FIELD NOTES
NOVEMBER 2002 continued....
ARTICLES
Bitterns In The Lea Valley
"In the Lee Valley, just north of London, there is a hide overlooking a small reed-bed where numerous birdwatchers have had spectacular views of Bitterns in the last few winters. It is called the Bittern Watchpoint and outside the hide there is a giant, coloured cut-out of a Bittern pointing its long beak at the sky. You might think you were passing some quaint rural cinema. I have watched a Bittern at a yard or two's range there, marvelling at the way its streaky plumage blends with the reed stems and gazing deep into its fishy eye........"
Derwent May, writing in the Times on 1st March 1997
Derwent May isn't alone. Since its opening in 1996, over 50,000 people have travelled from all over Britain to the Lee Valley Regional Park's Bittern Watchpoint at Fishers Green. Few leave disappointed. According to Bill Oddie, "The Bittern Watchpoint provides probably the best place in the world to see Bitterns in their natural surroundings."
However, it wasn't always so. Until the late1960s the Bittern was an irregular visitor to the Lee Valley. During the 1970s and 80s between one and two birds wintered with numbers rising to six or seven during the severe winters of 1978 and 1981, when birds may have arrived from even worse conditions elsewhere in mainland Europe. Since 1991, numbers have steadily increased to an average of five to six birds in the late 1990s. This increase mirrors the establishment and growth of reed-bed habitat in the Lee Valley.
Reeds have slowly colonised flood meadows and the margins of gravel workings. Equally important are abundant food supplies for Bitterns. The slow, natural development of fish populations has been augmented by anglers, who have artificially increased fish stocks in many waters. Another positive feature of the Lee Valley is that there are numerous rivers, streams and flood relief channels. During freezing weather these remain ice-free and continue to provide feeding areas for Bitterns.
The creation of the Bittern Watchpoint arose out of an action plan to conserve Bitterns and their habitats in the Lee Valley. Produced in 1996 by a partnership of eleven organisations, the Plan was the first of its kind, setting local targets for the conservation of this nationally rare bird. Within a few years, the Plan was revised and incorporated within the Biodiversity Action Plan for the Lee Valley Regional Park, published in 2000. The objectives for Bitterns and reed-beds are to: -
- Maintain all existing reed-beds by appropriate management.
- Complete site management plans/statements for all reed-beds.
- Produce at least 2 large reed-bed complexes by creating 10 ha at Cheshunt gravel pits and 10 ha at Rye Meads within 5 years.
- Increase the number of small reed-beds by creating a total of at least 5 ha at other sites.
- Increase the number of wintering Bitterns to 10 within 10 years.
- Increase the number of regular wintering sites to 4 within 10 years.
- Attract at least 1 booming male within the next 10 years.
The Rye Meads Ringing Group is co-ordinating implementation of the plan. Significant habitat enhancement and creation work has been carried out by the Lee Valley Regional Park, RSPB, Environment Agency and Herts and Middlesex Wildlife Trust. Effort has been concentrated at Rye Meads, Turnford and Cheshunt Gravel Pits. At Amwell Quarry Nature Reserve, volunteers working with Ready Mixed Concrete Ltd have created large areas of reed. It is encouraging to note that in recent winters Bitterns have been regularly using reedbeds that have been created or enhanced over the past five years. A few years ago a young Bittern fledged from the RSPB reserve at Minsmere spent a few weeks in the Amwell reed-bed.
In September 2000 the Lee Valley was declared as a Special Protection Area and Ramsar site. One of the reasons for this European importance is that it is used regularly by 10% or more of the Great Britain wintering population of Bittern, which is estimated at only 100 individuals.
Eleven birds were present in 1998/99 and during the winter of 2001/2002 between ten and twelve Bitterns wintered in the Lee Valley which could be as much as 12% of the British wintering population! This total included two at Amwell, two at Rye Meads, one at Nazeing, four to six at Turnford and Cheshunt Gravel Pits and one at Walthamstow Reservoirs.
So what of the future? Last year the Regional Park, Herts and Middlesex Wildlife Trust and Ready Mixed Concrete Ltd joined a national partnership, co-ordinated by the RSPB and made a successful bid for European LIFE Nature funding to create a strategic network of reed-beds for Bitterns across the country.
In the Lee Valley, the project will fund the extension of existing reed-beds and the creation of new ones at Amwell, Rye Meads and 70 Acres Lake in line with action plan objectives. The stage will then be set for the wintering bitterns of the Lee valley to be joined by breeding birds. This is not just a pipe dream. As recently as 1999 a male Bittern boomed throughout the spring at Tring Reservoirs but as far as we know never attracted a mate.
For those of you who want to see the wintering bitterns at Fisher's Green the Watchpoint is open at weekends or by special arrangement in the week. The first Bitterns are usually seen in October although mid-winter is the best time to go.
Tim Hill
The Kimpton Floods
Although this article is a bit away from our normal format I thought it worth recording one of the effects of the very wet autumn/winter 2000/2001.
Living in Kimpton I was surprised to see, in February, a couple of fire appliances in the village. These were the early part of what was to turn into a huge logistical operation as a result of the re-emergence of the River Kym.
To many people living in the village the existence of the river came a surprise since it had not flowed since 1947. This was particularly so for those businesses and householders occupying buildings on the course of the River! For a time much of the village was threatened by severe flooding from a number of lakes that had formed upstream towards Luton Airport, and which seemed likely to burst their banks.
As a result of a great deal of time, effort and money from North Herts District Council the threat was contained although even as I write in June pumps are still operating to keep the situation under control.
The River Kym is a subsidiary of the Mimram and originally joined it at Kimpton Mill. The Mimram flows from below Breachwood Green/Kings Walden via Whitwell and eventually joins the Lee at Hertford. For sometime in the mid 1990's the Mimram was also dry above Welwyn.
So what effect has all of this water had?
- In the Kym valley above the village not very much. The lakes were used by Mallard, Lapwing and Gulls during the winter
- Below Kimpton there has been noticeable effect. At Kimpton sewage works a small lake was formed and up to 15 Gadwall, 6 Teal and many Lapwing were recorded there in late winter and spring. The water flows via the sewage works settling lake into the old cress beds and thence into the Mimram.
- The Mimram valley above Whitwell has had some very dramatic changes. From a lake formed below Kings Walden the river has forced its way along its historic course across the fields and into an area of sink holes at TL 166226. To my recollection these were last full in 1994/5 when Redshank bred. To illustrate the depth of these there were at least 15 Tufted Ducks on the site in spring and it looks as though some have remained to breed.
- Below Kimpton Mill the Mimram continued to force its way along an old course across the grazing meadows, as well as keeping the main river very wet. 75 Moorhens in one field in March where there were none last year show that conditions are slowly improving and Little Grebes have bred this year.
Robin Smith
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