Modern sloths are known for their slow, arboreal lifestyle and are exclusively found in the tropical regions of Central and South America. They are divided into two main families: the two-toed and three-toed sloths. Currently, no wild populations exist within the continental United States or Canada, as their natural range only extends north into Central America. However, the continent was once home to a much different, and significantly larger, variety of these animals.
Current Habitat and Range
The six living species of sloth are confined to the lowland tropical forests of Central and South America, requiring a consistently warm and humid climate to survive. Their habitat spans from eastern Honduras down through the Amazon basin into countries like Brazil, Colombia, and Peru. Sloths spend almost their entire lives in the rainforest canopy, where they sleep, eat, and move among the branches.
This range includes the tropical forests of Central America. For example, the brown-throated sloth is the most common species, extending from Honduras through Costa Rica and Panama. The Hoffmann’s two-toed sloth is also found in countries like Nicaragua.
They rely on a continuous canopy for food—primarily leaves—and protection from predators. Their low-energy lifestyle is adapted to the specific conditions of a tropical rainforest, where food is abundant and temperatures are stable. The restricted range of the pygmy three-toed sloth, limited to a single island off Panama, highlights their specialized habitat requirements.
The Extinct Ground Sloths
The question of sloths in North America becomes relevant when looking at the fossil record, which reveals that the continent was previously home to numerous species of giant ground sloths. These were massive creatures that roamed the land during the Pleistocene epoch, up until about 11,000 to 12,000 years ago.
The largest extinct sloths, such as Megatherium, were comparable in size to modern elephants, standing seven meters tall and weighing up to 8,000 pounds. Another genus, Megalonyx (meaning “great claw”), was named by Thomas Jefferson and was widely distributed across the United States, with fossils found as far north as the Yukon and Alaska.
These ground sloths adapted to a wide variety of habitats, including savannahs, deserts, and even the boreal forests of Canada, unlike their modern counterparts. Their size provided insulation and protection from predators, allowing them to thrive across the continent for millions of years.
Their extinction coincided with the end-Pleistocene event, a mass disappearance of megafauna across the Americas. The disappearance of these large mammals is thought to be linked to rapid climate change following the last Ice Age, human hunting, or a combination of both factors.
Limiting Factors for Sloth Survival
The physical and metabolic limitations of modern sloths prevent them from surviving in the temperate climates of the northern United States and Canada. Sloths have a low metabolic rate compared to other mammals, restricting their ability to generate internal body heat. This low metabolism is an energy-saving adaptation to their low-calorie diet of leaves.
They cannot regulate their core body temperature effectively, making them highly dependent on stable, warm tropical temperatures. When ambient temperatures drop below their comfortable “thermally-active zone” (around 26 to 30 degrees Celsius), their metabolic rate drops further. This diminished function makes them vulnerable to cold stress.
Their slow rate of digestion, which can be up to 24 times slower than similar-sized herbivores, is a major constraint. A lack of consistently available tropical foliage or seasonal food scarcity, common in temperate zones, prevents them from acquiring the energy needed for survival. Poor thermoregulation and inflexible energy acquisition make modern sloths’ existence outside the tropics untenable.