As the weather heats up, rattlesnakes especially become more active. They, like humans, tend to explore when the weather gets warm. Also like humans (those who enjoy the great outdoors, that is), rattlesnakes tend to avoid developed areas, preferring undisturbed, natural habitats. That means the more you hike, hunt, camp, fish, bike and recreate in wilderness areas, the greater your chances of encountering a pit viper. And another thing they have in common with humans is they tend to be found in log piles and rocks and other natural "seats" where you might be likely to enjoy your lunch or bask in the sun. They also can be found in swampy areas. Snakes are able to regulate their body temperature by moving in and out of shade. A warmer body allows a snake to move faster when trying to catch prey (insects, slugs, frogs, birds, bird eggs, small mammals, and other reptiles). 
Rattlesnakes are native to North America, living in diverse habitats. There are 36 known species of rattlesnakes, with between 65 and 70 subspecies. The state with the most types of rattlesnakes are Texas and Arizona. Even baby rattlesnakes possess dangerous venom as soon as they hatch. Rattlesnakes all have the ability to rattle, hence their name, but they don't always make a rattling sound, so someone can be standing next to one and not even know it.
It is impossible to know what each and every variety of poisonous rattler looks like, but in general, they all have a triangular head, much wider than the neck, thick body with dull skin, and bands of color or splotches of color on backs and tail. Become familiar with the most common snakes found where you live or recreate. The three most common are:
Northern Pacific Rattlesnake: The color pattern is usually dark-brown, dark-gray, olive-brown, or sometimes black or pale yellowish ground color overlaid dorsally with a series of large, dark blotches with uneven white edges. These blotches are also wider than the spaces that separate them. Additionally, a lateral series of blotches, usually darker than the dorsal blotches, is clearly visible on all but the darkest specimens. The first rings of the tail are about the same color as the last body blotches, but these rings become progressively darker; the last two rings, at the base of the tail, are usually black. The belly is pale yellow, usually with brown spots. A large, dark-brown blotch on the snout has a pale border behind it. There is a dark brown postocular stripe with a white border that extends from the eye to around the angle of the jaw.
Western Diamond-Backed Rattlesnake: A large and heavy-bodied species, this rattlesnake's coloring varies from chalky gray to dull red, appearing dusty due to minute flecks and dots on the scales. As suggested by its common name, this species has diamond-shaped markings over most of its body, which are edged with black and white. These markings are replaced by conspicuous black and white bands towards the rear of the tail, just in front of the rattle, while the head has two characteristic pale stripes, one in front of the eye and the other behind, which run diagonally down the head towards the mouth.
Timber Rattlesnake: This is the only rattlesnake species in most of the populous northeastern United States; it is the third largest venomous snake in the United States.The physical color of a timber rattlesnake can vary widely depending on its area. Some are gray with a rich black pattern, some are tan with a sulfur yellow pattern, and some are a combination of both. They have V or W-shaped crossbar markings, which create a distinct pattern across its back. Generally they have a wide head and narrow necks. They have a distinctive rattler on its tail made up of a special scales. Their eyes are yellow, with elliptical pupils. These are large snakes, generally ranging from 36-60 inches (90-152 cm) in length and between 1.5 to 3 pounds.
It is estimated that 7,000 to 8,000 people are bitten by venomous snakes in the United States each year, resulting in many deaths. The most important factor in survival is the time elapsed between the bite and treatment. Most deaths occur between six and 48 hours after the bite. If antivenom treatment is given within two hours of the bite, the probability of recovery is greater than 99 percent. Still, any bite by a rattlesnake must be considered a life-threatening medical emergency!
When a bite occurs, the amount of venom injected is under voluntary control by the snake. The amount released depends on a variety of factors, including the condition of the snake (e.g. having long, healthy fangs and a full venom sack) and its temperament (an angry, hungry snake that has just been stepped on vs. a satiated snake that was merely surprised by walking near it). About 20% of bites result in no envenomation at all. Common symptoms include swelling, severe pain, tingling, weakness, anxiety, nausea and vomiting, hemorrhaging, perspiration, and eventually heart failure. Local pain is often intense, and will increase. Children generally experience more severe symptoms because they receive a larger amount of venom per unit of body mass.
What to do if bitten by a snake:
If bitten by a rattlesnake, stay calm and send someone to call 911. Always hike with a friend so you can help each other in case of emergency. The victim should remain calm by lying down with the affected limb lower than the heart. Do not waste precious time on tourniquets, "cutting and sucking," or snake bite kits. If you are by yourself, walk calmly to the nearest source of help: another person or a phone to Dial 911. Do Not Run. If you are not sure what kind of snake bit you, check the bite for two puncture marks (in rare cases one puncture mark) associated with intense, burning pain. This is typical of a rattle snake bite.
Although snakes of any kind are not "out to get you," bites can and do occur. Your best defense is don't take a chance! Wear snake gaiters or snake boots when in known snake country - whether that be the desert or woods - and greatly reduce your chances of being bitten!
