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Réunion Marsh Harrier
Circus maillardi

Status: Endangered

Population Trend: Increasing.

Other Names: Réunion Marsh-harrier.

Circus maillardi
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Distribution: Afrotropical. Endemic to RÉUNION ISLAND.

Subspecies: Monotypic.

Taxonomy: Formerly merged with C. macrosceles and even C. aeruginosus (Sibley and Monroe 1990), but treated as a separate species by Bretagnolle et al. (2000) and Simmons (2000), based on differences in morphology and plumage. Wink and Sauer-Gürth (2004) confirmed that C. aeruginosus, C. ranivorus, C. spilonotus, C. approximans, C. macrosceles, and this species form a monophyletic group, based on evidence from the mitochondrial cytochrome b gene.

Movements: Non-migratory (Bildstein 2006).

Habitat and Habits: Occurs in a wide variety of habitats, shunning only urban and suburban areas. Most common in marshy areas, but forages mostly on dry mountainsides and in forest patches, much more so than the related Madagascar Harrier or any other harrier. Nests in forests from sea level to 1,200 m and possibly 1,600-1,800 m; most pairs are concentrated between 300-700 m (Bretagnolle et al. 2000).

Food and Feeding Behavior: Feeds on small vertebrates, including birds, insects, rats, mice, and tenrec (Clouet 1978), which it captures while coursing low over wet vegetation, or by soaring over forest and descending into the canopy.

Breeding: The nest is placed on the ground in a marshy area.

Conservation: The total population is very small and was estimated at only 50-100 pairs by Bretagnolle et al. (2000), who surveyed a portion of the island in 1997-1998 and extrapolated to a likely populaton size based on available habitat. This estimate is considerably lower than the earlier estimates of 200 pairs by Clouet (1978) and 300 pairs (Barre et al. 1996). Bretagnolle et al. (op cit.) found no evidence that the species was declining, so they recommended treating it as Vulnerable. BirdLife International classifies this species as Endangered, based mainly on its small population size and small range. They cited another recent report that there may be as many as 130-170 pairs remaining (M. Le Corre in litt.), and they presently regard the population as increasing.
The principal threats to this species appear to be shooting and habitat loss, as a result of increasing urbanization and expanding agriculture.

Important References: 
Barre, N., A. Barau, and C. Jouanin. 1996. Oiseaux de la Réunion. Editions
  du Pacifique, Paris.
BirdLife International. 2007. Species factsheet: Circus maillardi.
Bretagnolle, V., T. Ghestemme, J.-M. Thiollay, and C. Attié. 2000.
  Distribution, population size and habitat use of Réunion Marsh Harrier,
  Circus m. maillardi. Journal of Raptor Research 34:8-17.
Bretagnolle, V., J.-M. Thiollay, and C. Attíe. 2000. Status of Réunion
  Marsh Harrier Circus maillardi on Réunion Island. Pp. 669-676 in R.D.
  Chancellor and B.-U. Meyburg (eds.), Raptors at risk. World Working Group on
  Birds of Prey, Berlin, and Hancock House, Blaine, WA.
Cheke, A.S. 1987. The ecology of the surviving native land birds of
  Réunion. Pp. 301-358 in A.W. Diamond (ed.), Studies of Mascarene Island
  birds. Cambridge University Press, Cambridge, UK.
Clouet, M. 1978. Le Busard de Maillard, Circus aeruginosus maillardi, de
  l'Isle de Réunion. Oiseau et la Revue Française d'Ornithologie 48:95-106.
Collar, N.J., and S.N. Stuart. 1985. Threatened birds of Africa and
  related islands: the ICBP/IUCN Red Data Book. Part I. 3rd ed. International
  Council for Bird Preservation and International Union for Conservation of
  Nature and Natural Resources, Cambridge, UK.
Ferguson-Lees, J., and D.A. Christie. 2001. Raptors of the world. Houghton
  Mifflin, Boston, MA.
Jones, C.G. 1989. Aerial display of the Réunion Harrier. Gabar 4:22-23.
Kemp, A.C. 1994. Madagascar Marsh-harrier. P. 138 in del Hoyo, J., A.
  Elliott, and J. Sargatal (eds). Handbook of birds of the world. Vol. 2. New
  World vultures to guineafowl. Lynx Edicions, Barcelona, Spain.
Louette, M. 2001. Adaptation of Comoro birds to disturbed forest habitat.
  Ostrich Supplement 15:48-55.
Simmons, R. 2000. Harriers of the world: their behaviour and ecology.
  Oxford University Press, Oxford, UK.
Wink, M., and H. Sauer-Gürth. 2000. Advances in molecular systematics of
  African raptors. Pp. 135-147 in R.D. Chancellor and B.-U. Meyburg (eds.),
  Raptors at risk. World Working Group on Birds of Prey, Berlin, and Hancock
  House, Surrey, British Columbia, Canada.

Scott, Don

Last modified: 2/17/2011

Recommended Citation: Global Raptor Information Network. 2020. Species account: Réunion Marsh Harrier Circus maillardi. Downloaded from http://www.globalraptors.org on 12 Jul. 2020

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