How can a three-toed sloth's buried feces benefit its favorite tree?

The three-toed sloth (Bradypus variegatus) provides a significant nutritional benefit to its "modal" tree—the specific tree where it spends most of its time—by burying its feces at the base of the trunk.1

By descending to the ground to dig a pit and covering its waste with leaf litter, the sloth ensures that these nutrients are delivered directly to the tree's root system. If the sloth were to defecate from the canopy, the nutrients would be scattered, forcing the tree to share this resource with epiphytic plants growing on its branches and with competing vegetation on the forest floor. By concentrating this waste at the base, the tree can efficiently absorb up to half of the nutrients the sloth consumes, which are then recycled into new foliage that the sloth eventually eats. Additionally, insects such as pyralid moths that live in the sloth's fur may lay eggs in the dung, and their larvae may further assist in this nutrient-recycling process.1