- Circus maillardi
- Black head
- Black mantle, upperwing coverts and outer primaries, rest of upperwing pale grey with some black spots
- Neck and throat area white with black streaks
- Underside white with white wing coverts and black outer primaries; rest of primaries and secondaries with two dark bars
- The tail is grey with dark subterminal band
- the rump is white
- Dark brown upperside
- White rump with a brown wash and barred tail
- Underwing has brownish coverts, heavily barred flight feathers and dark tipped primaries
- Underside of body is pale with brown streaks more prominent on throat and breast
Marshland and grassland
Diet includes rats, mice and insects.
2-3 white eggs are laid.
- Clements, JF. 2009. The Clements Checklist of Birds of the World. 6th ed., with updates to December 2009. Ithaca: Cornell Univ. Press. ISBN 978-0801445019.
- Kemp, A. C., G. M. Kirwan, D. A. Christie, and J. S. Marks (2020). Reunion Harrier (Circus maillardi), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.reuhar2.01
- BirdForum Opus contributors. (2021) Reunion Harrier. In: BirdForum, the forum for wild birds and birding. Retrieved 12 May 2021 from https://www.birdforum.net/wiki/Reunion_Harrier