Black Swan

Black swans are a beautiful and unique species of swan once believed to be nonexistent. It is the largest bird among all the waterfowl. Found in wetland areas, they are closely related to the mute swan.

The official state emblem of Western Australia is the black swan. While on the ground, a big group of these swans is called a bank, and in flight, the group is known as a wedge.

Description

Size: Length: 43-56 inches (110-142 cm); Weight: 8.2–19.8 lbs (3.7–9 kg).

Wingspan: 5.2 and 6.6 ft (1.6-2 m).

Body and Coloration: As suggested in the name, they are almost entirely black with white-tipped feathers on their wings. The white in their wings is only visible while in flight. Compared to other types of swans, these species have the longest necks. They have big feet, a red bill with a white band around it, and bright red eyes.

Although similar in appearance, males are mostly larger with slightly straighter bills and necks.

Cygnets have very different appearances than adults. They have a grey coloration and a bill that is almost black with a grey tip.  

Range and Distribution

These swans are mainly found in the southern part of Australia, including Tasmania, avoiding the northern tropics, especially the Cape York Peninsula. They are also distributed across Europe, New Zealand, and North America.

Habitat

Black swans mostly occupy tropical and temperate areas. They live in lakes, rivers, and swamps. Their preferred habitats are areas with aquatic vegetation. Although they are naturally of aquatic habitat, these swans can sometimes be found in terrestrial areas like a flooded field or dry pastures when the food supply is low.

Diet

Being herbivorous by nature, the primary diet of these swans includes algae, reedmace leaf, stoneworts, and other aquatic plants. Occasionally, they also consume insects.

Behavior

• Black swans are diurnal.
• They are the least territorial of all swans. 
• These birds move in flocks and nest in colonies.
• They fly together in a V shape line, slowly beating their wings and whistling.
• These swans have a range of calls, including soft crooning notes and bugle-like musical sounds, whistling, and trumpeting calls. They make whistle calls while defending the nests. Males’ trumpeting calls are deeper than females’.  
• While threatening, they stand holding their necks stretching out with ruffled feathers and the bill pointing downward and flap and wave their wings with 2-3 strokes, followed by a call. 
• They mostly swim in open waterways because they need over 20 feet to gain momentum before taking off.
• Black swans are highly nomadic. They do not have any migratory pattern, although they move around due to rainfall or drought. 
• They cannot fly for six weeks after breeding season due to molting. During this time, they gather in large numbers.

Lifespan

The lifespan of a black swan extends up to 40 years.

Adaptations

• While swimming, these birds tuck one of the legs above their tails, which helps them change direction easily and move quickly.
• Having 25 vertebrae in the neck allows them exceptional neck flexibility, allowing them to forage underwater without any need to dive.
• The fine grooves along their bills help them hold their food.

Mating and Reproduction

The breeding season lasts from February-May in the Northern Hemisphere and May-September in the Southern Hemisphere. Black swans are monogamous, staying in solitary pairs while mating; however, sometimes, they mate in colonies. During the mating ritual, the male approaches the female, lifting his wings and chin along with repeated calls. Once the female returns the same call, they dip their heads alternating with straight postures. They then outstretch their neck with bills pointing upward and start calling. After this, they hold their neck, angling 45⁰ with bills pointing downward, and start swimming in a circle.

The female lays 5-9 eggs, one day apart. Once all the eggs are laid, the incubation period starts. The female and the male both participate in the incubation process. The eggs hatch after 38-45 days.

Females make a nest that floats in water by piling up debris, dead leaves, and sticks. Although the cygnets are precocial, they are brooded in the nest for the first 2-3 weeks. They start fledging after 4-5 months (150-170 days). After about six months, these birds start flying but tend to stay close to the group. Black swans reach their reproductive maturity at 2-3 years of age.

Predators

Black swans do not have any natural predators. However, their eggs get taken by ravens, golden-bellied water rats, white-bellied sea eagles, swamp harriers, and other hawks. Newly fledging cygnets also become prey.

Conservation Status

The black swan is listed as “Least Concern” or “LC” by the IUCN in the Red List of Threatened species.

Some major threats to these birds are habitat loss, water pollution, and human interference.

Interesting Facts

• The first European to see the Australian black swans was a Dutch mariner named Antounie Caen in 1636 at Shark Bay.
• Nassim Nicholas Taleb, a Lebanese-American essayist, suggested the Black Swan Theory.  This theory refers to unexpected events that have a high impact and are improperly rationalized with the benefit of hindsight.