A creature is poisonous if its toxins are harmful when ingested or absorbed through contact (e.g., a poison dart frog). An animal is venomous if it actively injects toxins, typically through a bite or sting, using specialized structures like fangs. All dangerous North American snakes are venomous, not poisonous. While most snakes referred to as “black snakes” are harmless, some venomous species can also appear entirely black, making identification crucial.
The Truth About Common Black Snakes
The two most common species known as “black snakes” across North America are entirely non-venomous. These beneficial reptiles are the Black Racer (Coluber constrictor) and the Black Rat Snake (Pantherophis obsoletus). Both species control rodent populations and are generally defensive, only biting if threatened or handled.
The Black Racer is a slender snake with smooth, matte scales and a uniform black coloration, often featuring a white chin and throat. True to its name, this snake is exceptionally fast and typically flees quickly when approached. The Black Rat Snake, or Eastern Rat Snake, is a longer, heavier-bodied constrictor with slightly keeled, or ridged, scales that give it a duller texture. This species is also an expert climber, frequently found in trees or barns, and often displays a faintly patterned or checkered underside.
Identifying Venomous Snakes That Appear Black
While the majority of black snakes are harmless, some venomous pit vipers can have a dark color phase that makes them appear solid black. The most common of these is the Cottonmouth (Agkistrodon piscivorus), and in certain regions, the Timber Rattlesnake (Crotalus horridus) can also be quite dark. Differentiating these heavy-bodied pit vipers from the slender, non-venomous black snakes relies on examining three key morphological features.
Venomous pit vipers possess a distinctly triangular head that is notably wider than their neck. In contrast, non-venomous black snakes have a more streamlined head shape that is proportionate to the width of their body. The eyes of a pit viper feature elliptical, vertical pupils, similar to a cat’s eye, whereas all non-venomous North American snakes have round pupils.
The most specific identifier is the loreal pit, a deep, heat-sensing organ located on each side of the venomous snake’s head, positioned between the eye and the nostril. Furthermore, venomous snakes tend to have a thicker, heavier body relative to their length. They also have a single row of scales on the underside of their tail, while non-venomous snakes have a double row of subcaudal scales.
Safe Encounter Guidelines
Encountering any snake requires maintaining a respectful distance to ensure safety for both the person and the reptile. The most important rule is to remain calm and slowly back away, keeping a distance of at least six feet from the snake. Snakes are generally non-aggressive and will only bite if they feel cornered or directly threatened.
Never attempt to touch, capture, or kill a snake, even if you believe it is non-venomous, as this is the primary cause of defensive bites. When outdoors in areas with tall grass, leaf litter, or rocks, be sure to watch where you step and avoid placing hands into concealed areas. If a snake is found near a home, the safest course of action is to wait for it to move on or contact a professional wildlife removal service for relocation.