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Nyctibius grandisgreat potoo

By Grant Slusher

Geographic Range

Great potoos are neotropical birds found throughout Central America from as far north as southern Mexico to as far south as Bolivia. (Grzmek, 2002; Rangel-Salazar and Vega-Rivera, 1989)

Habitat

Great potoos live primarily in forests and rainforests but have also been found in forest edge habitat and on and around farmlands. During they day they are usually found either perched or nesting at least 12 m above ground level in larger trees, usually on branches that are approximately 20 to 30 cm in diameter. At night they may move to lower perches, as low as 1.5 m above the ground, from which they hunt. (Grzmek, 2002; Haverschmidt, 1948; Vanderwerf, 1988)

  • Range elevation
    35 to 2900 m
    114.83 to 9514.44 ft

Physical Description

Great potoos have relatively large heads in relation to their bodies. They have large eyes with a light brown to yellow iris and beaks that are short but broad, giving them a very large gape. In comparison to other Caprimulgiformes, the facial bristles are diminished to non-existent. They have elliptical wings with an elongate tail that aides in steering during noiseless landings on tree branches. The plumage is white to grayish with marbled black and burgundy tones. Tail coloration matches that of the body, with the exception of the 8 or 9 white bars that extend laterally across it. (Borerro, 1974; Grzmek, 2002; Land and Schultz, 1963)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    360 to 650 g
    12.69 to 22.91 oz
  • Range length
    480 to 600 mm
    18.90 to 23.62 in
  • Range wingspan
    700 to 804 mm
    27.56 to 31.65 in
  • Average wingspan
    734.8 mm
    28.93 in

Reproduction

Great potoos are monogamous breeders with no dimorphism between the sexes. In fact, the sexes are so similar that time budgeting at the nest per sex has not been determined. (Vanderwerf, 1988)

Nesting season in great potoos has been observed from June through August in Venezuela and November in Surinam (these are each the approximate wet seasons for those areas). Only one egg is laid per clutch, and little is known of the incubation period. Great potoos do not build nests, rather nests are simply deeper notches in larger branches of their roosting trees. Hatching in great potoos has not been well documented but only one parent is present at the nest per incubation. Weight at hatching is also questionable with the youngest observed nestling mortality weighing 220g. Time to fledging has been determined to be 55 days after hatching. Chicks develop quickly with body feathers appearing through down feathers approximately two weeks after hatching. Five weeks after hatching chicks are almost 2/3 the length of the parents. Chicks begin leaving the nest and investigating the nesting branch one month after hatching. After a month and a half adults no longer return during the day to tend to young. Instead the only interactions between parent and offspring are after dark, which probably includes feeding behavior. At just under two months offspring have usually left the nest without returning to roost during the day. (Haverschmidt, 1948; Vanderwerf, 1988)

  • Breeding interval
    Great potoos produce one egg per year, usually during the rainy season.
  • Breeding season
    Breeding season occurs during the rainy season which varies by region in South America.
  • Average eggs per season
    1
  • Average fledging age
    55 days
  • Range time to independence
    1.5 to 2 months

Both male and female great potoos incubate eggs at the nest during the day. During incubation it has been noted that at no point were both parents simultaneously at or around the nest. After the eggs have hatched both parents hunt at night and return to the nest to provision young with prey items. Provisioning continues until offspring have fully fledged and permanently leave the nest. (Young and Zook, 1999)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female
    • protecting
      • male
      • female

Lifespan/Longevity

Because of the elusive nature of great potoos, little is known about their longevity and life span. The only documented mortalities were of unknown causes and in one instance a person had shot an adult from a tree. (Haverschmidt, 1948)

