The western marsh harrier – Circus aeruginosus is a largest harrier, a bird of prey from western Eurasia and adjacent Afrca. It is also known as the Eurasian marsh harrier. The genus name Circus is for its circling flight (kirkos, “circle”), the specific aeruginosus is Latin for “rusty”.
The western marsh harrier is 43 to 54 cm – (17 to 21 in) in length, has a wingspan of 115 to 130 cm (45 to 51 in) and a weight of 400 to 650 g (14 to 23 oz) in males and 500 to 800 g (18 to 28 oz) in females. It is a large, bulky harrier with fairly broad wings, and has a strong and peculiar sexual dichromatism.
Most populations of the western marsh harrier are migratory or dispersive. Some birds winter in milder regions of southern and western Europe, while others migrate to the Sahel, Nile basin and Great Lakes region in Africa or to Arabia, the Indian subcontinent and Myanmar.
It feeds on small mammals, small birds, insects, reptiles, and frogs.