Digswell Lake Society

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Newsletter

Early Summer 2010

Diary Dates 2010 Monday 21st June 2010

200th Birthday of the opening of the Lake

Open evening for the public between 6pm and 8pm

Friday 25 June 2010

AGM + Understanding Hertfordshire Scenery

Speaker Mike Howgate.

Mike has made a particular study of the underlying geological

effects on the countryside.

Friday 8 October 2010

Birds in Hertfordshire

Speaker Brian Sawford.

Brian is a retired Countryside Officer having worked with the

North Herts District Council and author of several books on the

country side.

Friday 26 November 2010

Video Presentation with a Nature Theme

Speaker John Astin.

John is a long standing member of the Potters Bar Cine and

Video Club. gh

Chairman’s Column

The 200th birthday of the Lake on 21 June 2010 will be celebrated by opening it to the public that evening (6pm-8pm).

Why was it ever created in the first place? The obvious answer is, to be an ornament to Digswell House, which (back in 1810) had itself only recently been completed. This leads to the next question, why do so many great houses have lakes? Even locally, there are lakes at Panshanger House (where the lake has outlasted the house), Brocket Hall, Luton Hoo, St Pauls Walden Bury..,

Certainly, a lake must have been a status symbol, showing off the wealth of the owner who could afford to have the work done.

However, I think it goes deeper. Our aesthetic sense responds to water and grassland and trees because, over millennia, humans have come to learn that they need these things - grassland for agriculture and grazing, water for drinking, and trees for fuel and building material. And now that life is, thankfully, no longer an elemental daily battle for survival, we can enjoy places such as Digswell Lake through our higher senses, grateful that the landowner 200 years ago shared our concept of landscaped beauty and that it has survived all this time, regardless of the changes around it.

Visitors to our Open Evening will find their way round more easily, thanks to the new map which I’m glad to say is at last in place near the entrance.

Visitors who come in through the gap in the fence in

Bessemer Road

are now confronted by another map, which explains that the Lake belongs to this Society. In the past, many such visitors, when politely asked whether they are Members, have claimed not to know about the Society; they don't have this excuse now.

Shortly after the 200th birthday, we have our Annual General Meeting on 25 June 2010 (7.30pm). I hope I shall see you there. Fuller details are enclosed with this newsletter, including how you can put yourself forward for election to the Committee, if you feel you have something you would like to contribute. This is no empty political rhetoric - we do have a couple of vacancies, and you would stand a good chance of being elected.

Our hedge along

Bessemer Road

could do with being “laid”, about which the Borough Council’s ecology staff have been very helpful in the past. We had hoped this work might have started this spring, in a number of annual stages along the length of the hedge. However, with our hedge being on the north side of the road verge, the trees (mainly ash) growing on the verge (and thus belonging not to us but to the Council) are depriving our hedge of sunlight. In normal circumstances, these ash trees would be reduced as a matter of routine if only to maintain clearance for road traffic, but following the Council’s bruising experience over the Stanborough poplars, it is adopting a much more cautious approach to radical work on any tree. For us, this means that the ash trees will continue to overshadow our hedge for the moment, effectively delaying the hedge-laying until at least Spring 2011.

Because the Lake grassland is purely ornamental, it has never been treated with fertiliser or weedkiller (at least never in the 53 years of the Society having managed it). This makes it of some considerable scientific interest, and the results of a survey conducted at the Lake in 2009 are summarised elsewhere in this Newsletter. The surveyors confirmed that we comfortably exceed the criteria for retaining our important designation as a County Widlife Site, and even suggested that the Lake might qualify as a Site of Special Scientific Interest. However, we are unsure about applying for SSSI status as it might unacceptably constrain even our normal management and maintenance.

Peter Neville

Membership Secretary’s Report

Membership levels have remained buoyant during the past year; a steady trickle of new members has counterbalanced the losses and we have had some sad losses; John Akers, a well known local painter who painted many views of the Lake and had been a member for some years, died suddenly before Christmas. Mr George Sale also died earlier this year and kindly left the Society a legacy of £100.00. We are very fortunate in the breadth of interest and support we derive from our members.

