Talks Summer 2011: Water voles ; Cornish Coastal Path ; National and Local Birds ; Ruislip Woods; Northumberland ;Ferns and gardens:how ferns found their way into the garden.
This page provides a synopsis of the recent talks given to the Harrow Natural History Society by visiting speakers.
Home Page Our next talk will be given in September by Mike Howgate on the Hidden Rivers of London. See home page for details.
December 2010: Water voles
Wetlands for Water Voles & People Project
Ali Hauser
This presentation gave an introduction to the £0.5 million Wetlands for water voles and people project. This is an active partnership between the Hertfordshire and Middlesex Wildlife Trust, the Environment Agency, British Waterways, Hertfordshire Biological Records Centre, Thames Water and the
The Hertfordshire and Middlesex Wildlife Trust (www.wildlifetrust.org.uk/herts) is one of 47 trusts in
Introduction to the ecology of the water vole.

It enters the water with a plop, which acts as a warning to other voles. It sits high out of the water and produces a big wake. It is not properly adapted to a riparian lifestyle, not having webbed feet and its fur gets water logged when remaining submerged for a long time. However they are excellent swimmers.
Water voles range across much of

Water voles are often found making round burrows about 4-8cm in diameter along the tops and sides of banks. These provide protection and form a network, which is added to, with different levels to avoid flooding. In areas with no bank side, such as reed beds, water voles make nests, which are hard to see and often ruined if found
Gestation is 21 days, with up to 8 young per litter and 2-5 litters per year. Young are weaned at two weeks and independent by 6 weeks. Young born before June can breed that year.
Water voles are expected to live up to three winters, though the majority rarely live past two. Over-winter mortality can be as high as 70%, especially with dispersing juveniles seeking to establish territories. It is mainly female water voles that are territorial.
Water voles are known to eat 227 different species. In winter they can eat roots, rhizomes, bark and bulbs etc. Water voles consume 80% of their body weight daily
How to spot a water vole.

Burrow & lawn Feeding station Remnants Water vole Rat
Burrows are a good sign but they may not be occupied. They are often characterised by a neatly cropped ‘lawn’ around the entrance to the burrow. Tracks may also be a good indicator but are not totally reliable. Droppings are distinctive 8-12mm long cylindrical pellets rounded at both ends, easily distinguishable from the vile-smelling rat droppings with their pointed end. Most distinctive is the remains at feeding stations, since water voles bite through reeds, sedges etc at a constant 45o angle.
The decline of water voles.
In the UK the population had fallen from its estimated pre-1960 level of around 8 million to 2.3 million in 1990 and 354,000 in 1998 (a 90-95% loss). There are no water voles in
Anti-predator behaviour includes running to their tunnel systems- some entrances can be underwater, hiding in the vegetation or diving under the water and kicking up a screen of sediment. These defences have been sufficient to ensure the survival of the species since the last ice age.
Threats to water voles and their habitats include overgrazing, ploughing close to water, domestic cats, dredging, pollution, loss of natural banks and water abstraction and drought
The most significant threat, however, is that from American mink, which have bred and extended their range from releases and escapees from mink farms, the last of which closed in 2003. There are an estimated 110,000 wild mink wreaking havoc with indigenous species. Water voles are projected to be facing extinction by 2012. Water voles’ defences are not good enough to survive mink predation, as mink can enter their burrows. Dramatic declines can result from over-winter predation. The main predation pressure on a local water vole colony arises when a female mink is nursing her young and needs to provision the litter with fresh meat. Dispersing mink can cover 20-40km, thus nearly all extant water vole populations face a high likelihood of mink eventually dispersing into their habitat. Females can hunt up to 1.5 km up and down the river from the den. This strategy will locate all water vole colonies in that area but will also wipe out the whole colony because she hunts nightly. Mink are efficient hunters of water vole and will preferentially take them over other species.
American mink
Water voles used to be widespread throughout Hertfordshire. The decline of the water vole over the last 15 years or so is one of the most catastrophic declines of a species ever known in the
Wetlands for Water Voles and People Project.
This project aims to:
• conserve and increase water vole populations, increasing the number and range of water voles in Hertfordshire and the
• increase local community participation in water vole recovery and wetland protection; and
• improve public access to and understanding of wetland habitats.
