aggression.
- In the United States, humans experience about 8,000 bites from venomous snakes each year. Of those, an average of 12 per year (less than 1 percent) result in death. More people die each year from bee stings or lighting strikes.
- One-third of all rattlesnake bites are "dry bites," meaning no venom is injected.
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