The Andaman Serpent Eagle, (Spilornis elgini), also known as the Andaman dark-serpent eagle or the dark serpent eagle, is a medium-sized bird in the family Accipitridae, the raptor family, that is only found in India on the Andaman Islands. It is currently classified as vulnerable and is experiencing population declines. This species, unlike Spilornis cheela, is incredibly understudied and so many things about its behaviour and ecology are still widely unknown.
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
Oviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
Altricial animals are those species whose newly hatched or born young are relatively immobile. They lack hair or down, are not able to obtain food ...
Soaring birds can maintain flight without wing flapping, using rising air currents. Many gliding birds are able to "lock" their extended wings by m...
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Not a migrantAnimals that do not make seasonal movements and stay in their native home ranges all year round are called not migrants or residents.
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starts withThe call of the Andaman serpent eagle consists of three to four short chip-sounding whistles. These birds are nearly entirely dark brown, except for their bright yellow faces and legs and they have spots on the tops of their wings and on their chests. They also have thick black bands on their tails and white and black bands on the underside of their wings. This species also has a hooked beak which is characteristic of a bird of prey and is used to tear apart food. Juvenile Andaman serpent eagles are known to have lighter colouring than adults and they also have a white head. Additionally, there is no sexual dimorphism between males and females, which means that it is impossible to differentiate the two sexes by physical characteristics alone.
The Andaman archipelago includes 204 islands, majority of which are forested, that all surround three main large islands. The Andaman serpent eagle has been found on all of the Andaman Islands, even on the islands with as little area as 0.8 km2, although they prefer larger ones, and have even been known to occupy two different islands at the same time. They are usually found inland in closed canopy evergreen forests, on hillsides and in tropical lowland areas, however they can also be found closer to the coast and on agricultural land. Additionally, this species uses mangrove marshes and creeks as nesting sites. Thus, they have some very specific habitat requirements that need to be met in order to successfully reproduce and these areas are currently being disturbed, which is threatening the species.
As their name suggests, the Andaman serpent eagle consumes snakes as well as other prey such as other birds, rats, frogs and other reptiles. In one study they were even observed to eat crabs and prawns that they could find on the ground. The serpent eagles are known to have thick scales on their legs and short toes and this is believed to help them prey on snakes while avoiding poisonous bites. The Andaman serpent eagle is known to hunt from perches, usually tree branches below the canopy. Once they spot prey from their elevated vantage point, they will swoop down to grab whatever it is they have spotted.
The serpent eagle genus has been known to perform elaborate aerial courtship routines. Aerial courtship displays are not the same for every species, however, for raptorial species, this means both birds will fly together and perform various movements and displays such as locking talons, rolling and diving.
In terms of population density, the Andaman serpent eagle is common within the archipelago it is endemic to, but its population size is actually quite small with fewer than 4000 individuals that are spread amongst various subpopulations. Individuals within this species tend to have a lifespan of 8 years.
The Andaman serpent eagle is currently considered vulnerable because it has a relatively small population in a limited habitat. Since the species is battling habitat degradation and encroachment from human movement to the larger islands, and logging, it is expected that their numbers will continue to decline over time. Conservation efforts are underway that consist of monitoring endemic bird species on the Andaman islands, additionally, education initiatives are being set up and essential habitat areas have been identified. Since this species has not been researched thoroughly, more in depth studies into behaviour and population numbers may be beneficial to inform on how best to conserve the species.