It involves determining the presence of mink through 137 raft or trap sites across Hertfordshire. As a result, 268 mink have been caught and despatched since December 2004.
The project also involves survey training to identify the presence of water voles. 30 people have been trained and survey days carried out. Events are held to raise awareness and habitat works are carried out to improve the situation for water voles. Hertfordshire has 5 wetland havens at Purwell Ninesprings, Tewinbury, Silvermeade, Frogmore Meadows and
How you can help
The project would welcome help from the public at large:
• Tell us about any sightings of water voles or their field signs;
• Join a local survey group or training session to learn to survey for water voles; and
• Support the Wildlife Trust!
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January 2011: Cornish Coastal Path
The Cornish coastal footpath.
Ivan French
Established in 1929, the south-west coastal footpath was one of the earliest long-distance footpaths. It extends for 500 miles from Poole along the coasts of Dorset, south Devon,
This presentation described a walk undertaken by Ivan and his wife from
The only deadline they had to meet was the ferry across the Helford River to Helford to avoid adding 10 miles to what was already a 10-mile day. This was met but the absence of bed & breakfast accommodation in Helford meant another 5-6 miles to a farm recommended by the Post mistress.
The walk included passing through both abandoned and active coastal quarries, visiting St Michael’s Mount, seeing the spectacular Minack Theatre and wandering around the Levant mine in
The presentation was beautifully illustrated with numerous slides.
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February 2011: National and Local Birds
National and Local Birds
Denis Bristow (RSPB Pinner)
This presentation covered the history and work of the Royal Society for the Protection of Birds (RSPB),
The aims of the RSPB are to:
It is one of the oldest wildlife charities, starting in 1889 in Didsbury,
In 1947, bird watchers on the east coast found avocets, which had long been absent from
The RSPB has 118 reserves covering more than 76,000 hectares and they receive over 1 million visitors per year. (These figures are somewhat dated as there are now 160 or so reserves).
Ospreys at Loch Garten in
In the 1950s/1960s, the pigeon racing fraternity complained that the increase in the numbers of peregrine falcons was resulting in increasing deaths of their pigeons. The British Trust for Ornithology and the RSPB carried out a special investigation, which found that peregrine falcons were in fact in dire straits because dieldrin, ddt and other agricultural chemicals were being ingested by their prey and building up in the falcons, leading to the production of thin-shelled eggs that could not bear the weight of the incubating parent bird. Many of these agricultural chemicals have now been banned and the peregrine falcon population is now on the increase, even breeding in town centres (eg at the South Bank Power Station).
The red kite was a widespread scavenger on middens but it too suffered badly from persecution and by the late 1920s there were only 8 or 9 in
The corncrake was a common bird of farmland but changes in agricultural practices led to its decline. Successful appeals by the RSPB in the northern isles for crofters to leave fields until grass grows to a reasonable height are now leading to numbers increasing.
International projects include a large number in Europe and Africa (the migration routes of summer visitors) with some in
There are about 29 species of albatross and many are suffering as a result of long-line fishing (and trawling) because they see the fish on hooks and are themselves caught on the hooks and drowned. Modern techniques using streamers to deflect the birds away from the hooks cut the losses considerably and fishermen in several areas have been persuaded to use these techniques.
The presentation ended with slides of a number of water birds, including:
The presentation ended with a plea to help protect our heritage of birds by:
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March 2011: Ruislip Woods
Ruislip Woods as a National Nature Reserve
Colin Bowlt
Ruislip Woods comprises Park Wood, Copse Wood, Mad Bess Wood and latterly Bayhurst Wood. It is the largest area of ancient oak/hornbeam coppice woodland in South east England.
There is evidence of continuous woodland cover dating back almost three thousand years.
Recently a flint arrow head was found together with a bronze pin which would have been used to attach it to the shaft. This find led to an excavation which revealed charcoal made at some time during the Bronze Age about 700 BC from fourteen different tree types.
Reference is made in the Domesday Book of 1186 of the woods within the Manor of Ruislip being used for firewood, timber and pannage for pigs. Within Park Wood there still exists the earthwork boundary dividing the woods between two separate landowners both Norman French convents. There is an important earthwork still to be seen as a bank and ditch which divided off a section of the woods for one of England’s first deer parks.