I know that many people aspire to attend the work parties, myself included, and just don’t have the time or have other commitments. One of our unsung heroes is Hamish Ritchie who has had major heart surgery recently but has always tried to contribute to the maintenance of the Lake environs. He cannot make the weekends but does a ’litter pick’ walk most weeks. Many thanks to him and to all the other members who remove the odd vodka bottle and sandwich package on their visits to the Lake. As we come up to the start of the summer holidays these efforts will become even more valuable.

We hope that existing members will also visit us at the Lake on our Open Evening. If you haven’t been for a while use this as an opportunity to renew your aquaintance and we would love to see you.

Best wishes for the Summer

Carole Dale

Romania

I have just returned from a wonderful wildlife watching trip in Romania which was organised by the SE Herts. RSPB Group.

After flying to Bucharest (narrowly missing the volcanic ash from

Iceland) we spent the first few days in the Carpathian Mountains and Transylvania – Dracula country! Our only contact with Dracula was to drive past Bram Castle where the real Dracula – Vlad the Impaler - may have spent the night in the 15^th century. Much more exciting was watching brown bears from a hide deep in the forest with the moon rising over snow covered mountains.

We then drove to the Danube Delta, Europe’s greatest and wildest wetland at the end of the 2840km River Danube. The river rises in Germany’s Black Forest and flows into the Black Sea off Romania after passing through ten countries and four capital cities.

Our accommodation was a very comfortable hotel boat pulled by a tug. We had a small boat to take us up the narrow channels. We spent each night moored in a different spot miles from anywhere and waking up to the call of bullfrogs and booming bitterns.

The first morning was magical as we drifted, with no engine, listening to thrush nightingales and watching dozens of kingfishers cross our path. I saw an amazing number of birds including glossy ibis, herons, white tailed eagles, pygmy cormorants and rollers. Huge flocks of white pelicans glided overhead while whiskered terns, black terns and white winged black terns gave wonderful displays of their flying skills.

The last couple of days were spent in the Macin Mountains and the marshes of the Black Sea coast where we saw more species of birds and also lovely wild flowers like lady orchids, monkey orchids and wild peonies. We saw red squirrels, hares, tortoises and some ground squirrels called susliks.

Travelling in the Romania countryside was like going back to medieval times with strip farming and shepherds herding sheep and cattle. A fascinating trip.

Jenny Brewster

Digswell Lake Bird Report

March 2009 - March 2010

Compiled and submitted by Colin Hull

Acknowledgments

Thanks for some people who have sent me a few reports during the year and particularly for the information sent by Tom and Janet Gladwin. I think they actually do more visits to the lake than me.
Highlights For the second year running a pair of Mute Swan nested. Sightings of Common Buzzard have increased. One reported flying over the lake and Tom reported one roosted at the lake Oct-Feb. Other unusual sightings from Tom include a Raven on 20^th Oct and 11^th Nov and a juvenile Hobby on 23^rd August.
Full systelatic list
For most species I have included some notes on the national status and the population trends from data by the British Trust for Ornithology.

Key. SV summer visitor, WV winter visitor

Birds of national conservation concern. Red list >50% decline, Amber list 25-50% decline

Little Grebe. National population trends are uncertain with better breeding success on ponds rather than rivers. One pair was present during the summer but I did not observe any nests or young. At other times there was one regularly through the 2009/10 winter.

Grey Heron. The national Heronries Census showed 12,959 nests in 2008. There have been moderate increases overmuch of the UK. One on the river near the viaduct on some dates.

Little Egret. Has shown rapid increase in numbers and geographical range in the UK. There were reports of singles on the river nearby in winter months.

Mute Swan. The national population had been fairly stable since the 1960s, have increased progressively since the mid 1980s, perhaps reflecting warmer winter weather and the replacement of anglers' lead weights. After last year’s return as a breeding species this year four eggs were laid but only one hatched. The juvenile was seen on several occasions later in the year.

