Aramides cajaneagrey-necked wood rail(Also: grey-necked wood-rail)

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Geographic Range

Gray-necked wood-rails (Aramides cajanea) are widely distributed throughout the Neotropical region. These birds are found in the Pacific arid slope, from southern Sonora, south to Guanacaste, as well as Costa Rica, on islands in the southern Caribbean, such as Trinidad and Tobago, west of the base of the Andes Mountains, as well as the eastern parts of Brazil, Bolivia and Paraguay. They are found as far north as the eastern slope lowlands, from the border of the United States and Mexico to the Colombian border of Panama and as far south as the southeastern part of Brazil. (Stotz, et al., 1996)

Habitat

Gray-necked wood-rails are found in four distinct habitats, including three types of forest. These birds are commonly found in flooded tropical evergreen forests, which are flooded either permanently or annually. Less often, A. cajanea are found in gallery forests, which are also quite damp, swampy environments occurring along bodies of water. Likewise, Aramides cajanea also inhabits freshwater marshes, which have less dense vegetation than their forest habitats. Gray-necked wood-rails are also occasionally found in mangrove forests, which border lagoons, estuaries and rivers along the Pacific coast and are also flooded either permanently or occasionally. (Stotz, et al., 1996)

In forest vegetation these birds are usually found in lower tropical elevation zones (lower than 500 m), but can be found as high as 1,200 m. On rare occasions, Aramides cajanea have been found on mountains, in elevation as high as 2,300 m. (Stotz, et al., 1996)

  • Range elevation
    2,300 (high) m
    ft

Physical Description

In general, rails have relatively thin bodies; this helps them move through dense vegetation. As their common name suggests, gray-necked wood-rails can be distinguished from other rails by their distinct gray neck and head. Aramides cajanea has a powerful, yellow bill, red eyes and long red legs. The upper parts of their feathers are olive-brown, while their rump, tail and vent are black. Their breast and flanks are brownish-red, like rust. Their average length is 38 cm. Unlike some of its relatives, this bird is flighted due to its large pectoral muscles. Males and females are indistinguishable by their physical characteristics. ("Grey-necked Wood-rail Aramides cajaneus", 2012; Garrigues and Dean, 2007; Gosler, 2007; McNab, 1994; Skutch, 1994)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    397 g
    13.99 oz
  • Average length
    38 cm
    14.96 in
  • Average basal metabolic rate
    276 cm3.O2/g/hr

Reproduction

In an observational study of a pair of gray-necked wood-rails, a male and female bird occupied their nest at different times of day during the incubation period, which suggests a monogamous mating system. In general, most rails are thought to be monogamous. (Harris, 2009; Skutch, 1994)

Breeding begins during the first part of the rainy season, spanning from April to August. Most of what is known about their reproductive behavior is derived from a few anecdotal observations. In one such observation of nesting birds in the wild, one bird left the nest after an incubating session of between 6 to 8 hours and shortly thereafter, another bird took its place on the eggs, which was assumed to be the partner. During an observation in an aviary, the male incubated during the day and the female incubated at night. Data from both the aviary and the wild suggests that the incubation period is at least 20 days. In one study, the juveniles remained with their parents until at least 53 days old. (McNab and Ellis, 2006; Skutch, 1994)

  • Breeding interval
    Gray-necked wood-rails breed once yearly.
  • Breeding season
    Gray-necked wood-rails breed April to August.
  • Range eggs per season
    2.0 to 7.0
  • Average eggs per season
    5.0
  • Average time to hatching
    20 days
  • Average fledging age
    53 days

During the 53 days a juvenile spends with its parents, there is a great deal of parental investment, with one parent brooding at a time. As with incubation, parents share brooding responsibilities. The brooding parent brings food, carried inside their mouth or throat. A few days after the young hatch, the chicks are brought to a "nursery nest", until they are about 40 days old. Both males and females physically lure predators away from their eggs or nest. (Skutch, 1994)

Lifespan/Longevity

Their estimated lifespan is about 3.7 years in the wild. ("Grey-necked Wood-rail Aramides cajaneus", 2012)

  • Average lifespan
    Status: wild
    3.7 years

Behavior

Observations during breeding season found only one male and one female in any given area, indicating that Aramides cajanea is a solitary species. Unlike many other species of rails, gray-necked wood-rails are flighted. They can also be distinguished from other rails by their distinct song. (McNab, 1994; Skutch, 1994)

  • Average territory size
    13,600,000 km^2

Home Range

There is no information available on their home range.

