Much like owls, this species is nocturnal. They prey on large insects and small vertebrates, which they capture in sallies from high perches.
Possibly its most well-known characteristic is its unique moaning growl that the Great Potoo (Nyctibius grandis) vocalizes throughout the night, creating an unsettling atmosphere in the Neotropics with its nocturnal sounds. This nocturnal predator is usually seen perched high above the ground while foraging; hawking when prey is spotted. After the pounce, the Potoo almost always returns to its previous perch. Normally, during the day it perches upright on a tree stump, and is overlooked because it resembles part of the stump; this is a camouflage, not just by coloration, but also camouflage by the setting. The Great Potoo can be located at night by the reflection of light from its eyes as it sits vertical on a post, roost, or angled-tree trunk.