Mallard. The population has increased steadily as a breeding bird in the UK since the 1960s, and especially in England, a trend to which ongoing large-scale releases for shooting may have contributed. However at the lake numbers at the lake have continued declined. There was a maximum of 5 (3 males, 2 females) on several dates in the 2009/10 winter. During the summer I saw one brood of 8 young.

Gadwall. Regular visitor but only rarely breeds at the lake. 2 pairs seen on some visits but no evidence of breeding. Small flocks in winter months with maximum of 18 on 17th January, 2010.

Tufted Duck. Frequent visitor with occasional breeding. This year no noted breeding but occasional visits of 2-4.

Shoveler. (WV). Up to 4 regularly throughout the 2009/10 winter.

Canada Goose. The species were first introduced to English parkland around 1665 but have expanded hugely in range and numbers following translocations in the 1950s and 1960s. Two (possibly a pair) were seen on some visits but did not breed on site.

Pheasant. Have increased in abundance since the 1960s, at a rate that appears to be accelerating. 1-2 seen on some visits but no proven breeding on site this year.

Common Buzzard. Has shown big eastern expansion in recent years and returning to Home Counties as breeding species. One reported to me overhead 1^st March 2009. Tom also reported one rooting at the east of the lake from October to early February.

Kestrel. Amber list. The national population has been fluctuating. Although there has been substantial increase in the number of fledglings per breeding attempt a subsequent decline has resulted in the inclusion of Kestrel in the Nest Records concern list.

One pair nested and two young fledged and some alarm calls in July may have indicated that the young were present.

Hobby. (SV). Has shown a large increase in

southern counties in recent years. At the lake a juvenile occurred 23rd August. This was probably one of the three that fledged from a nest along Tewinwater.

Moorhen. National population is fluctuating with no long-term trend. The failure rate of nests over the full 25-day egg period (20 days for incubation and 5 days for laying) has increased, earning the species a place on the nest records concern list. 3.pr occuredc during the breeding season. A few nests were found but all the outcomes were uncertain. On the other hand some juvenile Moorhens were seen so there must have been a few successes.

Coot. Nationally there has been a rapid increase on waterways. There were three pairs of Coot on site, two on the lake and one beyond the dam. The west end pair had a brood of 4 chicks and middle lake pair had a bumper brood of 7 chicks. However on a late date only 5 were seen. The pair beyond the dam were seen with one juvenile later in the summer.

Stock Dove.. There was 3 pairs in the breeding season.

Wood Pigeon. One of UKs most abundant species with 2.7 – 3.1 million territories in 2000. At the lake there 7 pairs and many others all year. There was a maximum of 200+ on 11th October.

Black-headed Gull. (WV). Small numbers regularly on the lake in the afternoon throughout the winter.

Tawny Owl. Being a nocturnal species it is difficult to monitor but population is probably stable. No records on site for this year but a pair bred just off-site.

Kingfisher. Amber List. There was a decline along linear waterways (its principal habitat) until the mid 1980s, since when it seems to have made a complete recovery. Amber listing of this species in the UK results from its 'depleted' status in Europe as a whole, following declines between 1970 and 1990. The only record for the lake was a one report to me on 15^th June.

Green Woodpecker. Populations have risen steadily in Britain since 1966. 24,200 pairs in 2000. At the lake one calling and seen on several dates.

Great Spotted Woodpecker. This species increased rapidly in the 1970s and began a further increase in the early 1990s. Numbers have also risen widely in Europe since 1980. At the lake one drumming and also heard on some other dates.

Grey Wagtail. Grey Wagtails occur at highest densities along fast-flowing upland streams. Elsewhere a probable moderate decline. At the lake occasional visits but no proof of breeding on site.

Pied Wagtail. Britain and Ireland together hold almost the entire population of the distinctive dark-backed race yarrellii, and for this reason population changes in the UK are of global conservation significance. Occasional visits but no proof of breeding on site.

Wren. Annual numbers are influenced by mortality rates that may be very high in severe winters and by the species' high breeding potential. Up to 5 singing males noted on some visits but Tom noted 11 breeding pairs plus some alarm calls indicating young birds were present.

