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10 Amazing Facts About the Oriental Darter Bird

The Oriental Darter, or Anhinga melanogaster, is a stunning bird species found in many parts of the world. This bird is known for its unique features, which include a long, slender neck, a sharp bill, and a pointed tail.

While it may be easy to spot this bird due to its impressive appearance, there are some essential factors to fully understand this avian species. This article will explore the Oriental Darter, its identification, plumages, and molts.

Identification

Field Identification

The Oriental Darter is a medium-sized bird, usually measuring between 85-90 cm in length. It has a wingspan of approximately 115 cm long.

When in flight, the bird has a thin, snakelike head and neck that distinguishes it from other birds. Its beak is sharp and pointed to help it catch prey in shallow waters by spearing the prey, while the pointed tail helps maintain balance when perched on vegetation near water.

Similar Species

One of the Oriental Darter’s closest relatives is the American Anhinga or Anhinga anhinga, which shares some similarities in appearance. In North America, Double-crested Cormorants might appear similar when compared to Darters due to their slender necks, pointed beaks, and similar behaviors.

Plumages

The Oriental Darter has two distinctive plumages in its lifetime. The adult is known for its striking coloration, which boasts black feathers but with a white patch towards the base of its wings.

The head and neck are brown, while the rest of the bird’s body has a glossy black appearance. However, during the breeding season, the head and neck of the males transform to a luxurious mahogany coloration, while the females tend to stay brown.

Juveniles have brown pelage that fades away as they mature.

Molts

Birds go through molting at different times of the year. The Oriental Darter molts during the non-breeding season, which is usually from March to September.

During this time, the bird’s feathers become unusable and start to fall off, leading to its movements or behaviors being restricted to enable efficient feather shedding.

Conclusion:

The Oriental Darter is an interesting bird species with unique characteristics. Its stunning appearance, plumages, and molt make it a fascinating bird to watch.

With proper identification, bird watching enthusiasts all over the world can enjoy the beauty of the Oriental Darter.

Systematics History

The Oriental Darter, also known as Anhinga melanogaster, belongs to the genus Anhinga, which includes four other species widely spread throughout the Americas and Africa. This genus belongs to the family Anhingidae, famously known as darters or snakebirds.

The Anhingidae family comprises waterbirds that feed on fish and have elongated, snake-like necks. They are diurnal and largely solitary.

Geographic Variation

The Oriental Darter has geographic variation in coloration with birds from West Africa featuring paler underparts. The subspecies that occur around the Indian subcontinent and southeast Asia are darker than their African counterparts.

There is also variation in the number of breeding feathers found in the males between subspecies.

Subspecies

There are six subspecies of the Oriental Darter listed in the Handbook of the Birds of the World. They are:

1.

Anhinga melanogaster melanogaster – Occurs from Nepal, India through Myanmar to Thailand. 2.

Anhinga melanogaster rufa – Found in West Africa from Sierra Leone to Ghana. 3.

Anhinga melanogaster microsticta – Occurs in Southeast Asia from Indochina through to Sumatra. 4.

Anhinga melanogaster wangyongi – Found in China in the Sichuan basin region. 5.

Anhinga melanogaster pelewensis – Restricted to Palau in Micronesia. 6.

Anhinga melanogaster leucosticta – Occurs in Sulawesi, Maluku, and the Lesser Sundas in Indonesia.

Related Species

The Oriental Darter belongs to a family known as Anhingidae, consisting of four other species. The American Anhinga, Anhinga anhinga, is the most closely related species to the Oriental Darter and is found throughout South and Central America, as well as parts of North America.

The African Darter, or Anhinga rufa, is a related species mostly found in parts of Africa, while the Australian Darter, Anhinga novaehollandiae, and the New World Darter, Anhinga amazone, are found in Australia and South America, respectively.

Historical Changes to Distribution

The Oriental Darter occurs throughout much of tropical Asia and parts of West Africa. It is believed to have expanded its range in recent times, particularly in Africa, where it was not known before the mid-19th century.

It now breeds in West African countries, such as Gambia, Cameroon, Ghana, and Sierra Leone, where it was previously not recorded. In Southeast Asia, the Oriental Darter has an extensive distribution and has been known to breed in the region for many years.

