Bitterns Nest in the Fens for the First Time Since Before the Second World WarThe recovery of the bittern - one of Britain’s most threatened birds - has taken a tentative step forward in 2007 with news that male bitterns were recorded at more sites than any other year since 1990, when detailed annual monitoring began. Significantly, the survey has revealed that these sensitive birds have been recorded nesting in the East Anglian Fens for the first time since before the Second World War. Evidence of four nests were found at a single, privately-owned site in Cambridgeshire involving three different breeding females. This is also the first time that bitterns have been recorded nesting in a newly-created reedbed; the bird’s preferred habitat.Dr Mark Avery, the RSPB’s Conservation Director, said: “The spread of the bitterns into areas of newly-created reedbeds is a testament to all those involved with habitat creation, especially in the East Anglian Fens. Reedbed sites occupied by more than 40 per cent of male bitterns this year are at risk. Rising sea levels threaten to inundate eight freshwater reedbeds, increasing salinity and making them unsuitable for this sensitive bird. Encouraging bitterns to nest in newly-created sites away from the coast helps to buffer these sensitive birds against the impacts of climate change and will help safeguard their future in Britain.”Extinct in Britain between 1886 and 1911, the bittern reached a second low point in 1997, when the bird’s population dropped to 11 males. However, 10 years on, surveyors from the RSPB and Natural England recorded a minimum of 51 male bitterns across 33 sites, giving encouragement to everyone involved with the conservation of this bird. This year’s total is a 16 per cent increase on last year’s figure of 44 males, and only four behind the recent record of 55 males in 2004. Bitterns nesting in the UK are confined to reedbeds. RSPB research in the 1990s showed that reedbeds containing bitterns were drying out, leaving the bird with little suitable habitat leading to a perilous population decline.
Being a secretive bird of dense, extensive reedbeds, the bittern is a difficult bird to census. Historically, researchers have relied on listening for the male’s ‘booming’ call to help gauge the population. However, more recently, scientists have also identified locations of nests with chicks in the hope of providing a more accurate reflection of the nesting success of bitterns. This year evidence of a minimum 27 nests with chicks were found; the same as the preceding two years. The measure of actual nesting effort provides a more reliable indicator of recovery.As a nesting bird in the UK, the bittern is confined to England with East Anglia containing more than three-quarters of number of ‘booming’ males and a minimum of 24 nests with young. North-east England, mostly at sites around the Humber, with nine ‘booming’ males is also a key area for the recovery of this bird, although only one nest with young was recorded in 2007, compared with five nests with young in 2004.
Dr Tom Tew, Natural England's Chief Scientist, said: “Bitterns are booming again: after two poor breeding seasons numbers are on the increase. Natural England and its partners are committed to creating new wetlands and the bittern's success at newly created reedbeds is an example of how effective we can be. Climate change is one of the greatest threats facing wetland wildlife and we are searching for ways to make them more resilient. We hope the wetlands created at Lakenheath Fen, the Great Fen and in the Somerset Levels will soon be attracting bitterns too.”Dr Mark Avery, the RSPB’s conservation director, added: “We should be encouraged that the bittern is showing signs of recovery, but we must not let this bird slip through our grasp again.”
Flash flooding over the Whitsun bank holiday weekend affected nine bittern nests this year. Some nests were flooded out while chicks in others may well have died of starvation or hypothermia.
Sadly, there were no reports of male bitterns from South West England, Wales or Central England this year, and there was only a single booming male from South East England, at a site last occupied in 2004. The fortunes of the bittern in North West England fared a little better this year with reports of two nests with young at the RSPB’s Leighton Moss reserve: and a booming male from the Wigan Flashes.
Conservationists are particularly excited that Kingfisher’s Bridge - a privately-owned newly-created site in Cambridgeshire - has been the centre for recolonisation of the Fens. The 150-acre wetland site - which in 1995 was Grade 1 arable land - has been partially converted to reedbed by the landowner Andrew Green, with help from wildlife consultant Roger Beecroft.Andrew Green, the landowner, said: “After all our hard work, we are delighted that bitterns are nesting again in the Fens. We think the key to the project’s success is dependent upon a number of factors: good evidence-based habitat management; pure water and control of water levels; .the creation of a rich fishery, providing excellent feeding opportunities for bitterns; and the rigorous control of foxes and mink. We are grateful to the RSPB for its research into bitterns, which has helped design an ideal site, and for the supply of reed seeds.”
Dr Mark Avery added: “If we thought about it, the RSPB might just be a little envious that Andrew Green has been the first landowner since 1938 to have nesting bitterns in the Fens. We congratulate Andrew on his fantastic achievement and look forward to the spread of this fantastic bird to its rightful home in the heart of East Anglia and, hopefully, to our fenland recreation sites too! The Bittern Monitoring Programme is jointly funded through Action for Birds in England, a conservation partnership between Natural England and the RSPB.
4th July 2014