Dunnock. Amber List. Abundance fell substantially between the mid 1970s and mid 1980s, after a period of population stability. Some recovery has occurred throughout the UK since the late 1990s. 1-2 singing males heard on some visits but no other proof of breeding.

Robin. National population has increased markedly since the mid 1980s, having been set back earlier by a succession of cold winters. Up to 6 singing males on some visits but Tom noted 14 territories.

Blackbird. Various census schemes have show long-term declines in abundance, but recent increases indicate that the population has begun to recover taking it off the Amber

list. On site 3 pairs present with evidence of breeding.

Song Thrush. Red List. A rapid decline in abundance that began in the mid 1970s. Recent data has show a general increase, but population levels remain relatively low compared to the 1970’s. On site 1-2 singing males but no other breeding observations.

Mistle Thrush. Amber list. Declined significantly since the mid 1970s, especially on farmland.

The species was recently moved from the green to the amber list because of population decline. 2 singing males on various dates.

Redwing (WV). Showed up in low numbers in early March 2009 after previous flocks seen in February and were seen feeding under the trees by the river. In this case probably feeding ready for departure back north but none observed in later winter season.

Backcap. (SV). Abundance has increased consistently since the late 1970s, a trend common to all habitats. Three singing males on several dates.

Garden Warbler. (SV). Numbers have shown widespread moderate decline across Europe since 1980. 2 pairs

Chiffchaff. (SV). Chiffchaff abundance crashed in the late 1960s/early 1970s in common with that of other trans-Saharan warblers. After remaining stable for a decade, the population recovered strongly, and has continued to increase. Four pairs noted on site.

Goldcrest. Fluctuating populations depending on winter survival. 1-2 heard singing but no further breeding records. A few with Tit flocks in winter months.

Firecrest. Migrant. A male was seen on 11th October.

Long-tailed Tit. Progressive increases in abundance beginning in the early 1980s. 3 prs occurred on site. Some flocks of young families noted on site. 31 counted on 11^th Oct.

Blue Tit. Populations have increased in abundance, with brief pauses in the long-term upward trend. Present on all visit dates and 8prs but I have no breeding records. Large flock of 128+ on 11 Oct with other Tits.

Great Tit. Increased steadily since the 1960s, with the exception of two brief periods of stability or shallow decline during the mid 1970s and late 1980s. Present on all visit dates and 3prs. 39+ counted on 11^th Oct.

Coal Tit. No data for breeding but 3 with other Tits on 11^th Oct.

Nuthatch. National abundance has increased rapidly since the mid 1970s. Despite minor setbacks during the 1990s, there is no indication yet of a halt to the upward trend. 2prs and singles noted on a few dates.

Tree creeper. The UK population peaked in the mid 1970s, but has been roughly stable since about 1980 with 214,000 territories in 2000. One seen on a few dates possibly indicates 1 breeding pair.

Jay. 160,000 territories in 2000 and some increase in the recent ten-year period. One or two families on site.

Magpie. National population increased steadily until the late 1980s causing some concern about their predation of song bird nests. 650,000 territories in 2000. But abundance stabilised and a minor decrease has been recorded in the UK during the last five years. Present on most visits. 1 nest on site failed.

Jackdaw. Nationally increase in abundance since the 1960s. This has been associated with improvements in breeding performance and probably reflects the species' generalist feeding habits. 9 pairs observed near the entrance and nesting in the trees. Outside the breeding season small flocks up to 20.

Raven. New to the lake list. National population estimated to have increased by 118% across Europe during 1980–2006: One overhead on 20th October and 11th November. Tom reports they are now regularly seen over his bungalow.

Carrion Crow. National population has increased steadily since the 1960s and only now are there any signs of the UK population size stabilising. This trend has been associated with increases in nesting success and with earlier laying (perhaps an effect of climate change). A few present on most visits with 1 breeding pair.

Chaffinch. National abundance has increased rapidly since the early 1970s but numbers seemed to stabilise for a period during the 1990s. 3 pr. present on some visits.