The tree flora consists amongst other things of oak, hornbeam, beech, woodland hawthorn and wild service. The latter two are ancient woodland indicators. Ground flora awi species include bluebells, wood anemone and yellow archangel.
Current management action involves the reintroduction of hornbeam coppice on a 15 year cycle which was restarted in the 1980s. Cattle are used to graze the grass and keep the scrub at bay although they also take all ground flora. Subsequent to them depleting the heath spotted orchids, the area has been enclosed to allow regeneration. Scrub clearance is ongoing and allows the opening up of the traditional waste land areas. The paths through the woods are heavily used and become very muddy and spread laterally. Some board walks have been laid to prevent this degradation but it is an expensive solution.
English bluebells
Yellow archangel
April 2011: Northumberland
Northumberland and the Borders
Dr David Brook OBE
This paper presents a tour from Berwick-upon-Tweed to the lower
Historic Berwick upon Tweed is the most northerly town on the
Berwick was a Royal Burgh of Scotland in 1120 and during the many centuries of border warfare changed hands no fewer than 14 times, the last being in 1482. It was part of the ransom paid by the captured William the Lion of Scotland to Henry II in 1147. It was sold to the Scots by Richard I to get money for his Crusade. It was destroyed in 1216 by King John in person. When William Wallace (Braveheart) was executed in 1305 in
Berwick had a special status as a free borough and was mentioned separately in Acts of Parliament. So far as records had shown, it was still at war with
The Guildhall, built in the 1750s, is possibly the most handsome building, facing and dominating broad Marygate. Of rich brown stone in a Classical design, it has a grand portico with giant Tuscan columns and a tall spire. The bells ring for
Berwick’s well-worn appearance seems to suit its historical role as a buffer town. It was an important trading centre and international port. The town captured or sacked 13 times before 1482, when it was finally made English. Until 1746
The Barracks were built between 1717 and 1721 in response to town objections to billeting soldiers in public houses. Their design is attributed to Vanbrugh. They contain the museum of the King’s Own Scottish Borderers, which is open to the public.
Berwick has had two sets of protecting walls. The first walls were completed in the reign of Edward II and little is left of them. The town was then fortified by Elizabeth I, starting in 1558, on the new Italian design with great emphasis on effective use of artillery. The walls cost a staggering £128,648 and were the most expensive undertaking of the Elizabethan period. They are the only example of this style in
Three bridges span the River
The red sandstone
The
The
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Robert Stephenson’s Royal Border Bridge, Berwick-upon-Tweed |
The |
Himalayan Balsam on the banks of the River Tweed |
Paxton House, one of the finest Palladian country houses in
The
From the A1 to just upstream of Coldstream, the Tweed forms the border between
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Red Squirrel at Paxton House, Berwick-upon-Tweed |
Red Squirrel at Paxton House, Berwick-upon-Tweed |
Pheasant at Hirsel Country park, Coldstream |
The Hirsel Country Park comprises farmland and areas of forestry with a designed landscape around the house and the River Leet. The parkland is 19th-century in character but was laid out originally in the late 18th century and some tree planting from this period survives. The structure of the 18th-century walled garden also survives. This estate has been the seat of the Earls of Home since the early 17th century. Walks around the country park take in a late 18th-century lake, which is home to geese, swans, moorhens, coots, ducks and grebes, and follow winding paths through a 19th-century woodland garden with rhododendrons. Ornamental gardens around the house date to the mid-20th century.
The Carboniferous rocks of much of the north Northumberland coast consist mainly s of limestones, sandstones and shales with, in places, a few coal seams. 295 million years ago, these rocks were folded and fractured and were intruded by large quantities of dolerite (the Whin Sill). More recent rocks, which form substantial parts of the undulating landscape of the coastal plain include glacial till (with boulders of rocks from the cheviots and from
Holy Island or Lindisfarne, is one of the most important sites in the history Christianity in
The 6th and 7th centuries were a period of outstanding brilliance both for Holy Island and the whole of
In 793, the first Vikings came in their longboats to burn, steal and kill. Time after time they returned to ravage the holy places, and in 875 the monks were forced to flee in terror, bearing their Gospels, the body of St Cuthbert and other precious relics. For 200 years monastery remained uninhabited.
