Most venomous species in North America are pit vipers- Cottonmouths, Copperheads, Rattlesnakes, etc. Pit Vipers have triangular heads. They also have pits- little holes on the sides of their heads for additional heat sensory. All pit vipers have elliptical pupils- “cat” eyes. Colors are very bad for identifying venomous snakes in North America- in most cases they are no brighter than normal snakes. Some rattlers can be identified by scale patterns, but it is doubtful you will be up to counting scales when confronted with a snake.
Rattlesnakes will “rattle” their tails- but many species imitate this by beating their rattle-less tail on the ground to scare you away, so this is a fairly ineffective method of identifying a snake. The Cottonmouth displays a unique open mouth of white skin. Coral Snake and King Snake color patterns can be differentiated by the rhyme “Red touches black, friend of jack. Red touch yellow, you’re a dead fellow.” A quicker way to remember it is to think of a stoplight- the light turns yellow before it turns red. Yellow and red touching means caution, means Coral Snake.
Several nonvenomous snakes have cat eyes, pits, or rough scales. What makes the snake is the combination of these characteristics. By familiarizing yourself with images of venomous snakes, you should be able to identify them apart from nonvenomous snakes with a fair sense of competency. Can you guess which snake in the image is the venomous water snake?