Snakes in Uruguay

Uruguay has 50+ snake species recorded in our database, 12 of them venomous. The great majority of species are non-venomous, so most snakes a person encounters in the country pose no medical threat at all. Uruguay is a small, low-lying country, and its snake fauna reflects the temperate grassland and subtropical influences that meet here rather than the explosive diversity of the tropics farther north.

The geography that shapes this fauna is dominated by rolling grasslands, the pampas, which cover most of the interior. These open landscapes are broken by gallery forests along rivers, palm savannas, rocky outcrops, coastal dunes and wetlands, and the marshy lowlands near the Atlantic and the Rio de la Plata. Each of these habitats supports a different mix of snakes. Grassland species hunt rodents and frogs across the open country, riverine and wetland species favor the damp margins of waterways, and the warmer northern districts share species with neighboring Brazil and Argentina. This range of habitats, more than sheer size, is what drives the diversity recorded here.

The medically important venomous snakes of Uruguay fall into two groups. The first is the pit vipers, represented by lanceheads of the genus Bothrops, including the species commonly called yarara, and by the South American rattlesnake, Bothrops and Crotalus being the two pit viper lineages present. These are responsible for the overwhelming majority of serious snakebites in the country. The second group is the coral snakes of the genus Micrurus, brightly banded elapids whose venom acts on the nervous system. True cobras, mambas, and sea snakes do not occur in Uruguay, so the practical concern is limited to the pit vipers and coral snakes. The lanceheads are the snakes most often involved in dangerous bites because they are relatively common and well camouflaged in grassland and brush.

The non-venomous majority is large and varied. It includes many colubrid snakes such as the racers and false water snakes, water snakes, and a range of small, secretive, and burrowing species that make up the bulk of the 45 non-venomous species recorded. Some harmless species are boldly patterned and are sometimes mistaken for coral snakes, while others are mild-mannered residents of gardens and farmland that go entirely unnoticed. These snakes are a normal part of the Uruguayan countryside and are far more often seen than the venomous few.

Snakes earn their place in these ecosystems. By preying on rats, mice, and other rodents, they hold down populations that would otherwise damage crops, contaminate stored grain, and spread disease around farms and homes. Other snakes control frogs, lizards, insects, and even other snakes, keeping the food web in balance. A landscape with a healthy snake population is usually one with fewer rodent problems, which is a direct, practical benefit to the people who live and farm there.

On safety, the honest picture is reassuring. Most snakes in Uruguay are harmless, and the main medical threat comes from the lanceheads and, less often, the coral snakes and the rattlesnake. A venomous bite is a medical emergency that is treated with antivenom and supportive hospital care, so the right response is to get the person to a hospital quickly and contact emergency services. No wild venomous snake should ever be handled, and even snakes that appear harmless should be left alone and given room to move away. If a bite occurs, do not attempt home remedies; seek professional medical care immediately. In the United States, Poison Control can be reached at 1-800-222-1222; elsewhere, contact local emergency services.