About Circus maillardi J.Verreaux, 1862
Circus maillardi J.Verreaux, 1862, commonly known as the Réunion harrier, measures 42 to 55 cm in total length; females are approximately 3 to 15% larger than males. Mature males have blackish heads and backs marked with white streaks. Their underparts, underwings, and rumps are white, their tails are grey, and their wings are a mix of grey and black with a distinct white leading edge. Females and immature individuals are dark brown, with a white rump and a barred tail. These birds are mostly silent outside of the breeding season; during breeding, they produce a chattering threat call, a wailing courtship call, and chuckling calls associated with obtaining food. Compared to the closely related Malagasy harrier, the Réunion harrier is larger and paler, with longer wings and legs. The Réunion harrier occupies a very broad habitat range, extending from open and semi-open landscapes such as degraded forests, shrublands, savannah, sugarcane cultivated fields, and pastures, to dense native forests located in steep canyons. They rarely inhabit Acacia forests above 1200 meters elevation, but can be found at elevations up to 1600 meters. During the breeding season, they are most commonly found in native and degraded lowland evergreen forests. Breeding occurs between January and May; the species lays two or three white eggs in a nest built on the ground. Today, the Réunion harrier's diet consists largely of introduced mammals including rats, mice, and tenrecs; historically, it fed mainly on birds and insects. Small lizards, frogs, and carrion are also part of the species' current diet. The Réunion harrier has several unusual adaptations not commonly seen in other harriers: it has broad rounded wings suited for hunting between trees, along with a short tarsus and long claws, traits common among birds of prey that hunt other birds. Although the Réunion harrier is morphologically adapted for hunting in forest habitats, it typically avoids closed forest canopies following the shift in its diet, as the introduced mammals it now preys on are difficult to find in this closed old-growth environment.
