Chelidoptera tenebrosa are quiet and cautious birds that often return to the same perch or nesting spot. They usually glide in semicircles with slow wingbeats and are observed resting on dry bushes near open areas. Adults are highly attentive and take turns caring for eggs and chicks, even cleaning the nest by swallowing droppings. Their call is a quick, three-syllable sound, often ending in trills.

During the breeding season, they can become aggressive towards other birds and occasionally receive help from a third adult when feeding chicks. Young are very alert to sound, often crawling to the nest entrance even while still blind. After the breeding season, these birds may gather in flocks of up to 30 individuals.

They prefer sandy riverbanks, swamp edges, and open areas near forests or palm groves. They are also found in clearings, secondary forests, and even abandoned gardens.

We found nests in Alto Parnaíba, Maranhão (4 nests) and Caseara, Tocantins (1 nest).

Swallow-winged Puffbirds breed during October and November in these regions.

The nest is a visible ground cavity dug by the adults, usually located in flat, open terrain. Nests have been found in abandoned gardens, clearings, and open fields next to trees.
The tunnel entrance is about 5 cm wide and extends between 80 cm to 1 meter underground, with the nesting chamber around 20 cm below the surface.