Talks for Winter 2011_12:
The lost rivers of London; Stanmore Common survey ; Reptiles ; The new Flora of Hertfordshire ; Otters
The lost rivers of London
London has a number of rivers flowing into the Thames both north and south of the river, though this presentation dealt only with those north of the Thames and focussed on the Wlbrook, the Fleet and the Tyburn. While the headwaters are often still above ground, in the suburbs, the City and
Map showing the lost rivers of
Many of the rivers can be traced. The London Topographic Society has published the Agas map and the Copperplate map showing Elizabethan rivers. Street names such as Cow Cross, Town Mill, Fleet Street, Knightsbridge tell of hidden rivers, as do early Ordnance Survey maps before the major development of
Archaeology can also provide clues. For example, excavations keep finding odd little unexpected culverts. There was a boom in rescue archaeology under Professor Miles just after the Second World War during the reconstruction period. In a transect across the River Walbrook, he found the
There is also City mythology, such as the reputed stream under the Bank of England used by bank robbers to enter via the Walbrook culvert. However, this is a myth.
Subsidence also occurs due to lack of maintenance of the culverts. The Walbrook in the City of
The Walbrook probably starts on the fringes of Hackney, from springs at the base of the Hackney Gravels. The Roman riverfront was 60m back from the current riverfront and the Wlbrook approaches from Moorgate Circus and Spitalfields. In 1570, Moorfield, north of Moorgate, was open ground used for drying laundry etc. The Walbrook drains into the City Ditch (alongside the City wall) at All Hallows on the Wall. The Wlbrook had a water mill (probably an undershot mill with a 2-3 feet drop). In the 18th century a culvert was excavated with iron grilles at either end. The City Ditch runs from Moorgate through Bishopsgate and Aldgate to the
At St Margaret’s Lothbury, one corner of the church is collapsing into a Walbrook culvert and St Mildred Poultry is no longer there but a substantial stream was described as going through it in 1860. At Walbrook, the street, excavations in 1956 discovered the
River Holborn (or Fleet)
This river has at least 4 names, the Holborn, the Fleet, the Turnmill Brook and the
Its source is on Hampstead Heath and Highgate, which is the source of a number of rrivers, such as the Westbourne Tyburn and Fleet draining south, tributaries of the River Brent draining north and Hackney Brook and Mosul Brook draining east. Hampstead Heath is capped by Bagshot Sands and water dissolves iron to produce Chalybeate Wells. Springs occur at the junction with the Claygate Beds and drain into Hampstead and Highgate Ponds. The latter was built as part of the late medieval water supply of the City of
In 1800 it flowed down to St Pancras Station and there are paintings of bathers in the Fleet in 1815. It passed by Smithfield Market, where the traders were allowed to draw off water to wash their meat but not to discharge into it (though they often did). It became hemmed in by houses and rapidly became an open sewer. It flowed past the Fleet Prison,
The river Fleet does not enter the
From the Belsize Park area, the River Tyburn crosses the Regent’s Canal in a culvert then into Mayfair where it was called the St Mary bourne or stream to avoid the unsavoury connotations of the name Tyburn, hence with several changes in spelling to Marylebone.
Water from the Tyburn has been taken from the 13th century with conduits into the City of
Stanmore Common Survey and Grant Application
Steve Bolsover, John Dobson & David Bailey
This joint meeting with the Harrow Nature Conservation Forum heard presentations on Stanmore Common, its survey, maintenance and future management.
