Seeking a phantom: Bitterns in Herts
PUBLISHED: 09:30 30 January 2016
Tim Hill, conservation manager at Herts and Middlesex Wildlife Trust, has been down in the reedbeds searching for one of the UK’s most elusive and rare birds
Deep in the swamp something is stirring. It’s invisible at first, then a large yellow eye blinks. The toes of a bony green foot stretch out and a dagger-like beak snaps. A low ‘grrrrrr’ can just be heard above the swish of the wind-blown reeds.
This isn’t the opening scene from a science-fiction alien movie but the first experience of watching a bittern on an early January morning from the public hide at Amwell Nature Reserve in the Lee Valley near Broxbourne. Bitterns are never easy to see, given their almost perfectly camouflaged brown and black feathering and their usual habit of skulking in reedbeds, and an eye or a foot is sometimes all one will see. Patience and a bit of luck are needed for a view of a whole bittern.
The booming bogblutter
One of the bittern’s most distinctive features is its mating call or ‘boom’. Bitterns have a deep, fog-horn like call which can be heard from a great distance across the reedbeds. Male bitterns begin to boom as early as late January to establish territories and attract mates.
Their habitat, booming call and the fact they were widespread in England up to the 17th century gave rise to a number of local names, including bogblutter and bull of the bog. The bittern was once hunted for the table, leading to its other name of butterbump in some areas because, when cooked, a large amount of fat is produced.
Today bitterns are a Red List species - one of the most threatened in the UK. In 1997 there were only 11 booming males in Britain but thanks to concerted conservation work there were 150 recorded ‘boomers’ in 2015. During the winter, it is estimated there are around 600 birds in the UK as resident numbers are boosted by the arrival of birds from the continent.
Bitterns eat fish, therefore a crucial component in maintaining their population is to ensure there are reedbeds in water that have sufficient fish of a suitable size for bitterns to catch and eat. A UK biodiversity action plan for bitterns is directing the conservation effort and in the past 15 years two national projects have secured funding from the European Union LIFE Nature Fund to restore and create new reedbeds for these elusive birds.
Bitterns in Herts
At present, while bitterns do spend winter in Hertfordshire they haven’t yet bred, in spite of the occasional booming bird in early spring. The most reliable place to see bitterns in the county is at the Herts and Middlesex Wildlife Trust’s Amwell Nature Reserve, but it’s no happy accident that bitterns visit here. The reserve is now one of the most biodiverse in the country, a site of special scientific interest and part of the internationally-important Lee Valley Special Protection Area. A carefully designed restoration plan, complemented by a huge amount of voluntary conservation work over the past 35 years, has resulted in a reserve which is enjoyed by thousands of visitors every year.
In addition to Amwell, sightings of bitterns have also been made further up the Lee Valley at Rye Meads Nature Reserve, in former gravel extraction pits in Cheshunt, Tring Reservoirs, Hilfield Park Reservoir at Elstree and Stocker’s Lake, Rickmansworth. With only 23 hectares of reedbed in Hertfordshire and probably only half of that wet and containing suitable fish populations, there is much work required to ensure bitterns continue to visit the county.
In October 2015, Herts and Middlesex Wildlife Trust won a judge’s commendation at the Campaign for the Protection of Rural England Hertfordshire awards for its work on the reedbeds at Amwell. The work, funded by Veolia Environmental Trust, East Herts District Council and Herts County Council, was completed last June and created new ‘rides’ cut through reedbeds, new ditches, re-profiling of the lake edges and expanded bays to create new feeding habitats along the wetland margins. This work has helped to create a habitat for bitterns that will hopefully see them booming in greater numbers in Hertfordshire in years to come.