The
Anhinga (Anhinga anhinga), sometimes called Snakebird, Darter, American
Darter, or Water Turkey, is a water bird of the warmer parts of
North America and South America. The word "anhinga" comes
from the Brazilian Tupi language and means devil bird or snake bird.
It
is a cormorant-like bird with an average body length of 85 cm (35
in), a wingspan of 117 cm (45 in), and a weight of 1,350 g. It is
a dark-plumaged fish-eater with a very long neck, and often swims
with only the neck above water. When swimming in this style the
name Snakebird is apparent, since only the colored neck appears
above water the bird looks like a snake ready to strike.
The
Anhinga is a member of the darter family, Anhingidae, and is closely
related to Indian (Anhinga melanogaster), African (Anhinga rufa),
and Australian (Anhinga novaehollandiae) Darters.
The
Anhinga's feathers are not waterproofed by oils like those of ducks,
and can get waterlogged, causing the bird to become barely buoyant.
However, this allows it to dive easily and search for prey under
the water. It can stay down for significant periods. Anhingas eat
fish and amphibians.
When
necessary, the Anhinga will dry out its wings and feathers. It will
perch for long periods with its wings spread to allow the drying
process, as do cormorants. If it attempts to fly while its wings
are wet, it has great difficulty getting off the water and takes
off by flapping vigorously while 'running' on the water. Anhinga
will often search for food in small groups.
Distribution
and migration
The anhinga genus is found all over the world in warm shallow waters.
The American Anhinga has been subdivided into two subspecies - A.
a. anhinga and A. a. leucogaster - based on their location. A. a.
anhinga can be found mainly east of the Andes in South America and
also the islands of Trinidad and Tobago. A. a. leucogaster can be
found in the southern United States, Mexico, Cuba, and Grenada.
Only
birds that live in the extreme north and south of their range migrate
and do so based on temperature and available sunlight. Anhingas
will migrate towards the equator during winter but this range is
"determined by the amount of sunshine to warm the chilled birds".
Although not in their usual range, anhingas have been found as far
north as the states of Pennsylvania and Wisconsin in the United
States.
Kettles
of anhingas often migrate with other birds and have been described
as resembling black paper gliders.
Physical
description and taxonomy
The A. anhinga species is a large bird and measures approximately
35 in (88.9 cm) in length with a 45 in (1.14 m) wingspan. The A.
a. anhinga is larger than A. a. leucogaster and has "broader
buffy tail lips".3] The weight is 2.7 lb (1.22 kg). The bill
is long (about twice the length of the head), sharply pointed and
yellow as are the webbed feet.
Most
of the male Anhinga's body is a glossy black green with the wings,
base of wings, and tail being a glossy black blue. The tip of
the tail has white feathers. The back of the head and the neck
have elongated feathers that have been described as gray or
light purple white. The upper back of the body and wings is spotted
or streaked with white.
The
female Anhinga is similar to the male Anhinga except that it has
a pale gray-buff or light brown head, neck, and upper chest.
The lower chest or breast is a chestnut color and as compared to
the male, the female has a more brown back.
The
hatchling starts out bald but gains tan down within a few days of
hatching. Within two weeks the tan down has been replaced by white
down. Three weeks after hatching, the first juvenile feathers appear.
Juveniles are mostly brown until first breeding after the second
or third winter.
This
bird is often mistaken for a double-crested cormorant due to its
similar size and behavior. However, the two species can be differentiated
by their tails and bills. The tail of the anhinga is wider and much
longer than that of the cormorant. The bill of the anhinga is pointed,
while the bill of the cormorant has a hook-tip.
Conservation
status
The Anhinga is protected in the US under the Migratory Bird Treaty
Act of 1918. The number of individual anhingas have not been
estimated but they are considered to be of least concern because
of the frequency of their occurrence in their 15,000,000 km²
global range.
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