Black Swan (Cygnus atratus) – Planet of Birds

Black Swan

Subspecies

Genus	Species	subspecies	Region	Range
Cygnus	atratus		AU	Australia, New Zealand

Genus

Swans, genus Cygnus, are birds of the family Anatidae, which also includes geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae where they form the tribe Cygnini. Sometimes, they are considered a distinct subfamily, Cygninae. There are six to seven species of swan in the genus Cygnus; in addition there is another species known as the Coscoroba Swan, although this species is no longer considered related to the true swans. All evidence suggests that the genus Cygnus evolved in Europe or western Eurasia during the Miocene, spreading all over the Northern Hemisphere until the Pliocene. When the southern species branched off is not known. The Mute Swan apparently is closest to the Southern Hemisphere Cygnus (del Hoyo et al., eds, Handbook of the Birds of the World); its habits of carrying the neck curved (not straight) and the wings fluffed (not flush) as well as its bill color and knob indicate that its closest living relative is actually the Black Swan. Given the biogeography and appearance of the subgenus Olor it seems likely that these are of a more recent origin, as evidence shows by their modern ranges (which were mostly uninhabitable during the last ice age) and great similarity between the taxa.

Physical charateristics

In adult Black Swans the body is mostly black, with the exception of the broad white wing tips which are visible in flight. The bill is a deep orange-red, paler at the tip, with a distinct narrow white band towards the end. Younger birds are much greyer in colour, and have black wing tips. Adult females are smaller than the males.

Listen to the sound of Black Swan

[audio:http://www.planetofbirds.com/MASTER/ANSERIFORMES/Anatidae/sounds/Black Swan.mp3]

Copyright remark: Most sounds derived from xeno-canto

wingspan min.:	160	cm	wingspan max.:	180	cm
size min.:	110	cm	size max.:	120	cm
incubation min.:	35	days	incubation max.:	48	days
fledging min.:	60	days	fledging max.:	48	days
broods:	1		eggs min.:	4
			eggs max.:	7

Range

Australasia : Australia, New Zealand

Habitat

Black Swans prefer larger salt, brackish or fresh waterways and permanent wetlands, requiring 40 m or more of clear water to take off. Outside the breeding season, Black Swans travel quite large distances. Birds fly at night and rest during the day with other swans.

Reproduction

Black swans are monogamous and often have the same mate for life. They are territorial and stay in solitary pairs when mating but are known to occasionally mate in colonies. The threatening behavior of black swans is similar to mute swans; they both flap and wave their wings with two or three strokes followed by a call. However, the wings of black swans make a louder sound than mute swans. Also the standing stance is different; black swans hold their necks erect with a downward point of the bill and ruffled feathers.

One particularly interesting thing about the courting behavior of black swans is the “Triumph Ceremony”. It is used to strengthen pair-bonds between mates, between parents and cygnets (baby swans), and for threatening territorial displays. The male swan approaches the female swan with wings and chin lifted, calling repeatedly. Then the female returns the same call. They then dip their heads alternating with erect postures. After this the birds call with their necks outstretched and bills pointed upward; then they hold their necks at a forty five degree angle and point their bills downward and at a right angle, they proceed to swim in a circle. These ceremonies are primarily initated by the male and tend to increase in frequency when there are more swans around.

The breeding season is from February through September. Usually the female (occasionally the male) makes a nest of sticks, dead leaves and debris into a floating mound on top of the water. Each female may lay between 5 to 6 eggs, the eggs are laid one day apart. There is a 35 to 48 day incubation period which begins when all the eggs have been laid. Males are known to help with incubation. Chicks are precocial and fledge soon after hatching. They remain in family groups for about 9 months. The chicks are sexually mature in 18 to 36 months. Young black swans join juvenile flocks for one to two years before they begin breeding.

Both male and female black swans incubate the eggs. Chicks are precocial and can swim and feed soon after hatching. They may ride on their parents’ backs when they venture into deep water. The chicks can fly in 2 months, but they remain in the family group until the next breeding season. Juvenile black swans often form flocks until they find a mate.

Feeding habits

Cygnus atratus eats sub-aquatic foliage that it can reach under water using its long neck. It is herbivorous, eating vegetation and plants either in the water or on land in pastures or on farm land. Occasionally they also eat insects.

Video Black Swan

httpv://www.youtube.com/watch?v=ygEhZm8Q-58

Conservation

This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Cygnus atratus, commonly known as black swans, are native to Australia and Tasmania but have been introduced to New Zealand and Europe. Black swans are found mainly in the wetlands of Southern Australia and tend to avoid the northern tropics. They can also be found in southeast Australia to southwest Australia and in the southeast of Tasmania. After being introduced to Europe as pets, they can now be found there in the wild.
Black Swans are found throughout Australia with the exception of Cape York Peninsula, and are more common in the south. The Black Swan has been introduced into several countries, including New Zealand, where it is now common, and is a vagrant to New Guinea.

Migration

Sedentary in permanent suitable habitat; young and adults from ephemeral waters wander extensively; erratic observations outside normal range frequent. Vagrant to New Guinea. . Introduced resident species in Europe.

Distribution map

Black Swan distribution range map

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