Innovative wetland restoration techniques are helping to boost the bittern population at RSPB Minsmere in Suffolk.
The RSPB has reported this is the best year for bitterns since it started monitoring the bird's numbers, with more than 100 male booming bitterns recorded on the charity's reserves for the first time and almost 200 across the UK.
The organisation has hailed these figures as representing an "astonishing recovery" because as recently as 1997 the bittern was in danger of disappearing altogether in the UK when numbers dropped to 11 males, including just one at the RSPB Minsmere site, which over the past 20 years has become a haven for the bittern.
Despite its claim to fame as Britain's loudest bird, bitterns are highly secretive.
Well camouflaged in dense stands of reed, where they spend most of their time, bitterns are so elusive that scientists count them by listening for the males' distinctive booming call rather than by sight.
RSPB senior conservation scientist, Simon Wotton, said: "Bitterns are one of our most charismatic birds. Their astonishing recovery from the brink of extinction is a real conservation success story and an example of what is possible through targeted efforts to restore wildlife habitat.
"It's a delight to hear their distinctive booming call echoing across the reedbeds every year as more and more bitterns are making new or restored wetlands their home."
Habitat
Since 2006, there has been a year-on-year increase in the number of bitterns making their home in Britain. This year numbers reached record levels once more with 198 males recorded at 89 sites. This compares to 188 at 82 sites in 2018.
At Minsmere, eight booming male bitterns were identified along with two others at the nearby RSPB Dingle Marshes reserve while in 2018 there were nine at Minsmere and three at Dingle Marshes.
Minsmere's visitor experience manager Matt Parrott said the slight drop in numbers could be down to bitterns moving further into Suffolk, to locations such as Snape, Walberswick or Carlton Marshes, where reed restoration work has taken place.
Eight bittern nests were identified at Minsmere during 2019, the same as the previous year, with the RSPB team working on the basis that there is likely to be an average of two chicks per nest with one surviving.
The bittern's rarity is linked to the fact that it is restricted to a single habitat - wet reedbeds, which require a great deal of management work to maintain.
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Mr Parrott said at Minsmere, the team has been able to improve and expand this habitat by rotating the clearance of reeds, using livestock to manage it and changing the way the reeds are cut.
And these techniques have been copied at other sites, including the Somerset Levels, where 48 individual booming male bitterns were heard this year.
Pioneering
"Minsmere is a pioneering site," said Mr Parrott.
"Because it is so large we are able to compartmentalise areas, and have a bit of a play and try new techniques to see if they encourage species to move in.
"We've been using Highland cattle more in these areas - they smash through the reed beds and push it down and help to create a variety of,areas ‑ some where there are lots of reeds and areas where they are sparse. Their dung acts as fertiliser, to help reeds grow back and the natural cutting of reeds means there are more places for bitterns to nest and feed.
The Minsmere team are also using Konik ponies to graze grassland areas. The breed closely resembles a type of ancient pony that used to live on these shores and is hardy breed that can cope with wet conditions.
Mr Parrott said now is a good time to see bitterns at Minsmere, as much of the reed near the Island Mere hide has been cut back, so there is less coverage for the birds to hide in.
Visitors during the autumn are unlikely to hear the bittern's booming, however, as this takes place in February when the males are looking to attract females.
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