Dusky-billed parrotlets prefer lowland tropical rainforest edges and clearings, riparian zones, secondary habitats, and savanna.

Unlike many members of the genus Forpus, they are not captured for the parrot trade, and they are relatively unaffected by deforestation.

[2] Dusky-billed parrotlets' diet consists of approximately 10% seeds, buds, and blossoms and 90% berries and fruits,.

However, because the name modesta was assigned to at least two closely related birds of the genus Psittacula, the dusky-billed parrotlet was reverted to F. sclateri.

[6] It has been suggested that the dusky-billed parrotlet is basal to all other species of the genus Forpus based on diversification and speciation rates and patterns.