Behavior

Great potoos are a solitary species with the only observed social interactions being between parents and young during parental care and provisioning. Great potoos are nocturnal, with a majority of their activity at night focused on catching and consuming prey items including large flying insects and sometimes bats. Feeding includes sallying flights from lower perches then returning to the perch to consume prey items. Prey is usually caught from the air by engulfing it in their large gape. During the day they are extremely still, and usually find a higher perch if they are not in their nesting spot. They avoid movement presumably to enhance the effectiveness of their cryptic coloration. During nesting they reduce their movement to a minimum unless disturbed by possible threats, after which they freeze which is assumed to be predation vigilance. Grooming behavior is distinct in that great potoos scratches their heads by moving the foot up and over the wing instead of coming up from beneath the wing. (Grzmek, 2002; Haverschmidt, 1948)

Home Range

Great potoos only ever venture away from their roosting area when they hunt. Their hunting perches are usually in close proximity to their day time roosts. The size of these home ranges is not known. (Haverschmidt, 1948)

Communication and Perception

Vocalizations in great potoos take place mostly at night and are assumed to be a way of communicating territorial boundaries to other great potoos. The repertoire of vocalizations includes a deeper, frog-like "baaaao" and an eerier "whoap". Between the two different calls the "whoap" occurs more often, and has been heard from both birds that are perched and in flight. In rare instances clicking noises have been heard, but their purpose is unknown. (Slud, 1979)

Food Habits

Great potoos are carnivores that hunt nocturnal, flying prey items in the air at night, most frequently large insects and sometimes bats. They usually find a lower perch to fly from and then return to the perch to consume the prey item. (Grzmek, 2002; Haverschmidt, 1948)

  • Animal Foods
  • mammals
  • insects

Predation

Great potoos are relatively large birds with highly cryptic coloration. During the day great potoos remain relatively motionless, and upon disturbance completely freeze in increase vigilance. The known predators of great potoos include monkeys (Cebus, Ateles geoffroyi, and Alouatta palliata), tayras (Eira barbara), and collared forest falcons (Micrastur semitorquatus). Parents are present at the nest during the day and use their cryptic coloration to camouflage the nesting hole. (Young and Zook, 1999)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Great potoos are a predatory species that prey on larger flying invertebrates and in some cases vertebrates, like smaller birds or bats. (Grzmek, 2002)

Economic Importance for Humans: Positive

Great potoos are of no real economic importance to humans, although they play an important role in their native ecosystems.

Economic Importance for Humans: Negative

There are no adverse effects of great potoos on humans.

Conservation Status

Currently great potoos are not of primary conservation concern. They inhabit a broad geographic region and are capable of long distance dispersal. It is suspected that the population has been drastically decreased with the reduction in forest area associated with slash and burn farming, but remaining populations are estimated to be large. (Grzmek, 2002)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Grant Slusher (author), Northern Michigan University, Alec R. Lindsay (editor, instructor), Northern Michigan University.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

polymorphic

"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

References

Borerro, J. 1974. Notes on the structure of upper eyelid of potoos.. The Condor, 76: 210-211.

Grzmek, B. 2002. Grzmek's Animal Life Encyclopedia. Pp. 395-400 in M Hutchins, J Jackson, W Bock, eds. Birds I-IV, Vol. 9, 2 Edition. Farmington Hills, Michigan: Thomson-Gale.

Haverschmidt, F. 1948. Observations on Nyctibius grandis in Surinam. Auk, 65: 30-33.

Land, H., W. Schultz. 1963. A proposed subspecies of the Great Potoo, Nyctibius grandis. Auk, 80: 195-196.

Rangel-Salazar, L., H. Vega-Rivera. 1989. Two new records of birds for southern Mexico. The Condor, 91: 214-215.

Slud, P. 1979. Calls of the Geat Potoo. The Condor, 81: 322.

Vanderwerf, E. 1988. Observations on the nesting of the great potoo (Nyctibius grandis) in central Venezuela. The Condor, 90: 948-950.

Young, B., J. Zook. 1999. Nesting of four poorly-known bird species on the Caribbean slope of Costa Rica. The Wilson Bulletin, 111: 124-128.

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