In 1082 the Benedictines revived the community, renaming Lindisfarne '
After the union of
The route across the
The Village of Bamburgh is the ancient capital of
Ida, the Saxon monarch and founder of the dynasty of
King Oswald, a convert to Christianity, spent some of his early years in exile on the Scottish
In later centuries it fell into disrepair, Lord Crewe, the last of the Prince Bishops of
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Lesser Black-backed Gull, Seahouses |
Immature Herring Gull, Seahouses |
Herring Gulls, Seahouses |
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Redshank, Seahouses |
Curlew, Seahouses |
Grey Heron, Seahouses |
The
The Farne Islands are a group of low-lying islands approximately 3 miles off the coast of
There are an estimated 3,000 to 4,000 Grey seals on Farne. Pups are born in November and gain up to two lb. a day in weight. After only 6 to 8 weeks parents leave the pups to fend for themselves.
There are 40,000 pairs of Guillemots on
50,000 pairs of Atlantic Puffins nest in burrows excavated in the peaty soil and lay a single whitish egg. Puffins nest just beyond arms reach, numbers peaking with last year’s juveniles in mid July- most puffins leave the
Up to 500 pairs of Eider duck live off crab and shellfish. Their nest is lined with down and they lay up to 10 eggs. They are the earliest breeders with chicks often leaving the
Kittiwakes build a nest of seaweed and grass, clinging to the cliffs. Four species of tern- common, arctic, sandwich and a few roseate breed on the
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Grey seals on the Farne Islands |
The Longstone Light, |
Grey Seals on the Farne |
The Longstone Light was built 1825 to 1826. Since 1980 it has been unmanned and operates automatically. The lighthouse is 4 nautical miles from harbour, flashing once every 20 sec. day and night.
Inner Farne has its
10 years ago, The
July 2011: Ferns and gardens:how ferns found their way into the garden.
Howard Matthews
The speaker has always been more interested in botany and ecology than gardening. Ferns are not bred like flowers, which have been subject to years of selective breeding and hybridisation. The ferns in the garden are the original species.
Magic and folklore
Ferns were not grown in medieval gardens. Indeed mystery and folklore grew up around them from medieval times. For example, moonwort was long associated with things magical and was believed to have the power to open locks, unshoe horses and change metal. Male fern was seen as essential in a love potion. Pagan ceremonies developed around ferns and “fern seed” was believed to have magical properties, giving invisibility, as mentioned in Shakespeare’s King Henry V. It was claimed that fern had a blue flower at midnight on midsummer eve, with the seeds appearing moments after – if collected they gave the power to discover hidden treasure, while to drink the sap conferred perpetual youth. In the 17th century, it was believed that setting growing bracken on fire would produce rain and the High Sheriff of Stafford was asked to prevent this during a visit by King Charles I to ensure fair weather during the visit.
Herbal uses
Renaaissance gardens were very formal and had no ferns but ferns had many herbal uses, including male fern, lady fern, royal fern, hart’s tongue, maidenhair fern, polypody, rustyback and wall rue. Infusions were made from ferns fr a wide number of ills. Adder’s tongue was regarded as a cure for tumours, to bite on a young crozier in spring was the rural remedy for toothache and extracts from rhizomes of bracken and male fern were used to expel intestinal worms.
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Fern gatherer |
Wardian Case |
Fern gatherer 1877 |
In general, the ferns were not grown for herbal purposes but simply gathered from the wild as required. However a list headed Additional commonly grown plants listed by Jon Gardener circa 1350 includes polypody as a “primarily medicinal herb. Around 1525, Thomas Fromond, a landowner from Surrey, compiled a list of Herbs necessary for a garden, in which herbs for pottage included hart’s tongue and in about 1596 John Gerrard of Gerrard’s herbal is said to have grown black spleenwort, male fern, lady fern, adder’s tongue, hart’s tongue and wall rue.
