19.
Madagascar Serpent-eagle
(Eutriorchis astur)
EN
Overview
The Madagascar Serpent-eagle is one of the rarest birds of prey in the world. Endemic to Madagascar, its forest habitat is becoming increasingly depleted and fragmented. For many years it was doubted whether the species still survived in the wild, until it was recently rediscovered by Peregrine Fund biologists after six decades of absence. The use of playback techniques has demonstrated that the species is in fact not as rare as previously thought, resulting in it being downgraded from critically endangered to endangered. This is great news, however its population continues to decline as it suffers the devastating effects of rapid deforestation.
Urgent Conservation Actions
Research into population size and distribution, protection of areas where the species is recorded and improved conservation management of the east coast rainforest belt, where the species is known to exist.
Distribution
East Madagascar
Fact
Despite its name, the Madagascar Serpent-eagle mainly feeds on chameleons and geckos. Snakes make up only a tiny proportion of the bird’s diet.
Media from ARKive
Arkive image - Madagascar serpent-eagle juvenile at nest
Arkive image - Madagascar serpent-eagle nestling with adult male
Arkive image - Madagascar serpent-eagle fledgling in tree
Arkive image - Madagascar serpent-eagle fledgling in tree
Arkive image - Madagascar serpent-eagle female being held
Arkive image - Madagascar serpent-eagle male in habitat
Arkive image - Madagascar serpent-eagle in habitat
Arkive image - Madagascar serpent-eagle specimen
Evolutionary Distinctiveness
Order: Falconiformes (or Accipitriformes)
Family: Accipitridae
The Accipitridae is a diverse avian family, comprising of up to 14 subfamilies, 65 genera and 231 species. It comprises the hawks, eagles, ospreys and kites. It was previously suggested that Eutriorchis astur should be united in a genus with the Congo Serpent-eagle (Dryotriorchis) or that it was closely related to the genus Spilornis, containing other species of serpent eagle. However, recent DNA analyses indicate that the Madagascar Serpent Eagle may be more closely related to the three species of Old World vultures, which form the subfamily Gypaetinae.
The tree below shows the evolutionary relationships between this species and all other birds. The colours of the tree indicate EDGE scores with the red shades indicating the higher priority species; the bright red leaves correspond to the top 100 EDGE bird species. Further information on every species can be found by zooming in to its leaf on the tree.
Description
Size: 
66cm in length
Weight: 700g (males) – 800g (females)
This medium sized raptor has a dark brown head, black bill and yellow eyes. The plumage on its upperparts is pale brown, with very dark barring which is wider towards the wings and rump of the bird. The plumage on the underparts is white, with wide, brown barring. The long tail is pale brown with wide, dark brown bars. Its powerful legs are long and yellow. The juvenile has white edging to feathers on the head, back and wings.  The call of the Madagascar Serpent Eagle has been described as a loud wah…wah…wah, followed by a lower, almost frog-like, rugh.
Ecology
This diurnal predator hunts by swooping down from high perches and catching prey in its powerful talons. Chameleons and geckos are the prey animals of choice, with lemurs, lizards, frogs and snakes also being preyed upon. The name, Madagascar Serpent-eagle, is somewhat misleading as snakes make up only a tiny proportion of the bird’s diet. Little can be concluded about the species’ breeding habits as only two nests have been thoroughly monitored. Observations of these nests suggest that one egg is laid, which both parents (although mostly the female) incubate over a period of 40 days. The chick fledges after 58-62 days. Pairs nest only once every one to two years and as such productivity is very low.
Habitat
The Madagascar Serpent-eagle can be found in lowland and mid-altitude primary rainforest up to 1,000m above sea level. Predominantly a forest-dweller, it rarely ventures beyond the forest edge.
Distribution
This rare raptor inhabits mainly primary rainforest in East Madagascar.
Population Estimate
250-999 mature individuals
Population Trend
Declining
Status
Endangered
Threats
The main concern for this endemic eagle is deforestation. Over the last 2,000 years over 90% of Madagascar’s native forest has disappeared due to subsistence slash and burn agriculture and, more recently, commercially logging. The pristine lowland forest the Madagascar Serpent-eagle relies upon continues to be destroyed at a rapid rate, making these forests some of the most threatened on the planet. Other threats include uncontrolled bush fires and poor mining practices.

As the forest becomes more fragmented eagles come into closer proximity to human communities and although there is little solid evidence to back up such a claim, farmers have been known to persecute the eagles believing they prey upon their chickens. Local people may however be confusing the eagle with Henst’s Goshawk, a similar-looking species known to take chickens.
Conservation Underway
This species is protected under CITES Appendix II. The species occurs in several protected forest areas: four National Parks, two Special Reserves, one Strict Reserve and one Classified Forest. It is also found in ten of the 30 Important Bird Areas (IBAs) in eastern Madagascar. The Peregrine Fund supports an ongoing research programme into the species’ behaviour and ecology. In 2003, a pioneering government plan began to triple Madagascar’s protected areas to almost 60,000 square kilometres. These new protected areas include some of the country’s most pristine forests, including the Makira corridor which has much of the remaining lush lowland forest that is home to the major population of the Madagascar Serpent-eagle.
Conservation Proposed
Further surveys are necessary to ascertain whether this species survives in the southern half of the eastern rainforest belt, including Ranomafana and Midongy-South National Parks. Determining more refined population estimates as well as improved management and conservation measures of the east coast rainforest belt would aid the species’ recovery. A number of organisations are assisting the government with its protected area programme, including Conservation International, the Wildlife Conservation Society, World Wildlife Fund and the World Bank. The next phase of the programme aims to bolster economic efforts for the thousands of local people living in and around the protected areas through ecotourism, ecosystem services contracts and ecological monitoring initiatives.
Links
References
BirdLife International (2012). Eutriorchis astur. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. www.iucnredlist.org. Downloaded on 30 January 2013.

BirdLife International (2013) Species factsheet: Eutriorchis astur. Downloaded from www.birdlife.org on 30/01/2013.

Ferguson-Lees, J. & Christie, D.A. (2001) Raptors of the world. Christopher Helm: London. pp. 992

Langrand, O. (1990). Guide to the birds of Madagascar. Yale University Press, New Haven, USA.

Lerner, H. R. L. & Mindell, D. P. 2005. Phylogeny of eagles, Old World vultures, and other Accipitridae based on nuclear and mitochondrial DNA. Molecular Phylogenetics and Evolution 37: 327-346.

Thorstrom, R.; Watson, R. T. (1997). Avian inventory and key species of the Masoala Peninsula, Madagascar. Bird Conservation International 7: 99-115.

Thorstrom, R.; René de Roland, L.-A. (2000) First nest description, breeding behaviour and distribution of the Madagascar Serpent-Eagle Eutriorchis astur. Ibis 142: 217-224.
Acknowledgements
Text compiled by Michelle Harrison.

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