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= Grey-cowled wood rail =
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Introduction
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The grey-cowled wood rail or grey-necked wood rail ('Aramides
cajaneus'; also gray-) is a species of bird in the family Rallidae,
the rails. It lives primarily in the forests, mangroves, and swamps of
Central and South America. Of the two subspecies, 'A. c. avicenniae'
is found in southeastern Brazil, while the nominate is found
throughout the portion of the range not occupied by the other
subspecies. The species as a whole is usually found at elevations from
sea level to 2000 m, although some have been found above that. This
bird's large range, along with its significant population, is why it
is considered to be least-concern by the International Union for
Conservation of Nature (IUCN). In some places, it is occasionally
hunted and kept for food.
This bird, large for a wood rail, has both a grey head and neck. In
the nominate, the back of the head has a brown patch. The are
olive-green to dark brown. The chest and flanks are a rufous colour,
with the belly, rump, and tail being black. The legs are coral-red,
the bill is a bright greenish-yellow, and the eyes are red. The sexes
are similar. The juveniles can be differentiated by their duller look,
and the chicks have a black, downy appearance, brown head, and black
beak. The subspecies 'A. c. avicenniae' can be differentiated by its
smaller size, lack of a brown patch at the back of the neck, and its
lower back being toned slightly olive. The are also pale.
The bird is monogamous; pairs can be found together throughout the
year. During the breeding season, which usually lasts from March to
August, the grey-cowled wood rail builds nests that can be found on
flat branches and in thickets, usually at heights between 1 and. In
these nests, there is a clutch consisting of three to seven eggs,
incubated by both sexes. The chicks that hatch are precocial, able to
move soon after hatching. This rail feeds on a wide range of foods,
from molluscs to seeds. It is also known to feed on the faeces of
giant otters.
Taxonomy and etymology
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Placed in the family Rallidae (rails, moorhens, coots and allies),
this species was originally described as 'Fulica cajanea' by Philipp
Ludwig Statius Müller, in his 1776 'Vollständiges Natursystem'. Müller
based his description on the illustration (water hen of Cayenne) by
the French naturalist and artist Edme-Louis Daubenton in his 'Planches
Enlumineés d'Histoire Naturelle'. It was eventually moved to the new
genus 'Aramides', the wood rails, by Jacques Pucheran in 1845, and the
specific epithet was changed to 'cajaneus'.
The grey-cowled wood rail is regarded as being sister species with the
russet-naped wood rail, one of the nine members of the genus
'Aramides', within which the grey-cowled wood rail is also included.
The two were classified as subspecies of a single species by James L.
Peters in the 1934 edition of his 'Check-list of Birds of the World',
before being separated as species once more in 2015. The two rails
have different calls and plumage with no gradation reported. The
number of subspecies is contentious, some authorities accept up to
nine, while others accept only two. It is even suggested that the
subspecies 'A. c. avicenniae' be split off as a full species, based on
differences in morphology and calls, speculated to have arisen because
the slaty-breasted wood rail acted as an ecological barrier between
the two subspecies. The subspecies, according to the International
Ornithologists' Union, are:
* 'Aramides cajaneus cajaneus' (Müller, 1776) - from Costa Rica to
Colombia, east through Venezuela and Trinidad to Brazil, and south to
Northern Argentina and Uruguay
* 'A. c. avicenniae' Stotz, 1992 - coastal southeastern Brazil
Etymology
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The genus name 'Aramides' is derived from the combination of the genus
name 'Aramus' and of the Greek 'oidēs', "resembling". This refers to
the similarity between birds of the genus 'Aramides' and the one
species of the genus 'Aramus'. The specific epithet, 'cajaneus', is in
reference to Cayenne, the capital city of French Guiana. The
subspecies epithet 'avicenniae' honours the Persian philosopher
Avicenna.
Description
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The grey-cowled wood rail usually measures 33 - long and weighs 320 -,
particularly large for a wood rail. The are olive-green to dark
brown. The head and neck are medium-grey, blending into a brown patch
at the back of the head. The eyes are red. The chest and flanks are
rufous. The belly, rump, and tail are black. The legs are coral-red,
while the bill is a bright greenish-yellow. The males and females are
similar.
Juvenile birds are similar to the adult but are duller in colour, with
their belly sooty-black and flecked with buff. The juveniles also
differ in that their bill and legs are dusky, and have brownish eyes.
The chicks are black and downy, with a brownish head. Their dark eyes
are lined with dull, reddish bare skin. The black bill has a
flesh-coloured base, and a small, white behind the tip of the , as
well as a very small one at the tip of the .
The subspecies 'A. c. avicenniae' differs from the nominate by its
smaller size. It also varies as its nape to back is a dull grey
colour. The brown spot present at the back of the head of the nominate
is also reduced or gone. The lower back is toned a slight olive, and
the underparts are also slightly paler than the nominate, but without
white feathers. The upper wing coverts of 'A. c. avicenniae' are also
more greenish-grey. The similar but smaller rufous-necked wood rail
can be differentiated from the grey-necked wood rail by the former's
reddish head and neck with a grey upper back.
This bird its simultaneously. This moult occurs during the months
from March to June.