However, there is some evidence to suggest that it has expanded its range northward in recent times. For instance, it has been recorded breeding in the Yangtze River basin in China, and its range extends northward to the Korean peninsula.

This expansion in range is thought to have been facilitated by a variety of factors, including changes in human land use and climate changes. Additionally, the Oriental Darter is a nomadic species and does not typically form large breeding colonies, so it is difficult to track the population accurately.

It is thought to be relatively common in much of its range, although habitat destruction and hunting pressure have led to some local reductions in population and range contraction.

Conclusion

The Oriental Darter, a waterbird belonging to the Anhingidae family, has six subspecies and a wide-ranging habitat throughout much of tropical Asia and parts of West Africa. The bird’s geographic variation, subspecies, and related species make for an interesting study.

The Oriental Darter has been recorded to have expanded its range in recent times, and this can be attributed to a variety of factors. However, more studies are needed to understand the bird’s migratory patterns and population accurately.

Habitat

The Oriental Darter is a freshwater bird species that is primarily found near shallow lakes, rivers, and swamps. These habitats provide the ideal grounds for the bird to forage for food and also build its nests.

Although the bird prefers freshwater habitats, it is occasionally found in brackish waters near mangroves, salt pans, and coastal lagoons. The species is non-migratory, and individuals tend to remain in the same area throughout the year.

The Oriental Darter is widely distributed across its range, but deforestation, conversion of land for agricultural use, and dam construction have led to the loss and degradation of its preferred wetland habitats. This has had a significant impact on the species, with some populations declining as much as 30% in the past 10 years.

Conservation efforts such as maintaining wetland habitats, regulating dam releases, and preserving forests in the vicinity of wetlands can help to mitigate the impacts of habitat loss.

Movements and Migration

The Oriental Darter is a non-migratory species and tends to remain in the same habitat throughout the year. However, the species is known to undertake some local movements, especially during the non-breeding season when it may move from areas with low fish availability to those with more abundant fish stocks.

In some cases, the Oriental Darter may move to other parts of its range during the non-breeding season. For instance, individuals breeding in Myanmar and northern Thailand may move southward to the Malay Peninsula during the non-breeding season and reside in coastal estuaries, where fish resources are abundant.

Despite being non-migratory, the Oriental Darter is regarded as a nomadic species and may abandon breeding sites if it perceives no suitable breeding conditions. During non-breeding times, the species may shift from one body of water to another within the same range.

The Oriental Darter is primarily a solitary animal, but may occur in loose groupings when foraging. During the breeding season, males may establish territories and attract mates through elaborate displays.

These displays involve the males stretching their necks, raising their wings, and gurgling in mid-air. When a female enters the territory, the male proceeds to swim in a zigzag motion while bobbing his head up and down.

Successful males will attract females, and the pair will build a nest in a tree or shrub overlooking water.

Conclusion

The Oriental Darter is a freshwater bird species found near shallow lakes, rivers, and swamps. Although a non-migratory species, local movements occur during the non-breeding season when the bird seeks areas with more abundant food resources.

Habitat loss, deforestation, and dam construction have had a significant impact on the species, with some populations declining significantly. Conservation of wetland habitats is crucial to mitigate the impacts of habitat loss, and management measures that preserve forested areas in the vicinity of wetlands are crucial to the species’ survival.

Diet and Foraging

Feeding

The Oriental Darter is a visually-oriented feeder, and it hunts beneath the surface of the water for its prey. The bird has a small number of breeding feathers, which allows it to dive deeper and stay under the water for longer periods.

Once it spots its prey, the bird spears it with its sharp bill. The Oriental Darter also uses its pointed tail to maintain balance when perched on vegetation near water.

Diet

The Oriental Darter feeds on a variety of fish species. Its preferred food is small minnows and fry, but it will also eat larger fish if they are available.

The bird’s diet varies by location, mainly dictated by the availability of food types. Its diet in the wetlands largely consists of fast-moving and small-bodied fish species, such as guppies and tetras.

As for variation, the subspecies Anhinga melanogaster microsticta has a confirmed diet of small-finned fishes, crayfish, aquatic insects, and crabs. In contrast, the Anhinga melanogaster melanogaster subspecies primarily feeds on carp, tilapia, and catfish.

