Madagascar fish-eagle  (Haliaeetus vociferoides)

Madagascar fish-eagle

Facts

Kingdom Animalia
Phylum Chordata
Class Aves
Order Falconiformes
Family Accipitridae
Genus Haliaeetus (1)
Weight Male 2.2 - 2.6 kg (2)(3)
Female 2.8 - 3.5 kg (2)(3)

Status

Classified as Critically Endangered (CR - C2b) on the IUCN Red List 2002 (4), and listed on Appendix II of CITES (5).

Description

This large bird is one of the rarest birds of prey (6) and is the largest raptor in Madagascar (7). The body is a dark reddish-brown colour apart from the whitish cheeks and throat and white tail (8). The Madagascar fish-eagle has a melodious call, similar to the closely related African fish-eagle (Haliaeetus vocifer) (8).

Range

Endemic to Madagascar, the fish-eagle ranges along the west coast from Morombe in the southwest to Diego Suarez in the north (9). The population comprises at least 222 individuals (adults and juveniles) and includes 63 known breeding pairs (9). The population is fragmented into at least two sub-populations; one occupying the northwest coastal region and the other in the inland Antsalova region of west-central Madagascar (9).

Habitat

Madagascar fish-eagles occupy estuaries, mangroves and marine islands in the northwest, and inland freshwater rivers and lakes in the Antsalova region (9). They require large trees and/or cliffs close to water for nesting and foraging (10).

Biology

The breeding season runs from May to October (11). Maximum clutch size is two, but only one chick per nest survives due to siblicide (11). 35% of the known breeding population exhibits cooperative breeding strategies (3). The most common cooperative strategy is known as 'polyandry', when a female mates with more than one male (2).

The Madagascar fish-eagle is a fish specialist (12) and catches its prey by snatching fish from the water’s surface rather than by plunge diving (2).

Threats

It has been widely accepted that the Madagascar fish-eagle suffered a drastic population decline during the mid-20th Century (4), although recent genetic research suggests that the population has always been naturally small (3). However, the species’ small population size and fragmented distribution still leaves it vulnerable to extinction risks. Potential threats to the species’ survival include habitat degredation and direct and indirect human persecution (9). Additionally, the effects of behavioural traits such as poor juvenile dispersal (13) and incestuous matings (2) (14) may lead to problems of inbreeding depression (3).

Conservation

The Madagascar fish-eagle is protected by its listing on Appendix II of the Convention on International Trade in Endangered Species (CITES) (5). In 1998, Madagascar became a signatory to the International Ramsar Convention on Wetlands, and a complex of four lakes in the Antsalova region were designated as a site of Wetlands of International Importance (15). These sites (known as the Manambolomaty Complex) support 10% of the world population of Madagascar fish-eagles (9). In addition, the Peregrine Fund has initiated a Madagascar Fish Eagle Conservation Programme (16), enabling detailed studies of this species as well as the initiation of a sustainability project for the local people who share their natural resources with the fish-eagles.

Further Information

For more information on the Madagascar fish eagle see:

Authentication

Authenticated (19/9/2003) by Ruth Tingay, University of Nottingham/ The Peregrine Fund.
www.geog.nottingham.ac.uk/newgeog/profiles/researchstudents/tingay-ruth.htm

Glossary

Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
Inbreeding depression: the reduction in viability, birth weight, and fertility that occurs in a population after one or more generations of inbreeding (interbreeding amongst close relatives).
Raptor: bird of prey. Raptors are members of the taxonomic order Falconiformes.
Siblicide: the killing of siblings.

References

  1. del Hoyo, J., Elliott, A. and Sargatal, J. (1994) Handbook of the Birds of the World: New World Vultures to Guineafowl. Volume 2. Lynx Edicions, Barcelona.
  2. Tingay, R.E. (2000) Sex, lies and dominance: paternity and behaviour of extra-pair Madagascar Fish Eagles. MSc Thesis, University of Nottingham.
  3. Tingay, R.E. (in prep 2003). Population dynamics and behavioural ecology of the Madagascar Fish Eagle: Implications for conservation. PhD Thesis, University of Nottingham.
  4. IUCN Red List (August, 2003)
    www.redlist.org
  5. CITES (August, 2003)
    www.cites.org
  6. Meyburg, B.-U. (1986) Threatened and near-threatened diurnal birds of prey of the world. Birds of Prey Bulletin 3: 1 - 12.
  7. Langrand, O. (1990) Guide to the Birds of Madagascar. Yale University Press.
  8. Seibold, I. and Helbig, A.J. (1996) Phylogenetic relationships of the sea eagles (genus Haliaeetus): reconstructions based on morphology, allozymes and mitochondrial DNA sequences. Journal of Zoology, Systematics and Evolutionary Research, 34: 103 - 112.
  9. Rabarisoa, R., Watson, R.T., Thorstrom, R. and Berkelman, J. (1997) Status of the Madagascar Fish Eagle Haliaeetus vociferoides in 1995. Ostrich, 68 (1): 8 - 12.
  10. Berkelman, J., Fraser, J.D. and Watson, R.T. (2002) Nesting and perching habitat use of the Madagascar Fish Eagle. Journal of Raptor Research, 36 (4): 287 - 293.
  11. Watson, R.T., Razafindramanana, S., Thorstrom, R. and Rafanomezantsoa, S. (1999) Breeding biology, extra-pair birds, productivity, siblicide and conservation of the Madagascar Fish Eagle. Ostrich, 70 (2): 105 - 111.
  12. Berkelman, J., Fraser, J.D. and Watson, R.T. (1999) Madagascar Fish Eagle prey preference and foraging success. Wilson Bulletin, 111: 15 - 21.
  13. Rafanomezantsoa, S., Watson, R.T. and Thorstrom, R. (2002) Juvenile dispersal of Madagascar Fish Eagles tracked by satellite telemetry. Journal of Raptor Research, 36 (4): 309 - 314.
  14. Tingay, R.E., Culver, M., Hallerman, E.M., Watson, R.T. and Fraser, J.D. (2002) Subordinate males sire offspring in Madagascar Fish Eagle (Haliaeetus vociferoides) polyandrous breeding groups. Journal of Raptor Research, 36 (4): 280 - 286.
  15. Ramsar Convention (August, 2003)
    www.ramsar.org
  16. The Peregrine Fund (August, 2003)
    www.peregrinefund.org