Voice
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The grey-cowled wood rail has a loud, repetitive cackling call mainly
heard at dawn and dusk: 'pop-tiyi pop-tiyi co-co-co-co-co' or 'chitico
chitico cao-cao-cao'. These songs are often sung in a chorus or duet.
The is a harsh, loud cackle or clucking shriek. The 'chitico chitico
cao-cao-cao' call made by this rail is similar to the brown wood
rail's 'kui-ko' call.
Distribution and habitat
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The grey-cowled wood rail is found in Argentina, Bolivia, Brazil,
Colombia, Costa Rica, Ecuador, French Guiana, Guyana, Panama,
Paraguay, Peru, Suriname, Trinidad and Tobago, Uruguay, and Venezuela.
The nominate subspecies is cut off by the Andes Mountains and lives
east of the range in Ecuador, Peru, and Bolivia; it is not found in
the southeastern interior of Brazil. The subspecies 'A. c. avicenniae'
is found in coastal southeastern Brazil, around São Paulo.
The grey-cowled wood rail's natural habitats are subtropical or
tropical moist lowland forests, subtropical or tropical mangrove
forests, and subtropical or tropical swamps. The subspecies 'A. c.
avicenniae' is however almost completely restricted to mangrove
forests. The grey-cowled wood rail can be found from sea level to
elevations around 2000 m, although some wanderers have been recorded
at elevations up to 2300 m in Colombia.
Behaviour and ecology
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This bird can be seen to perch in both shrubbery and even trees,
something characteristic of the forest rails. The grey-cowled wood
rail rarely flies, although when it is flushed out, it will generally
move to a branch close to the ground. If it is being observed, it is
generally cautious.
Breeding
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The grey-cowled wood rail's nests are situated in trees and bushes,
usually 1 to 3 metres (3.3 to 9.8 ft) off the ground, built on flat
branches or in thickets and lined with twigs and leaves. They
generally have a diameter between 30 and on the outside, with an
internal diameter of around 15 cm. The depth is usually between under
4 and. The overall height of the nest is around 16 cm.
This bird is monogamous, forming long-lasting pair bonds, with pairs
of grey-necked wood rails staying together throughout the year. Its
breeding season usually occurs between March and August, although this
varies depending on geography. In Costa Rica, the breeding season
extends until September. In Mexico, on the other hand, the breeding
season is known to start as early as January. In captivity, this wood
rail is territorial.
The clutch the grey-cowled wood rail lays usually consists of three to
seven brown-blotched, slightly glossy, whitish eggs, although clutches
consisting of five eggs are most typical. These eggs usually measure
around 52 by and weigh between 25.1 and. They are incubated by both
sexes, each taking six to eight hour shifts, for around 20 days. In
captivity, the male incubates during the day, and the female during
the night. The chicks hatch precocial and are cared for by the parents
for one or two days before leaving the nest, although chicks sometimes
use the brood nest until they are 40 days old.
Feeding
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This bird feeds at night, eating various invertebrates and small
vertebrates. While in mangroves, it commonly feeds on crabs.
Otherwise, it will generally feed on molluscs (such as snails,
including 'Pomacea flagellata'), arthropods, frogs, seeds, grains,
leaves, berries, palm fruits, and the occasional water snake. Maize,
rice, and bananas are also viable food items for the grey-necked wood
rail. It is also known to feed on the feces of giant otters at
latrines.
When eating snails, this rail will hammer at the shells to extract
them. For berries, it will jump high to break off clusters of this
fruit. After doing this, it will pick off the berries one by one and
eat them. It uses its partially open bill to probe and move aside
debris like leaf litter. It is generally wary and secretive, and
selfish when mated. This manifests in warning its partner with threat
displays to keep it at a distance. Even so, it has occasionally been
seen to openly forage in short grass near thickets and in streams or
muddy tracks.
Parasites
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The grey-cowled wood rail is the type host of 'Plasmodium bertii', an
apicomplexan parasite, meaning that 'P. bertii' was originally
discovered on this organism. 'P. lutzi' is also found on this bird.
Status
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This rail is considered to be a least-concern species, according to
the IUCN. The justification is this species' stable and large
population, believed to be somewhere between five million and 50
million individuals. The grey-cowled wood rail also has a large extent
of occurrence, estimated to cover 21.4 km2. It is common throughout
its range, although it is adversely affected by destruction of its
habitat.
Human interaction
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The grey-cowled wood rail is occasionally hunted for food in northeast
Brazil. They are usually hunted with baited fish hooks that are laid
near the bodies of water where these birds forage. In the Las Minas
District, Panama, this bird is also kept for food. Although it is
generally cautious, it can tolerate an approach by humans up to about
10 m away from it, after which it will retreat into the undergrowth.
External links
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*
*
*
[https://sta.uwi.edu/fst/lifesciences/sites/default/files/lifesciences/images/Aramides%20cajaneus%20-%20Grey-necked%20Wood-rail.pdf
"Aramides cajaneus (Grey-necked Wood-rail)"] in 'The Online Guide to
the Animals of Trinidad and Tobago'
License
=========
All content on Gopherpedia comes from Wikipedia, and is licensed under CC-BY-SA
License URL: http://creativecommons.org/licenses/by-sa/3.0/
Original Article: http://en.wikipedia.org/wiki/Grey-cowled_wood_rail
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