The marsh harriers are birds of prey of the harrier subfamily. They are medium-sized raptors and the largest and broadest-winged harriers. Most of them are associated with marshland and dense reedbeds. They are found almost worldwide, excluding only the Americas.

Until recently two species were generally recognized: the marsh harrier (Circus aeruginosus) and the African marsh harrier (C. ranivorus). The marsh harrier is now usually split into several species, sometimes as many as six. These are the western marsh harrier (C. aeruginosus), eastern marsh harrier (C. spilonotus), Papuan harrier (C. spilonotus spilothorax or C. spilothorax), swamp harrier (C. approximans), Réunion harrier (C. maillardi maillardi or C. maillardi) and Madagascar marsh harrier (C. maillardi macrosceles or C. macrosceles).

Source: Wikipedia