There are almost 30 species of snakes in the state of Iowa. These help control populations of rodents and other small mammals. Whether it is the 12 inch long brown snakes or the 6 foot long black rat snake, they serve a purpose in the ecosystem – eating worms, slugs, insects, mice, ground squirrels, rabbits and more. Only 4 of those 30 species are venomous.
The timber rattlesnake (Crotalus horridus) is the only venomous snake documented in Wapello County, but it is not often encountered. The timber rattlesnake grows to around 4 feet in length. Color varies from brown or tan to gold or gray. They have black bands down the length of their body. Venomous snakes in Iowa have a triangular or spade-shaped head, while non-venomous snakes have a more rounded and smaller head. Don’t let the hognose snake fool you though. It can flatten its head to make it look bigger, but it is not venomous.
Venomous snakes also have elliptical or vertical pupils (like a cat). We don’t recommend getting that close to determine the type of snake in front of you. Of course a rattlesnake also has a rattle at the end of the tail that they will hold up and rattle as a warning. However, some non-venomous snakes will rattle their tail in dry leaves and grass to try to trick you – and other possible predators – into believing they are venomous.
Timber rattlesnakes are protected in 14 of Iowa’s 99 counties – excluding within 50 yards of an actively occupied residence. All other Iowa snakes are protected in all 99 counties. They, however, are often not aggressive and will try to avoid humans if possible. If we leave the snake alone, we should not fear a bite. In the event of a bite, they are often dry bites or bites that don’t inject venom. A rattlesnake (or any other snake really) is not going to seek you out just to attack you. If it rattles at you, it is best to step away. If it bites, seek medical help.
Timber rattlesnakes often seek out rocky slopes for their winter hibernation/den sites. Development and construction across the state often threatens their habitat. Pesticides and herbicides used to get rid of pest animals and plants leads to a lower number of prey available to these snakes. They are also poached for the exotic pet trade. Fire suppression in some areas has allowed cedar and other shrubs to encroach on some prairie areas. This discourages their prey and therefore the snakes from using these areas.
These snakes are pit vipers due to the pits on the sides of their heads. These pits are sensitive to heat and help them find warm-blooded prey in the dark. This is useful since timber rattlesnakes have poor eyesight. Of course have a tongue that collects scent particles helps as well as being able to detect vibrations through the ground.
We receive many calls about rattlesnakes, and the often turn out to be a non-threatening snake such as brown water snake, bull snake, fox snake or one of many others found around here. Any snake you encounter should be left alone, but you should take some time to observe them from a distance. You never know what you might see and learn.