Aramides cajanea

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.

• Biogeographic Regions
• neotropical neotropical
  • native native

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.

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.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest

• Wetlands
• marsh marsh

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.

• Other Physical Features
• endothermic endothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

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.

• Mating System
• monogamous monogamous

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.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

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.

• Parental Investment
• precocial precocial
• male parental care male parental care
• female parental care female parental care
• pre-hatching/birth
  • protecting
    • male
    • female
• pre-weaning/fledging
  • provisioning
  • protecting
• pre-independence
  • provisioning
  • protecting

Lifespan/Longevity

Their estimated lifespan is about 3.7 years in the wild.

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.

• Key Behaviors
• arboreal arboreal
• terricolous
• flies
• glides
• motile motile

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.

• Communication Channels
• acoustic acoustic

• Other Communication Modes
• duets duets
• choruses choruses

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

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.

• Primary Diet
• omnivore omnivore

• 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.

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.

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.

• Positive Impacts
• pet trade pet trade
• food food

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.

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 .

Additional Links

Encyclopedia of Life

Contributors

Marissa Falkiewicz (author), The College of New Jersey, Matthew Wund (editor), The College of New Jersey, Leila Siciliano Martina (editor), Texas State University.

References

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., 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.

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

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.

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 .