Metabolism and Temperature Regulation

Since the Oriental Darter is an aquatic bird that spends most of its time in water, it relies on adjusting its metabolic rate to regulate body temperature, similar to other waterbirds. The bird has feathers that are not waterproof, meaning that they can become waterlogged, making it difficult for the bird to maintain its body heat.

The Oriental Darter, therefore, remains relatively inactive for long hours when not foraging to conserve energy. The Oriental Darter tends to spread its wings and tail when not foraging to dry them and protect itself from the sun’s heat.

It also pants like a dog while sitting at its perch, releasing heat to deal with the hot temperature.

Sounds and Vocal Behavior

Vocalization

The Oriental Darter has a variety of vocalizations that it uses for communication during the breeding and non-breeding periods. During breeding season, the male of this species vocalizes to attract and woo females, while the females drone their throats.

The bird can also produce vocalizations during courtship, which accompany the bird’s displays. Males also produce a grunting sound while preening themselves.

When communicating in groups, the Oriental Darter makes a variety of squawks, croaks, and yelps. Similarly, the bird may let out a series of quick, low grunts when disturbed.

Behavior

Locomotion

The Oriental Darter is an adept swimmer that uses its feet and wings for propulsion. The bird typically swims underwater to search for prey and has a very efficient hunting strategy, given its pointed beak and excellent vision.

When swimming, the bird’s bill acts as a spear, striking out at prey that come within range. The bird is known to swim long distances, and it can do so effortlessly.

The bird is also a skilled flyer and has a distinct flight pattern with its neck and head sticking out in front of its body.

Self-Maintenance

The Oriental Darter is an excellent self-maintainer and will engage in preening activities to maintain its feathers and keep them in pristine conditions. The bird also spreads its wings to dry them out after diving, sunbathe, and regulate its body temperature.

The Oriental Darter is also known to use its bill to remove parasites and other debris from its feathers and skin.

Agonistic Behavior

The Oriental Darter is a solitary bird that is generally non-aggressive. Males, however, may become territorial during the breeding season, with fights and aggressive displays occurring between competing males.

The males display their wings and necks and make gurgling sounds to attract females.

Sexual Behavior

Mating in Oriental Darters occurs during the dry season, and males attract females by making elaborate displays involving vigorous head movements, body postures, and vocalizations. Once a pair bonds, they will build a nest together.

The nests are made from a variety of materials such as twigs, leaves, and grasses, and commonly placed on branches overhanging water. Incubation usually lasts for 3-4 weeks, with both parents taking turns incubating the eggs.

Breeding

The Oriental Darter becomes sexually mature at around four years of age. The male selects a nest site and builds a platform that he will use to attract a mate.

After laying the eggs, the female incubates them for a duration of 21-25 days, during which time the male continues to provide food. Once the eggs hatch, the male and female care for the young and provide them with food in the form of fish.

The chicks are ready to fledge in around two months, after which time they leave the nest and become independent.

Demography and Populations

The Oriental Darter is not considered globally threatened, but some populations are declining rapidly in some areas.

Habitat destruction and pollution are the biggest threats to the species.

Due to their dependence on freshwater habitats, Oriental Darters are vulnerable to habitat loss, especially as their wetland habitats continue to be drained and used for rice farming, fishing, and urbanization. Conservation measures such as habitat restoration and the implementation of protections in key areas can go a long way in safeguarding this species’ survival.

However, there’s a lot to learn about Oriental Darter biology, with more studies needed in this field to create informed conservation plans for the species. The Oriental Darter is a fascinating bird species with unique characteristics, behaviors, and habitat preferences.

As a freshwater bird found near shallow lakes, rivers, and swamps, the Oriental Darter depends on pristine wetlands to survive. Despite its relatively non-aggressive nature, the bird is well-adapted for self-defense and capturing prey.

Though not globally threatened, local populations of Oriental Darters are declining rapidly, primarily due to habitat loss, pollution, and land-use changes. With the implementation of effective conservation measures aimed at habitat restoration and protection in key areas, the Orienta Darter’s survival can be guaranteed for many years to come.

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