Do Sloths drink water?

You have probably never seen a sloth drinking water. In fact, very few people have! As a result, it has been assumed for centuries that sloths get all of the water they need from the fresh rainforest leaves that they eat, and few documented observations exist of either of the two sloth genera drinking in the wild.

We photographed a male brown‐throated sloth (Bradypus variegatus) lapping water from the surface of a river in Costa Rica. Our latest work ‘Sloths hanging out for a drink’ has just been published in the scientific journal Frontiers in Ecology and the Environment.

This sighting prompts many additional questions. For example, how widespread is drinking behavior and how frequently does it occur? Methods used to assess water retention in wild sloths suggest that this behavior seldom occurs, so drinking is likely a method of maintaining osmotic balance when faced with extreme ambient temperatures, low precipitation, or increased consumption of mature (ie drier) leaves.

If freshwater access is indeed important, there are further implications relating to the captive husbandry of sloths in zoos and rescue centers (where they often face drier climes, typically don’t have access to water, and have a very low survival rate), and for conservation, especially after habitat fragmentation, where changes in land use can restrict water access (eg irrigation diverting stable water sources, roads that are difficult for strictly arboreal animals to cross).

Moving forward, the predicted trend toward a hotter, drier climate for Central and South American rainforests may negatively impact the sloths’ potentially delicate water balance, particularly in view of their limited energy budget and inability to travel long distances. If all sloths need a drink from time to time to stay healthy, it’s important to make sure they can get one.

-Dr. Rebecca Cliffe