Active sloths swivel their heads to look around very carefully before deciding which leaves to approach for feeding. Female sloths that are pregnant or carrying a young one often choose to feed on leaves of Lacmellea panamensis, which is one of the most easily digestible to sloths. Pregnant sloths also prefer Cecropia eximia , but mainly in August through December. However, females with young do not very often use Cecropia, which is not as digestible as Lacmellea. To speed up their life processes, three-toed sloths in particular will hang out in the sun in the morning, exposing their bellies for deep body warming, and will often choose trees to sleep in that will give them good basking sites in the morning.
Sloth mothers give birth to one baby once a year, after a six month pregnancy.
The young one is weaned from milk after about six weeks, but continues to ride on the mother for another five months. During this time the young sloth learns from its mother which leaves are to be eaten, where to find shelter, and where edible trees are located. Until six months old, the young one keeps at least one foot on its mother while reaching for leaves to eat, until finally the mother just moves away and keeps on going to another part of her home range. Two-toed sloths like to sleep in tangles of lianas in trees, as do other arboreal mammals such as squirrels. These tangles provide concealed spaces but also act as early warning systems against approaching predators.