Scientific name: Circus aeruginosus
Identification
Marsh harriers are the largest of the European harriers. They have long, broad wings and a long tail, with a slim body and long legs. Females are larger and are chocolate brown with a distinctive cream-coloured head. Males also have a paler head, but can be distinguished from females by their grey tail and tri-coloured wings: brown and grey with black tips. In flight the wings are held in a shallow ‘V’.
Habitat and Distribution
Marsh harriers breed in reedbeds and marshes, although are increasingly found in arable fields near wetlands. They are very widely distributed, being found throughout much of Europe and large parts of Africa and Asia. Within the UK the largest breeding populations are found in eastern England, with small populations in northern England and Scotland.
Global distribution of the marsh harrier (IUCN 2011)
Diet
Marsh harriers feed on species that live in or near wetlands. They take a variety of prey items, including small birds, chicks, ducklings and mammals, especially rabbits. Prey is caught by dropping onto it from the air.
Reproduction
Marsh harriers build their nests on the ground. The female constructs a nest from grass, reeds and small sticks, while the male builds one or two false nests nearby. Four or five eggs are laid at 2-3 day intervals and the female does all of the 31-38 day incubation, with the male hunting for both of them. Incubation begins with the first egg, resulting in a brood of different-aged young. Once the chicks have hatched the male continues to hunt for the whole family, with the female feeding the chicks. The young fledge at 35-40 days and the female remains with them for another 15-25 days.
Status and Threats
Marsh harriers are classified by the IUCN as ‘Least Concern’. However, they have suffered massive declines in the past and were seriously affected by the effects of organochlorine pesticides such as DDT in the 1950s and 1960s, which caused thinning of eggshells and a decrease in reproductive success. Current threats in the UK include deliberate disturbance of nesting sites, poisoning and illegal egg collection.
Within the UK marsh harriers are strictly protected under Schedule 1 of the Wildlife and Countryside Act 1981 and The Nature Conservation (Scotland) Act 2004. They are also included on the Amber List of UK birds of conservation concern. It is an offence to intentionally take, injure or kill a marsh harrier or to take, damage or destroy its nest, eggs or young. It is also an offence to intentionally or recklessly disturb the birds close to their nest during the breeding season. Violation can result in a fine of up to £5000 and/or a prison sentence of up to 6 months.
Internationally they are listed on Annex I of the Birds Directive and CITES and Appendix II of the Conservation of Migratory Species.