Goldfinch. Abundance fell sharply from the mid 1970s until the mid 1980s, but the decline was both preceded and followed by significant population increases. The recent upturn has lifted the species from the amber list of conservation concern into the green category, and has been accompanied by an increase in its use of gardens for winter feeding. Present on a few visits 2pr in the breeding season.

Bullfinch. Red data species. The national population entered a long period of decline in the mid 1970s, following a period of relative stability. The decline was initially very steep, and more so in farmland than in wooded habitats, but has been shallower since the early 1980s. Not recorded this year.

Siskin (WV) A flock report to me on the 1^st March 2009 was of a flock of over 100. A few visits Jan-Mar this year including the very cold snowy period showed only small flocks with max 30.

Redpoll (WV) Sometimes occurs with Siskin. A max of 9 present irregularly until 5th April at least.
In addition to the birds it is good to report that a Water Vole was seen several times along the river.

Thanks to all those who take an interest in the bird life of the lake. We will ask again kindly that those people who walk dogs to please keep to the main grassy areas of the reserve from Mar-August so as to avoid disturbing nesting birds.

If you have any interesting sightings or information in connection with birds at the lake please contact me. With regard to sending me sightings of birds you cannot identify, I recognise that fleeting glimpses may be difficult to be certain about. If you get a good look at the bird then try and make some mental notes (or even write them down at the site).

How big is it? (Sparrow size, Blackbird, Crow size etc)

Main colours on back, head, tail, underneath

Is it perched or walking /swimming?

If it is flying does it fly it in straight line or up and down?

Are the wings rounded or pointed?

Colin Hull.

Tel 01438 813074

Email: colinhull88@btinternet.com

Digswell Lake Wildlife site survey: 25.06.09

Site No: 57/007 Grid Ref: TL243148 Area: 5.74ha District: Welwyn Hatfield

Surveyors: John Moss, Jean Williamson, Donald Scott

Location/Aspect. Flat, open aspect, west of Digswell. Geology/Soils. Lea gravels

Site description. This ornamental lake was created in 1810 as part of the Digswell House Park. It is fed by underground springs and discharges over a weir into the River Mimram. In 1957 the Digswell Lake Society was formed to manage 17 acres of woodland with the lake, for conservation and recreation, acquiring the freehold in 1985. The site includes a mosaic of habitats; the lake with good aquatic flora, tall swamp, wet semi-natural mainly Alder woodland straddling the Mimram, semi-improved neutral grassland, ancient parkland trees and young mixed broad-leafed plantation woodland. 133 plants were recorded, including 16 ancient woodland, 6 fen, 8 neutral grassland and 5 wet grassland species and a number of non-native species.

The south side of the lake is mainly mown amenity grassland, with rougher margins and a relatively high proportion of herbs, including Selfheal, Germander Speedwell, Creeping and Meadow Buttercup, Daisy, Knapweed, Cowslip, Lady’s Bedstraw and Lesser Stitchwort. Grasses are mainly Red Fescue, Meadow Foxtail, Meadow-grass and possibly Bents, with Yorkshire Fog, Cocksfoot and False Oat in the un-mown margins. There is a belt of young planted mixed trees, mainly native, between the grassland and site boundary.

The area at the east end up to the railway viaduct on the boundary is mainly young regenerating Alder over dense nettle beds and marsh along the river. This apparently follows much ground disturbance some years ago to install a main sewer. 20 Cricket Bat Willows were also recently planted by a contractor here.

The lake is relatively shallow and apparently silts up steadily. It is mostly surrounded by

dense emergent vegetation including Pond Sedges, Reed Sweet-grass, Iris, Figwort, Angelica, Hemp Agrimony, Willowherb and Thistle with dense shrubs. High canopy, wet, marshy semi-natural woodland, dominated by Alder and Ash extends from the north edge of the lake to the Mimran and beyond. Access to the marshy north side of the Mimran is not permitted and the vegetation is dense and un-disturbed here. Ground flora in open areas includes Mint, Water Forget-me-not and Brooklime, with Dog’s Mercury and Ferns in heavily shaded areas.

