The Cottonmouth, also known as the “Water Moccasin”, are very heavy bodied, semi-aquatic snakes who are in the pit-viper family. This snake is the largest of the genus Agkistrodon. These snakes regularly reach 31″ and there are a few specimen who have reached 71″, although be it rare. These snakes can regularly be identified by dark crossbands on an olive to dark brown background. The Eastern Cottonmouth, Agkistrodon p. piscivorous, is one of three sub-species and generally keeps the banding throughout life although it does typically fade with age. The Florida Cottonmouth or Agkistrodon p. conanti and the Western Cottonmouth or Agkistrodon p. leucostoma, generally darken with age to the point the banding may become difficult to observe. The only other Agkistrodon living in the USA is Agkistrodon, contortrix, the Copperhead.
Juveniles, look much like the adults except for the coloring being much more vivid. Young, like all Agkistrodon and some other pit-vipers, have a yellow tail which is used to lure pray into strike range.
*Note in the picture, the vivid markings on this juvenile A. p. piscivorous. Also note the “heat-pit” located just in front of the eye. The eye is also “cat like”.
The Cottonmouth feeds on a variety of prey to include rodents, frogs, fish, and other reptiles to include other snakes. Prey is typically ambushed near the edge of the water. I have personally found the Eastern Cottonmouth eating large frogs that have been killed on the road.
The Cottonmouth loves to bask in the sun on the edge of the water. When spooked, they will lunge into the water. Agkistrodon typically swim on top of the water with the head sticking up above the surface. This is a helpful bit of knowledge, as harmless water snakes, Nerodia, a non-venomous genus of snakes, typically swim under the water.
The Cottonmouth, although considered semi-aquatic, is known to travel overland in search for amphibians at night. These guys love to get in roads that travel near water on rainy nights, making them an easy to cruise on rainy nights.
The Cottonmouth, like other semi-aquatic snakes, are known for their nasty attitudes. In my personal experience (which I would consider frequent and knowledgeable with this species), I feel this is highly unjustified in this species. Cottonmouth are frequently reported to lunge towards a would-be predator and even chase people. Based on my observations of snake species, I believe this to be a combination of wrong identification and exaggerated stories. Nerodia, like the Red Belly Watersnake, are an unrelated family of harmless water snakes. They are known to lunge quickly towards a predator before making a quick escape. Cottonmouth and Water Snakes are commonly confused with each other. In my years of dealing with Cottonmouth, I have found only a few I would call aggressive, and NONE have ever chased me! The vast majority of the hundred or so specimen I have observed were very calm and didn’t strike until prodded for some time during examinations.
Cottonmouth, although generally docile snakes, do posses a very strong venom and all bites should seek medical attention immediately. There are many documented cases of severe bite and there are reports of death from A. piscivorous bite.
Although this species can be found very far from water, it is typically found near aquatic environments. They prefer the still water of swamps, canals, and very slow moving creeks and rivers. This species, in some populations, is regularly found in drainage ditches.
Cottonmouth, like all pit-vipers, give live birth. Adults mate in spring and give birth in the early fall to 2 to as many as 15 young.
Cottonmouth get their name from the white coloration on the inside of the mouth. They typically display the inside of the mouth when aggravated. I believe this does play a part in the misconception of this species being aggressive.
1. Spring and Fall look for them basking on the edge of water sources on nice warm days. They love to soak up the rays.
2. In the heat of summer, look for them on the water’s edge lying near stumps, fallen logs, or along the marsh-line.
3. This species, like other semi-aquatic snakes, are very curious of objects floating in the water. I have seen many swim right up to floating logs or even boats. The act of swimming up to boats for closer inspection also add to the story of the “chasing cottonmouth”.
4. This species can easily be cruised in populated areas at night, especially on humid rainy nights. For best results cruise during the rain during normal showers or during the approach of a warm front. Cold front storms typically produce much less results.
For More Information on Agkistrodon piscivorous and other North American Herps, check out: