Bird O'clock

Discovering the Andaman Serpent-Eagle: An Endangered Species on the Brink

The Andaman Serpent-Eagle, also known as Spilornis elgini, is a bird of prey found in the Andaman Islands of India. It is a relatively small eagle, measuring around 55-66 cm in length with a wingspan of 130-161 cm.

Its scientific name is dedicated to the Scottish ornithologist, William Alexander Elgin, who discovered this species in the Andaman Islands.

Identification

Field

Identification: The Andaman Serpent-Eagle can easily be recognized by its size and features. It has a pale head and throat, and a dark grey-black upper part of the body.

Its underparts are lighter in color, with prominent blackish streaks that help in distinguishing it from other bird species in the area. Its legs are yellow, and the feet and talons are black.

Similar Species: This species can be easily confused with the Crested Serpent-Eagle, which is similar in size and shape. However, the Andaman Serpent-Eagle has less white on its head, and more black streaking on its underparts.

The plumage coloration of the Andaman Serpent-Eagle is also darker than that of the Crested Serpent-Eagle.

Plumages

The Andaman Serpent-Eagle has two different plumages:

Adult Plumage: The adult has a dark bluish-gray back and wings with a pale head and neck. Its underparts have a distinct blackish-brown streaked pattern.

The eyes are a light yellow and the beak is dark grey or black. The bird also has a crest of feathers on its head.

Juvenile Plumage: Juvenile Andaman Serpent-Eagles have brown feathers on their wings and back, with white streaks. Their faces and underparts have a paler color than the adults, and there is no crest of feathers on their heads.

Molts

The Andaman Serpent-Eagle undergoes two molts per year, where it sheds old feathers and replaces them with new, fresh ones. These molts occur in the summer and winter seasons.

In conclusion, the Andaman Serpent-Eagle is a bird of prey that is unique to the Andaman Islands of India. It is distinct in its appearance, with a pale head, dark grey-black upper body and yellow legs.

It is important for bird enthusiasts and environmentalists to spot, identify and preserve this bird species for future generations.

Systematics History

The systematics history of any organism refers to its classification based on its relationships to other organisms through its evolutionary history. The Andaman Serpent-Eagle, also known as Spilornis elgini, is a bird from the Accipitridae family.

The first recorded sighting of the bird was in 1864 by the Scottish ornithologist, William Alexander Elgin, who discovered it in the Andaman Islands of India.

Geographic Variation

Geographic variation is the study of the differences in subpopulations or races of a species that occupy different geographical areas. The Andaman Serpent-Eagle shows little to no geographic variation as it is restricted to the Andaman Islands.

However, there are slight variations within the Andaman Islands itself, which are recognized as different subspecies.

Subspecies

Subspecies are subdivisions of a species that differ from other subspecies in certain physical or genetic characteristics. The Andaman Serpent-Eagle has two recognized subspecies:

– Spilornis elgini elgini: This subspecies is found in the southern Andaman Islands and is larger than the other subspecies.

Its coloration is slightly darker with broader streaking on the underparts. – Spilornis elgini hoya: This subspecies is found in the northern Andaman Islands and is smaller than the other subspecies.

Its coloration is slightly lighter with narrower streaking on the underparts.

Related Species

The Andaman Serpent-Eagle has several related species within the Spilornis genus. These include:

– Crested Serpent-Eagle (Spilornis cheela): This species is similar in size and shape to the Andaman Serpent-Eagle.

It is distributed throughout South and Southeast Asia, but not in the Andaman Islands. – Nicobar Serpent-Eagle (Spilornis klossi): This species is found only in the Nicobar Islands of India and belongs to the same Spilornis genus.

It is similar in appearance to the Andaman Serpent-Eagle but is slightly smaller in size.

Historical Changes to Distribution

Historical changes to distribution refer to the past changes in the distribution of a species due to several reasons such as climate change or human intervention. The Andaman Serpent-Eagle was first described in 1872, and its distribution has remained restricted to the Andaman Islands ever since.

However, there were several historical events that had an impact on its distribution. During the last glacial period, which was about 20,000 years ago, the sea level was lower, and the Andaman Islands were part of a land bridge that connected the Asian mainland to Sumatra.

This land bridge allowed the Andaman Serpent-Eagle to migrate and occupy the Andaman Islands, where it has remained to this day. In the past, several political interventions have had an impact on the distribution of the Andaman Serpent-Eagle.

During World War II, the Andaman Islands were under Japanese occupation, which led to forest destruction and hunting of wildlife. This had an adverse effect on the population of the Andaman Serpent-Eagle, reducing its numbers drastically.

Conclusion

In conclusion, the Andaman Serpent-Eagle is a unique bird species that is restricted to the Andaman Islands of India. The bird shows little to no geographic variation, but there are slight variations within the Andaman Islands themselves that are recognized as subspecies.

The Andaman Serpent-Eagle is related to other species within the Spilornis genus, such as the Crested Serpent-Eagle and the Nicobar Serpent-Eagle. Historical changes in distribution, such as climate change and human intervention, have had an impact on the species.

Habitat

The Andaman Serpent-Eagle is found exclusively within the forests of the Andaman Islands in India. They are known to inhabit a variety of forest types, including evergreen, deciduous, and mangrove forests.

The bird also occupies secondary forests and forest edges at elevations ranging from sea level up to 1200 meters. The Andaman Serpent-Eagle is known to prefer undisturbed forested areas with large trees for nesting.

They can also be observed near waterways, such as rivers or streams, where they hunt for prey. The bird is capable of adapting to human-modified habitats, including plantations and areas near human settlements.

However, their population is dependent on the availability of undisturbed forest habitats.

Movements and Migration

The Andaman Serpent-Eagle is considered a sedentary species, with little evidence of long-distance movements or migration. However, there is some evidence that birds on smaller islands within the Andaman archipelago may make short-distance seasonal movements to find food resources.

The breeding season for the Andaman Serpent-Eagle is between January and June, with young birds fledging from July to November. During the breeding season, the birds are typically territorial, defending their nest sites and surrounding areas from intruders.

However, outside of the breeding season, there is evidence that the birds may form small groups or roost in communal tree perches. The Andaman Serpent-Eagle is known to engage in a range of flight behaviors, including soaring, gliding, and flapping, to hunt for prey.

They are also known to use thermals and updrafts to stay aloft, minimizing their energy expenditure while flying.

Conservation

The Andaman Serpent-Eagle is classified as a vulnerable species on the IUCN Red List due to habitat loss caused by human activities such as deforestation, mining, and agriculture. The bird is also hunted for food and medicinal purposes, further contributing to its declining population.

The Andaman Serpent-Eagle is protected under Indian wildlife laws, and several conservation programs have been initiated to protect the bird’s habitats and populations. Measures such as establishing protected areas, habitat restoration, and public awareness campaigns have been undertaken to conserve the species.

Conclusion

In conclusion, the Andaman Serpent-Eagle is a sedentary species found exclusively within the forests of the Andaman Islands in India. The habitat requirement of the bird is undisturbed forests with large trees where they can nest and hunt for prey.

While there is little evidence of long-distance movements or migration, some birds on smaller islands within the Andaman archipelago may engage in seasonal movements. The declining population of the Andaman Serpent-Eagle is largely due to habitat loss and hunting.

Conservation measures such as habitat protection and public awareness campaigns are essential for the survival of the species.

Diet and Foraging

The Andaman Serpent-Eagle is a bird of prey that primarily feeds on snakes and lizards, although it also feeds on small mammals, birds, and insects. The bird is known to hunt by perching on a high vantage point, such as a tree, and scanning the surrounding area for prey.

Once the prey is spotted, the bird swoops down to catch it. The bird is also capable of hovering while hunting its prey.

Feeding

The Andaman Serpent-Eagle tears large prey into small pieces and eats it while perched on a tree. It does not fly while eating.

It occasionally stores food in a tree before consumption.

Diet

The Andaman Serpent-Eagle is a specialist predator of snakes and lizards. They have been observed hunting several species of snakes, including vipers and cobras, by attacking them on the ground or tree branches.

In addition to snakes and lizards, the bird also feeds on small mammals such as rats, shrews, and bats, and birds such as doves and pigeons. The bird will also feed on insects, scorpions, and crabs if prey availability is low.

Metabolism and Temperature Regulation

Like all birds, the Andaman Serpent-Eagle has a high metabolic rate and requires a constant supply of food to survive. Birds are endothermic animals, which means they can maintain their body temperature independently of the environment.

The Andaman Serpent-Eagle has unique adaptations in its body to regulate its internal temperature. For example, the bird has a high density of feathers that insulate its body and help to retain heat.

In contrast, when the bird needs to cool down, it spreads its feathers to allow air to circulate and evaporate sweat from its skin.

Sounds and Vocal Behavior

Vocalization

The Andaman Serpent-Eagle is a bird of prey that emits several types of vocalizations to communicate with its mate or during territorial displays. The bird’s vocalizations include calls, screams, whistles, and whines.

The female bird emits a higher-pitched call compared to the male. The birds primarily vocalize during the breeding season.

The song of the Andaman Serpent-Eagle is a series of loud, rising whistles. During territorial displays, the male and female birds may engage in duets, where they call in response to each other’s vocalizations.

These duets help the birds to establish and defend their territories against intruders.

Conclusion

In conclusion, the Andaman Serpent-Eagle is a bird of prey that primarily feeds on snakes and lizards. The bird is capable of hovering while hunting and tears its prey into small pieces before consumption.

The Andaman Serpent-Eagle has unique adaptations in its body to regulate its internal temperature. The bird communicates through vocalizations, including songs and duets, to establish territories and attract mates.

Conservation efforts such as climate change adaptation should be undertaken to ensure that the bird does not go extinct.

Behavior

Locomotion

The Andaman Serpent-Eagle is a bird of prey that has adapted to living in forested areas, relatively inaccessible to humans. The bird uses its wings and feet to navigate through the dense vegetation, tree branches, and soil.

While perching, the bird spreads both its wings to maintain balance and stabilize its position. During flight, the bird flaps its wings vigorously to take off and maintain its flight.

Self Maintenance

The Andaman Serpent-Eagle is known to bathe and preen its feathers to remove dirt and maintain their feathers’ health. They also sharpen their talons and beak to keep them in top condition for hunting.

Agonistic Behavior

The Andaman Serpent-Eagle is known for its aggressive behavior towards other birds that invade its territory. Adults show an active defense of their nests and young, driving away or attacking intruders, including other bird species.

Agonistic behavior shows when the bird engages in territorial displays, such as calling and duetting with other members of its species.

Sexual Behavior

The Andaman Serpent-Eagle is known for its monogamous mating system, where each male and female bird establish a pair-bond that lasts throughout the breeding season. Courtship behavior is common during the mating season, where the male and female engage in vocalizations and physical displays to attract each other.

Breeding

The breeding season for the Andaman Serpent-Eagle is between January and June. The male bird usually initiates the breeding process by displaying courtship behavior to a female bird.

During courtship, the male will present food to the female bird, which is a sign of his ability to catch prey and provide for her and their offspring. Once the pair has established a bond, they will locate a suitable nest site in a tall tree with good visibility of the surrounding landscape.

The male and female bird will work together to build a nest of sticks and twigs, which is lined with leaves and soft materials such as animal fur or moss. The nest may be placed between 10 to 60 meters high in a tree.

Both parents will incubate the eggs for around 35 days, with the female bird carrying out most of the incubation. After hatching, the young birds remain in the nest for around 60-70 days before fledging.

The young birds are fed by both parents, who regurgitate food for them. Once the young birds leave the nest, they will remain with their parents for several weeks until they are capable of catching their own prey.

Demography and Populations

The Andaman Serpent-Eagle is a vulnerable species, with a small and fragmented population restricted to the Andaman Islands.

Habitat destruction, hunting, and trapping have all had a damaging effect on the population.

However, conservation efforts such as habitat restoration and public awareness campaigns have been initiated to protect the species. The bird also faces threats from climate change, which may change the bird’s habitat and affect its ability to find food.

Sea-level rise could increase the area of saline water in the Andaman Islands, and an increase in temperature and humidity could also lead to changes in the bird’s ecology. Monitoring the population size and breeding success of the Andaman Serpent-Eagle is essential for its conservation.

Researchers have used techniques such as nest surveys, radio tracking, and satellite telemetry to monitor the bird’s population distribution, movement, and survival.

Conclusion

In conclusion, the Andaman Serpent-Eagle is a monogamous bird that establishes a pair-bond to breed and raise its young. The bird is territorial, and the adults actively defend their nests and young against intruders.

Human activities such as deforestation, hunting, and trapping are significant threats to the population of Andaman Serpent-Eagle, and measures such as habitat restoration and public awareness campaigns are essential for its conservation. The bird also faces threats from climate change, which makes monitoring the population size and breeding success of the species all the more critical.

In conclusion, the Andaman Serpent-Eagle is a unique bird species that exists exclusively in the Andaman Islands of India. Through this article, we have learned that the bird is identifiable by its size, color, and habitat.

We also explored the bird’s behavior, including its locomotion, self-maintenance, agonistic, and sexual behavior, and breeding. The Andaman Serpent-Eagle primarily feeds on snakes and lizards and is vulnerable to habitat loss, hunting, trapping, and climate change.

The bird is a valuable part of the biodiversity of the Andaman Islands, and it is important that significant efforts continue to be made to preserve and conserve its population and habitat.

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