The Florida Keys host a population of both native and non-native snake species. While the unique ecosystem of the Keys, characterized by small, separated islands and high development, supports a lower diversity of snakes than the Florida mainland, several species are well-established. This area is home to unique subspecies that have adapted to the isolated environment, alongside a few species that cause safety concerns for residents and visitors. Understanding which snakes are present, where they live, and their ecological roles is helpful for anyone spending time in this subtropical environment.
The Common Native Species
The majority of snakes encountered in the Florida Keys are non-venomous and pose no threat to people, serving a beneficial role in the local ecosystem by controlling rodent and lizard populations. Perhaps the most notable of these is the Lower Keys population of the Red Rat Snake, often known as the Corn Snake (Pantherophis guttatus). This constrictor is highly adaptable, inhabiting pine rocklands, rockland hammocks, and disturbed urban areas where it often preys on small mammals and non-native lizard species. The Lower Keys Red Rat Snake population is recognized for its unique status and is listed as a species of special concern due to habitat loss and fragmentation.
Another frequently seen native is the North American Racer (Coluber constrictor), commonly called the Black Racer, which is known for its speed and sleek, black body. This agile snake is active during the day and can be found across the Keys, using its rapid movement to hunt small prey in a variety of habitats. The small, secretive Ringneck Snake (Diadophis punctatus) is also present, identifiable by its dark body and bright orange or yellow neck ring. A distinct subspecies of the Ringneck Snake, Diadophis punctatus acricus, is endemic to the Lower Keys and is listed as a threatened species within Florida.
Venomous Snakes and Risk Assessment
While the Keys are often perceived as being free of dangerous reptiles, two venomous species are confirmed to be present, requiring awareness from people in the area. The most distinct venomous snake is the Eastern Coral Snake (Micrurus fulvius), which is an elapid, a family that includes cobras and mambas. This snake possesses a potent neurotoxic venom that affects the nervous system, but bites are exceedingly rare due to its shy, secretive, and burrowing nature. It is identifiable by its slender body and alternating red, black, and yellow bands, with the pattern of red and yellow bands touching each other being a distinguishing feature from non-venomous mimics.
The Eastern Coral Snake occurs throughout Florida, including the Upper Florida Keys, and is most often found in sandy soil, under debris, or in woodland habitats. Another pit viper, the Florida Cottonmouth (Agkistrodon conanti), is also found in the Upper Keys and ranges as far south as Key Vaca. Cottonmouths are not strictly absent from the Keys, though they are generally not as abundant as on the mainland. Other mainland pit vipers, such as the Eastern Diamondback Rattlesnake, are not established in the Keys.
To avoid encounters with venomous snakes, a simple precaution is to avoid placing hands or feet into areas where a snake might be hidden, such as under logs, rocks, or dense vegetation. If a snake is encountered, the best practice is to slowly back away and allow the animal to move on without interference. The Eastern Coral Snake, in particular, has fixed, short fangs and must often hold on or chew to inject its venom effectively, unlike the strike-and-release behavior of pit vipers.
Managing the Invasive Threat
A significant ecological challenge in the Keys comes from non-native species, with the Burmese Python (Python bivittatus) representing the largest threat. These extremely large constrictors, native to Southeast Asia, have established a population in South Florida due to escaped or released pets, and their range extends into the Keys, particularly Key Largo. While the problem is more widespread in the vastness of the Everglades National Park, pythons have been confirmed to be breeding on Key Largo, which is a major concern for the small, isolated island ecosystem.
The pythons are generalist predators, and their presence directly threatens the small, endemic mammal populations unique to the Keys, such as the endangered Key Largo woodrat and the Key Largo cotton mouse. Researchers have documented the consumption of these sensitive native rodents by pythons, illustrating the severe impact this invasive species has on the islands’ biodiversity. Management efforts include prohibiting the species as pets and encouraging the humane removal of pythons whenever they are encountered. The natural barrier of saltwater between the islands may slow the spread of these semi-aquatic snakes, but it has not been a complete deterrent to their establishment.