The Great Jacamar is a large, striking bird of the canopy of humid lowland forests. By far the largest of the jacamars, it has glossy green upperparts, extensively rufous underparts, a rounded tail, and a long, thick black bill. Its song is a strong, whistled "kleee'uuuuuuuuu", typically with a break in the middle, and is often the first clue to its presence. The Great Jacamar can be difficult to spot as it often sits in one spot in the canopy for long periods. Here, it preys on insects by sallying after them and then beating them against a branch before consumption. Nests have been found in arboreal termitaria and in a rotting tree trunk.