Potoos

(Nyctibiidae)

Class Aves

Order Caprimulgiformes

Suborder Caprimulgi

Family Nyctibiidae

Thumbnail description
Medium-sized, cryptically colored, nocturnal birds with large head, poorly developed facial bristles, long wings and tail, and short legs

Size
8–23 in (21–57 cm); 1.6–22 oz (46–624 g)

Number of genera, species
1 genus; 7 species

Habitat
Forest, woodlands, wooded savannas

Conservation status
Not threatened

Distribution
Central and South America from Mexico to Uruguay, Hispaniola, and Jamaica

Evolution and systematics

Potoos are a well-defined group of Caprimulgiformes that are now restricted to the Neotropics. They are perhaps most closely related to the true nightjars of the family Caprimulgidae, from which they appear less distinct than do the owletnightjars (Aegothelidae) or frogmouths (Podargidae). A fossil leg bone from the early Tertiary (Upper Eocene or Oligocene) of France demonstrates the antiquity of potoos and also that they formerly had a much more extensive range.

Although the seven species are normally placed within a single genus they differ markedly in size and color, with small rufous potoos (Nyctibius bracteatus) being only a tenth the mass of great potoos (N. grandis), so that taxonomists may eventually subdivide the genus. Some specimens of northern potoos (N. jamaicensis) and gray potoos (N. griseus) are almost identical in external appearance; the division into two separate species had to await description of the striking differences in their voices.

Physical characteristics

Potoos have a small body, a disproportionately large head with large eyes, a small but wide-based bill with a huge gape, long rounded wings, a long tail, and proportionately very small legs and feet. Except in the rufous potoo, facial bristles are less developed than in most other Caprimulgiformes. Unlike true nightjars, potoos lack comb-like serrations on the claw of the middle toe.

Plumage coloration involves the drab hues and cryptic patterns found in other Caprimulgiformes, with gray, buff, rufous, or brown dominant in different species. Several of the smaller potoos have bold white spots or wing patches, but the two largest species are rather uniformly colored with closely barred and streaked patterning.

Distribution

Most potoo species are found in tropical South America, but the overall range of the family extends from subtropical areas in Mexico, Hispaniola, and Jamaica south to southern Brazil and Uruguay. All species are thought to be sedentary.

Habitat

Potoos are mainly forest birds, with different species characteristic of lowland or montane forests. Several species

extend into woodlands, plantations, or even groves of trees in savannas or partly deforested areas.

Behavior

Potoos spend daylight hours almost motionless on a branch or tree stump, where their immobility and cryptic coloration render them almost invisible. When disturbed they reinforce the camouflage by flattening their plumage and adopting an erect concealment posture so that their outline merges with that of a snag on a branch or the top of a stump. Although birds thus concealed have their eyelids closed, two small notches in the eyelids (the so-called magic eyes) allow vision without spoiling the bird's camouflage by opening the large shiny eyes.

If undisturbed, activity occurs only from dusk until dawn, when the birds sing and hunt from exposed perches and fly about their territories. They are most conspicuous by their loud songs, which are different in each species and vary from a long whistled glissando in the white-winged potoo (Nyctibius leucopterus) to a loud guttural snoring in the great potoo.

Singing birds approach aggressively when recordings of their songs are played, suggesting that the songs function in advertisement and defense of territories.

Feeding ecology and diet

The main food items of potoos are flying insects, particularly beetles, moths, orthopterans, and termites. There are a few records of the larger potoos (great potoos) taking small bats, and once a small bird (white-throated seedeater, Sporophila torqueola) was found in the stomach of a northern potoo. Prey is captured by sallying flights from exposed perches such as tree stumps, branches, or fence posts. Prey items are mainly caught in the air, less often taken from vegetation, and apparently not taken from the ground.

Reproductive biology

Potoos are monogamous. They do not build a nest; instead a single egg is laid in a natural hollow on top of a branch or on a high tree stump. The egg is oval-elliptical or elliptical with white color and spots of brown or gray. Incubation and care of the young is carried out by both sexes, although details are poorly known. The few data on the incubation period show that it may last 30–33 days in the gray potoo, which has fledging periods of 40–51 days. The larger great potoo has a fledging period of at least 55 days. Young have pale down when hatched. Adult birds incubating eggs

or brooding small young freeze in place when disturbed so that they blend in well, like potoos at their normal daytime roosts. By the time nestlings have most of their early down replaced by juvenal feathers they are no longer brooded by a parent and they also freeze if disturbed.