Relics of C19th parkland planting include large Beeches on the south east boundary, veteran Horse Chestnuts along the south bank of the lake, Weeping Willow on the north bank and Rhododendron, Black Bamboo and Philadelphus north of the river, Japanese Knotweed and a colossal non-native Beech at the east end of the lake. Dense, tall, old Hollies dominate an area between the lake and site entrance.

Surrounding land. Un-improved wet grassland, grazed to north (including WS 43/039).

Railway Viaduct to the east, roads and urban to the south and rough grassland to the west.

Management. Mainly regular mowing of the grassland and access paths round the lake,

pumping out spreading of silt from the lake bed, pruning or felling of damaged/fallen trees, leaving ecologically valuable dead wood and litter-picking. Overall the site usefully complements the well-grazed wet grassland and marsh across the road in Digswell Meadows South.

Fauna. Rabbits, Moles, Speckled Wood, Comma, Small White butterflies, Common Blue Demoiselle, Muntjac damage to young trees, 2 Swan with cygnet, 2 pr Coot with 8 chicks, pr Mallard with 6 chicks, Chiffchaff, Robin, Tits, Woodpecker, Woodpigeons, Blackbird. A Bat Group survey the previous week recorded 45 Pipistrelle, 55 Serotine & Noctule (?), Daubenton & Leisler’s bats.

JM 15.08.09

Editor’s note.

There is available a long and detailed list of the species recorded which, upon request, I can send to you by e-mail or post.

Work party report to May 2010.

A summary of the past 12 months to May 2010

Having missed a number of work parties over recent months I must open this report with a big thank you to my fellow directors Shirley Henderson and Piers Treacher for their attendance and organisation in my absence.

Can I also thank dog owners who have abided with the signs around the reserve advising on the revised policy of refraining from taking dogs onto the island during the nest season. The Directors have made this change following receipt of increased worldwide studies that show that nesting birds are disturbed by dogs and dog scent.

Work parties as ever have included removing a large amount of litter, often up to 4 large black bin liners worth per month, a number of visitors to the site do take their litter away with them, others however see fit to leave it lying around the site or deposit it by the garage. Thankfully since the erection by the local council of a Dog bin just outside the site we have seen a marked reduction of dog waste, thank you.

Items disposed of include an exhaust system, an old gear box, tyre, road signs and cones and numerous cans, bottles and tennis balls etc and various items that just float down stream from Welwyn and beyond.

Some emergency repairs were necessary to the Garage following some mindless vandalism, this was promptly repaired by a local contractor and the finishing touches applied at the following work party.

Every month the weir is cleared of leaves etc and over recent months a small island has formed down river, this has built up over time from silt and reed growth and now provides a useful area to add further debris.

The recently planted Cricket Bat Willows have been regularly maintained and we have invested in an extension to our current pruning tool for use as the trees grow.

The river has been cleared of tree growth in a number of locations this provides for natural regeneration and prevents the build up of debris which would otherwise become entangled in the often low branches over hanging the river.

A round a dozen large trees received attention from an approved Tree surgeon over the winter months. This work was undertaken following a review of all trees and approval obtained from the local council. A number of trees have been left as standing trunks to provide a long term habitat base for many birds and insects. A further number of small Sycamore saplings were removed before obtaining any height. You may have noticed some serious damage (ring barking) to some oak trees; these are a result of wildlife activity, most likely a combination of deer, squirrel and rabbit. Hopefully these trees will survive but an eye will be kept on them for continued health.

The boundary hedging is still in need of maintenance but to do the job correctly we need the council to carry out some remedial work on a number of their trees, mainly Ash which are shading sections of hedge. Holly has grown up along the boundary in many places and this has been encouraged as a boundary where possible.

The main gate lock looks to be standing the test of time following recent repairs, but if anybody does experience difficulty with their key then do please contact us either on 0845-003-5253, by email info@digswell-lake.org.uk or write to The Hon Membership Secretary Digswell Lake Society C/o 135 Oakdale, Welwyn Garden City, Herts. AL8 7QS.

James Godbold

DIGSWELL LAKE SOCIETY
is a registered charity (No. 296918) and a Company Limited by
Guarantee incorporated in England (No. 2125155)