The Broad-Banded Copperhead snake gets to be 2 to 3 feet long.   

The Broad-Banded Copperhead is not common to Austin but can be found in other areas like Elgin and Bastrop.

These snakes have broad bands in alternating colors of copper and light tan. The juveniles have greenish-yellow tips to their tails, which fade as they get older. These snakes feed on rodents, birds, and amphibians. Preventative measures are the same for the Copperhead as for the Diamondback Rattlesnake. 

The Texas Coral Snake is a slender snake averaging 2 feet in length. 

This snake has red, yellow, and black bands encircling the body, with the red touching the yellow. Although venomous, these snakes have a hard time injecting venom into a human because of their small head and their short, fixed fangs. Bites usually occur only on the hand on or between the fingers, and the snake has to chew in order to inject the venom, and most people do not let them hang on for long enough to do serious damage! They are usually encountered by people gardening or weeding. Wearing thick gloves is the safest way to avoid problems with the coral snake while gardening.

These snakes feed mainly upon other snakes and sometimes lizards, so they are attracted to yards landscaped with timbers or flagstones since that tends to attract the other smaller snakes on which they can feed. In other parts of Texas, there are found several other snakes which mimic the coral snake's colors, but these snakes are not common to this area. In Austin, if it looks like a coral snake, it probably is one, as they are somewhat common to this area. On the other hand, I have found escaped pet Milksnakes in Austin. There are NO recorded deaths related to Coral snake bites in the state of Texas.

Timber Rattlesnakes average 3 to 4 feet in length.

The Timber Rattlesnake, also referred to as the Canebrake Rattlesnake, is generally found in the Central and Eastern piney woods area of Texas. This is a threatened species protected in Texas. A few have been found in Bastrop County but are extremely rare. The snake's background color is usually a shade of gray, tan, or brown. On the snake's back are dark chevrons or V-shaped bands. An orange stripe of varying shades and width runs from head to tail sometimes fading in the last third portion of the snake. The tail is black or dark brown. They are a mild-mannered snake with potent venom.

The Western Cottonmouth is a heavy-bodied snake averaging 2 to 3 feet in length. 

Adult coloration can be almost all black, with a little bit of brown, or they can appear as black and brown-banded. The juvenile pattern is much more pronounced with the tip of the tail a greenish-yellow. This snake isn't common in the Austin area. I've never seen one here in Travis County, but I get a lot of calls from people who think that they have seen one, and it has always been a water snake. They have never been recorded in Williamson County.

The Cottonmouth likes slow-moving water or quiet ponds without a lot of human activity, they feed on frogs, fish, rodents, and birds. They like to sit very still and blend into their surroundings. If bothered, they will first try to get away, but if cornered they will be open their mouth and gape, showing their characteristic white mouth. Most snakes have a white mouth, so this is not a way to identify this snake. When sitting in the water, they float on the top of the water. They hold their head elevated, with their body and tail also on top of the water.

Juveniles have a distinctive banding pattern and, like copperheads, a bright green tail tip. As they get older, they tend to darken up, losing much of this banding pattern and becoming almost solid-colored, and losing the green color on the tail.

Western Diamondback Rattlesnake adults average 3 to 4 feet.

A gray and brown snake with the diamonds being a darker brown. The tail has broad black and white rings just before the rattle. It is rare for the rattle to be completely broken off. These snakes prefer to avoid places with human activity, but if food or water is scarce, they will forage for food anywhere. They primarily eat rodents and birds found on the ground. The Diamondback is usually not a tree or house climber but is able to cope with a stack of logs or piled rocks.

The best way to prevent these snakes from coming around is by not having places for rodents to live. Logs and lumber should be kept well off the ground and rocks should be stored spread out rather than piled up. Remove all debris from the yard such as stacks of plywood, roofing tin, old fallen buildings, etc., and keep the yard mowed as far from the house as possible. If the yard is 'privacy' or 'chain link' fenced, a barrier such as hardware cloth or fine mesh screen can be installed to physically bar a snake from crawling under or through the fence.