Generally dull-plumaged birds, puffbirds may have brightly colored bills, eyebrows and irises. They have large heads, short wings and strong bills, with short legs and diminutive feet. There is some sexual dimorphism the female is slightly larger and slightly duller-plumaged than the male. Juvenile birds have shorter beaks. Puffbirds are one of the most silent birds in the Neotropics and vocalize very rarely. The most vocal species are the numbirds and those in the genus Nystalus. When calling they mostly do so at dawn and dusk. The main vocalizations consists of repeated and high-pitched whistles. The nunbirds are the most vocal of the family they have a wide repertoire of calls and often give very loud shouts.