Hen harriers are to be bred in captivity in England for the first time and released on to Salisbury Plain in a new attempt to revive the endangered bird of prey in southern England.
The raptor’s only English breeding populations are on northern moorlands, where the bird has been subject to huge persecution in recent decades because its prey includes red grouse – a lucrative gamebird.
The hen harrier hasn’t bred in southern England for decades but it nests on the ground in lowland grassland and arable fields on the continent, and scientists believe it can thrive again on English farmland without persecution – if birds are returned there.
Twelve birds – six males and six females – have been brought from France and Spain to establish breeding pairs, in a Natural England project in collaboration with the International Center for Birds of Prey, which aims to release at least 100 birds over the next five or more years.
Young hen harriers in France were rescued from the wild overseas by volunteers, who ensure that if a harrier nests in a wheat field, the chicks are saved before the combines move in. Two additional birds are being brought in from Spain. The birds will begin to breed next spring, although the new pairs may not produce enough chicks for release into the wild until 2024.
Hen harrier pairs produce up to six chicks each year but they are timid and must be kept in special aviaries where they are not disturbed by noise or human activity.
Simon Lee, a senior adviser at Natural England, the government’s conservation watchdog, said: “The southern reintroduction project is an excellent example of international collaboration to drive species recovery. Working together, we hope to create a sustainable population which supports the long-term revival of this much-loved species.
“Hen harriers are a magnificent bird of prey, which sadly face many challenges including persecution and habitat loss. We are committed to driving down persecution to ensure permanent recovery of the species.”
Hen harriers have rarely been bred in captivity because they are considered by falconers to be “untameable”. Now considered an “upland” bird in Britain, where they feed mainly on voles while also taking some small birds such as meadow pipits, they were once widespread across the country before populations were decimated by persecution.
The University of Exeter researched suitable sites for reintroduction and concluded it made more sense to reintroduce them on to areas of grassland and farmland, which are commonplace in southern England, rather than isolated moorlands such as Exmoor and Dartmoor.
“They are not fussy birds at all,” said Lee. “Hen harriers just want vegetation of the right height and density in an open landscape for nesting and roosting; it doesn’t matter if it’s cereal crops or rough grassland or even potatoes. They will eat any available prey as long as it’s the right size. They are really generalists. From a reintroduction point of view, that gives the best opportunity in the quite anthropogenic landscapes we have in the UK.”
While much of Salisbury Plain is Ministry of Defense land, where the birds should therefore be free from persecution, Natural England has spent four years talking to farmers and game shoots in surrounding Wiltshire.
“We were nervous when we started to talk to people about it because of the history of persecution and the dynamic between conservationists and the shooting industry but we were very, very pleasantly surprised by the reaction,” said Lee.
“The overwhelming response was actively supportive. The one thing harriers have no impact on whatsoever is typical pheasant and red-legged partridge shoots. Harriers are way too small to take a pheasant.”
Hen harriers have spent winters in southern England since the 1970s so gamekeepers are used to seeing the birds around. “Harriers have been present in southern England in good numbers when the vast majority of shoots take place, to my knowledge without a single issue,” said Lee.
The overwintering birds have not settled in southern England because they often return close to their birthplace to mate and raise chicks, and also because there simply aren’t the numbers of harriers in the skies in springtime to encourage male birds to perform their famous “sky -dancing” aerobatic to attract a mate.
Releasing captive-bred birds will aim to create a southern breeding population of at least 100, after which it is hoped hen harriers will spread across the landscape as red kite populations have since their successful reintroduction in 1990.
The hen harrier was virtually wiped out in England and Wales by 1900 and after birds returned in the second half of last century they were almost wiped out again: no hen harriers bred in England in 2013. France has 10,000 pairs.
Recent conservation efforts have led to a revival in northern England: this year 119 chicks fledged from 34 hen harrier nests across uplands in County Durham, Cumbria, Lancashire and Northumberland, the most productive year for more than a century.
Part of this success is attributed to the government’s controversial policy of “brood management” whereby grouse shoots are given licenses to remove hen harrier nests, with the chicks reared in captivity and then released. This mechanism prevents the buildup of harrier nests on grouse moors, where they predate red grouse. But conservation groups including the RSPB are opposed to such management, arguing that does not confront the problem of illegal persecution.