Conservation status

No potoo species is regarded as globally threatened, but several have suffered large declines in populations as a result of deforestation. In particular, populations of white-winged potoos in the forests of the Bahia region of southeastern Brazil must now be endangered if they are not already extinct, and the widespread long-tailed potoo (Nyctibius aethereus) is reported to be rare in most parts of its range.

Significance to humans

Potoos have little economic importance. Their loud nocturnal voices are well known to local people, although potoos' calls are often attributed to other animals such as sloths. Potoos formerly figured in superstitions and folklore at least in rural Brazil, where the melancholy song of gray potoos was believed to be a sad lament from the reincarnation of one of a pair of separated, widowed, or unrequited lovers. The harsher voice of the great potoo, on the other hand, was sometimes considered a sign of bad luck or impending death.

Species accounts

List of Species

Rufous potoo

Nyctibius bracteatus

taxonomy

Nyctibius bracteatus J. Gould, 1846, Colombia. Monotypic.

other common names

English: Colombian potoo; French: Ibijau roux; German: Tropfentagschläfer; Spanish: Nictibio rufo.

physical characteristics

8.3–9.8 in (21–25 cm); 1.6–2.0 oz (46–58 g). Coloration is atypical for a potoo. Overall the bird is deep orange-rufous with large white spots bordered in black; long bristles spring from the loral area. Sexes similar.

distribution

South America from Colombia and Guyana south to eastern Peru and northern Brazil.

habitat

Lowland rainforests.

behavior

A little-known, nocturnal bird of the forest understory and middle story.

feeding ecology and diet

Catches insects on sallying flights from a perch.

reproductive biology

Only nest reported was on top of a broken palm stub inside forest, with a single blotched egg. Nestling was later tended by both parents and fledged before reaching adult size.

conservation status

Probably not threatened overall, but undoubtedly declining due to forest destruction.

significance to humans

None known.

Gray potoo

Nyctibius griseus

taxonomy

Caprimulgus griseus Gmelin, 1789, Cayenne. Two subspecies.

other common names

English: Common potoo; French: Ibijau gris; German: Urutau-Tagschläfer; Spanish: Nictibio urutaú.

physical characteristics

13–16 in (33–41 cm); 5–7 oz. (145–202 g). Plumage varies from reddish brown to gray-brown. Sexes are similar.

distribution

Central and South America from Costa Rica and Panama south to Uruguay.

habitat

Forest, woodland, plantations, and savanna with scattered trees.

behavior

Roosts singly and quietly on branch during day. Active at night, when song of four to seven whistled notes is emitted.

feeding ecology and diet

Feeds on insects, including beetles, moths, grasshoppers, bugs, and termites, caught by sallying from perch.

reproductive biology

Lays single egg in depression in sloping branch or near forking branches. Incubation by both sexes, lasts for 30–33 days. Young brooded by either parent when small, fledging period variously estimated as 40–51 days.

conservation status

Not threatened.

significance to humans

Like other potoos, the subject of myths and superstitions in some rural areas.

Great potoo

Nyctibius grandis

taxonomy

Caprimulgus grandis Gmelin, 1789, Brazil and Cayenne. Two subspecies.

other common names

English: Grand potoo; French: Grand ibijau; German: Riesentagschläfer; Spanish: Nictibio grande.

physical characteristics

19–23 in (48–57 cm); 12.7–22 oz (360–624 g). The largest member of its genus. Overall color ranges from buff-brown to nearly white; the palest and most variable species of potoo. Sexes are similar.

distribution

Central and South America from southern Mexico to southeastern Brazil.

habitat

Forests, woodlands, and plantations.

behavior

Roosts high in trees during day, active at dusk and during night. Calls most actively on moonlit nights, giving loud

guttural snoring sound from perch that functions in territorial defense.

feeding ecology and diet

Sallies for flying prey from an exposed perch, taking mainly insects such as beetles and moths, but sometimes also small bats.

reproductive biology

Clutch of a single egg is laid in depression in branch of tree. Incubation by both sexes reported, period unknown. Fledging period of one nestling was at least 55 days.

conservation status

Not threatened overall, but has doubtless declined in many regions because of deforestation.

significance to humans

Subject of mythology and superstition in rural areas.

Resources

Books

Cohn-Haft, M. "Family Nyctibiidae (Potoos)." In Handbook of Birds of the World. Vol. 5, Barn-owls to Hummingbirds, edited by Josep del Hoyo, Andrew Elliott, and Jordi Sargatal. Barcelona: Lynx Edicions, 1999.

Holyoak, D.T. Nightjars and Their Allies. Oxford: Oxford University Press, 2001.

Skutch, A. "Common Potoo." In Birds of Tropical America. Austin: University of Texas Press, 1983.

David T. Holyoak, PhD