Communication and Perception

Aramides cajanea has different types of calls and songs for different purposes. These birds issue a harsh, loud and powerful cackle when they feel threatened. These birds also have a unique song. Based on the song common to gray-necked wood-rails, they are often referred to by the first few notes of their song. The song of Aramides cajanea is heard from January to October, but most often around the nesting season, specifically April to June. During incubation, their song is not usually heard; mates are rarely together during that period and their song is a duet sung by mates. These birds sing most often during wet, cloudy weather and in the evening, although they do sing throughout the day when together. The duet notes are often strained or cracked, but they sing with almost perfect timing. Aramides cajanea also uses a clucking sound, similar to domestic hens, to call their chicks. (Skutch, 1994)

Food Habits

Aramides cajanea is an omnivorous bird. In their natural habitat, they have been seen eating maize and they are also avid frugivores. To eat these fruits, gray-necked wood-rails throw their whole bodies into pecking, see-sawing up and down, using their legs. Gray-necked wood-rails have also been observed eating water snakes and snails (Pomacea flagellata). They are also insectivorous and molluscivorous. (McNab and Ellis, 2006; Skutch, 1994)

  • Animal Foods
  • reptiles
  • insects
  • mollusks
  • aquatic crustaceans
  • Plant Foods
  • seeds, grains, and nuts
  • fruit

Predation

The loud, harsh cackle produced when Aramides cajanea is alarmed may be a type of behavioral adaptation to either warn other gray-necked wood-rails or startle predators. The only recorded predator of Aramides cajanea is humans, who are known to occasionally eat them due to their relative abundance. (Nishizawa and Uitto, 1995; Skutch, 1994)

Ecosystem Roles

This type of bird is often caught and eaten by humans. Their eggs may also be subject to predation, although the identity of their predators is not known. (Nishizawa and Uitto, 1995; Skutch, 1994)

Economic Importance for Humans: Positive

Adults and juveniles taken from the wild are used as both pets and food. Gray-necked wood-rails are pets both locally and internationally, while their use as food is primarily limited to their native areas. ("Grey-necked Wood-rail Aramides cajaneus", 2012; Nishizawa and Uitto, 1995)

Economic Importance for Humans: Negative

There are no known adverse effects of Aramides cajanea on humans.

Conservation Status

Conservation priority of Aramides cajanea is considered low because this species has a wide distribution throughout South America; likewise, they are habitat generalists and may use non-threatened habitats. As a non-threatened species, gray-necked wood-rails have a low research priority. ("Grey-necked Wood-rail Aramides cajaneus", 2012; Stotz, et al., 1996)

Other Comments

There are eight subspecies of gray-necked wood-rails, although they are not usually referred to specifically in the literature, they are worth noting. The subspecies are characterized by their geographic locations. The eight subspecies are: Aramides cajanea mexicanus, Aramides cajanea albiventris, Aramides cajanea vanrossemi, Aramides cajanea pacificus, Aramides cajanea plumbeicollis, Aramides cajanea latens, Aramides cajanea morrisoni, and Aramides cajanea cajanea. (Clements, 2007)

Contributors

Marissa Falkiewicz (author), The College of New Jersey, Matthew Wund (editor), The College of New Jersey, Leila Siciliano Martina (editor), Animal Diversity Web Staff.

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

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.

chemical

uses smells or other chemicals to communicate

choruses

to jointly display, usually with sounds, at the same time as two or more other individuals of the same or different species

duets

to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate

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.

female parental care

parental care is carried out by females

food

A substance that provides both nutrients and energy to a living thing.

forest

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

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).

male parental care

parental care is carried out by males

marsh

marshes are wetland areas often dominated by grasses and reeds.

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.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oviparous

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

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

seasonal breeding

breeding is confined to a particular season

sexual

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

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

young precocial

young are relatively well-developed when born

References

2012. "Grey-necked Wood-rail Aramides cajaneus" (On-line). Accessed October 10, 2012 at http://www.birdlife.org/datazone/speciesfactsheet.php?id=2884&m=1.

Clements, J. 2007. The Clements Checklist of Birds of the World. Ithaca: Cornell University Press.

Garrigues, R., R. Dean. 2007. The Birds of Costa Rica. Ithaca: Comstock Publishing Associates.

Gosler, A. 2007. Birds of the World: A Photographic Guide. Buffalo: Firefly Books Inc.

Harris, T. 2009. Complete Birds of the World. Washington D.C.: National Geographic.

McNab, B. 1994. Energy conservation and the evolution of flightlessness in birds. American Naturalist, 144/4: 628-642.

McNab, B., H. Ellis. 2006. Flightless rails endemic to islands have lower energy expenditures and clutch sizes than flighted rails on islands and continents. Comparative Biochemistry & Physiology Part A: Molecular & Integrative Physiology, 145/3: 295-311.

Nishizawa, T., J. Uitto. 1995. The Fragile Tropics of Latin America. Tokyo: United Nations University Press.

Skutch, A. 1994. The gray-necked wood-rail: habits, food, nesting, and voice. The Auk, 111: 200.

Stotz, D., J. Fitzpatrick, T. Parker III, D. Moskovits. 1996. Neotropical Birds: Ecology and Conservation. Chicago: The University of Chicago Press.