Other uses
Bracken was used for bedding for both humans and animals, for insulation under floors and in walls and as thatch where few other materials were available. It was also used as packaging material for produce such as fresh fruit or for transporting Welsh slate. When burnt, bracken was used as top dressing for peatlands because of its high potash content and later it was burnt to produce potash for glass-making and for soap-making..
Fern collections
There were few fern collections in
By the 1770s, collecting ferns was more popular and considered more important botanically. Between 1770 and 1790, 68 species were brought to
In 1794, John Lindsay, a British surgeon in
The 19th century saw a steady inflow of new arrivals to
Ferns become popular
By the time of the accession of Queen
Knowledge of the propagation of ferns grew slowly, with propagation on a large scale first carried out successfully at
The Wardian Case
The invention of the Wardian Case represented a significant advance in maintaining ferns once they had been propagated. This closely glazed case (an ornate miniature greenhouse on legs) was invented by Nathanial Ward to house a hawk moth chrysalis but he noticed that spores of male fern germinated within the case and flourished in the humid atmosphere so he then experimented with ferns. Previous efforts to cultivate ferns had been unsuccessful in the midst of the smoke and fumes of Victorian London. At the same time, new glass-making techniques and the abolition of the glass tax in 1845 meant no home was without a Wardian case. Initially used for expensive, imported exotic species which required heat to survive the British winter, they were soon used also for the cultivation of hardy British ferns, which were available free of charge and needed no artificial heat. Fern collecting became all the rage, especially with the expansion of the railways making more of
Ferneries
From the Wardian Case, it was but a small step to the fernery in a glazed Victorian conservatory alongside the house or in botanical gardens. Examples included a great exhibition of 1866, Brighton Aquarium, Benmore Fernery,
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Edinburgh Botanical Gardens 2007 |
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Ashridge |
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Bench at Ashridge |
Tree ferns
Most of the tree ferns on sale now come from
Fern books and artefacts
In 1837-41, the first of a number of detailed and well illustrated fern books (Shirley Hibberd’s The fern garden) were launched and spurred on the growing band of field botanists. In the mid-1840s, the emphasis changed to fern varieties and cultivation hints. 20 guides were published between 1840 and 1866.
Ferny artefacts included benches with fern backs at the
Fern collecting
Fern collecting became a profitable sideline and even normal species were collected by the “spivs” of the day who invaded ferny areas and dug up every fern they found. In 1896, The Gardener’s Chronicle reported that two men from
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Royal fern |
Oblong woodsia |
Hard ferns |
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Hart’s tongue |
Male fern |
Polypody |
The effects of this collecting were significant. The royal fern suffered greatly and it has disappeared completely or become very rare at many of its old haunts where it had been common.
Because of publicity giving exact locations of its habitats, the Killarney fern has vanished from practically all of them. It was first discovered in
The small alpine fern Oblong woodsia was almost eradicated by collectors. In the
The emphasis changed from collecting in the wild to commercial suppliers, such as the W & J Birkenhead Nursery. Catalogues offered over 1,000 species and varieties and one offered 50 varieties of hart’s tongue.
Fern varieties
Variation is caused by genetic mutation, resulting in all or most of the leaves having a peculiar feature. Some variants breed true 100% of the time, while others produce a mixture with wide variation, with only 5 or 10% having the desired form. A limited number of species produce variants, particularly lady fern (more than 300 forms named from it), hart’s tongue and soft shield fern. There is a remarkable abundance of fern variations in
Exotic ferns
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Ostrich fern |
Sensitive fern |
Dryopteris lepidopoda |
A common exotic fern is the Ostrich fern, native to central and northern Europe and North America but not to the
Modern production
Modern production is by in vitro reproduction, taking bits of tissue and putting them in sterile jelly, as practised at a very large scale in
Ferns today
The fern craze continueduntil the early 20th century and was really finished by the Foirst World War, when garden staff and knowledge were lost, large estates broken up and ferneries became disused.
Rock gardens, in which ferns were included were fashionable in the 1920s and after the Second World War there was a rediscovery of the countryside. Bottle gardens were in voguein the 1960s and 1970s and tree ferns became popular in the 1990s. Since then a number of Victorian and Edwardian ferneries began to be restored and there have been new constructions such as the Princess of Wales Conservatory at Kew and the Eden Project biomes in