Steve Bolsover gave an introduction to Stanmore Common, the northernmost of
John Dobson spoke about botanical survey and mapping of the Common in 2010 and specifically on the indicators of ancient woodland. Ramsons occur close to
A number of management issues arise and examples were given from Compartment 13 The Wetwood. Here there is seasonal inundation of the wet woodland habitat, which has particular value for its uniqueness, most of the areas where ponding occurs being old gravel diggings. The summer water table is only inches below the surface and there is a drain but, while this probably drains in from the road, it may drain out and this would need to be examined as part of a water-level management plan (the statutory plan for SSSIs). Characteristic species include velvet bent and creeping jenny and there are roadside flora, such as hawkweeds, decaying timber habitats and mature trees adjacent to Harrow Rugby Club. Brash from clearance at the Rugby Club is a potential problem and fly-tipping from the road is common. Street lighting could also have an adverse impact if it were to be installed. Rabbits occur alongside
Use of global positioning satellites (GPS) enabled the establishment of a database which is geographically referenced (geographical information system) and with imported altitude data enables detailed contour mapping which shows Pynding Mersc as the lowest point at 118m above ordnance datum with the highest point being in the south of the reserve near Warren Lane at 150m. The rise from Pynding Mersc to the
David Bailey spoke briefly on the maintenance work carried out on the reserve, largely by volunteers of all ages, including local community groups and the British Trust for Conservation Volunteers. Scrub clearance is a major task and bracken has to be cut regularly and the brash cleared. On New Heath, they are trying to get saplings up by the roots to keep the heath open rather than having to cut them back every year or so. Brambles are generally left other than ensuring that paths remain open.
Steve Bolsover then spoke about the Heritage Lottery Fund application for restoration work at Bluebell Heath. This area comprises a series of small rides or glades divided by secondary woodland (generally less than 20 years old, which is not rich in ancient woodland indicators, with a small wet-flush area in the extreme west. The intention is to clear this secondary woodland and the more mature woodland between Bluebell Heath and New Heath to create a continuous stretch of open heathland which could then be maintained by council mowing. Stanmore Common lost its SSSI status because the areas of acid grassland were too small to maintain the insect population and this restoration would give space for that population to spread over the wider area. A Heritage Lottery Fund grant of £40,000 is being sought to clear the woodland and scrape soil and then scatter material from nearby to enable regeneration of the open heathland. A pre-application has been submitted and the support of Harrow Natural History Society was sought for the full application and to help create a management plan for Stanmore Common to replace the last management plan of 1999. All present agreed that the Society should support this application.
Reptiles and amphibians (and other wildlife) of
This profusely illustrated talk covered the reptiles and amphibians of two areas in the southern
Compared to the UK’s 3 snakes, 3, lizards, 3 frogs, 2 toads and 3 newts, South Carolina has 39 snakes, 12 lizards, 16 tortoises and terrapins (+ 5 marine turtles), 1 alligator, 31 frogs and toads and 35 salamanders and newts.
The holiday was based at Hilton Head Island, a sand-spit island at the southern end of the
A male southern toad was seen in the local shopping mall and a green anole displaying with its dewlap on the roof of a shop. The local beach had sand dunes behind and a disorientated baby terrapin was seen making its way towards the sea. On the golf course, they were shown an alligator den under the bank of the lake for winter hibernation. Birds seen included brown pelicans, northern cardinal, eastern blue bird, little blue heron, pied billed grebe, red-bellied woodpecker, brown thrasher, northern mocking bird, great egret, white-throated sparrow, yellow-rumped warbler, brown-headed cowbirds, blue jay and grackle. A south-eastern 5-lined skink was seen hiding in the leaf litter, presumably to escape cats, which predate them, though the cat almost comes off worst as they are toxic to them. Spanish moss was abundant on trees.
On the way to the Tilman Sands Heritage Preserve, a black vulture was seen circling over Walmart and there was a boat-tailed grackle in the car park. The reserve includes swamp cypress with its breathing roots. A
The Gopher Tortoise Reserve is a dry area with very sandy soil. The gopher tortoise digs long tunnels up to 40 feet down, which are used by many other animals as refuges. In the harbour were laughing gulls, brown pelicans and a double-crested cormorant. A dolphin-watching trip out to sea was successful.
At the Sea Pines Nature Reserve, a green tree frog and a southern leopard frog were seen as well as a ribbon snake eating a small frog. Other species included red-bellied woodpecker, white ibis, grey catbird and grey squirrel (in its natural habitat). The Sugar Cane Reserve had numerous mosquito fish, a common snapping turtle, a banded water snake, squirrel tree frog and a juvenile cottonmouth (water moccasin). ~There were ant lion pits in the car park.
This holiday was at Big Canoe, Georgia, a gated community for residents and visitors on the edge of the Blue Ridge Mountains in hilly mountainous terrain, a very different habitat from that on
Birds seen included pileated woodpecker, red-headed woodpecker,
At the Amicolola Falls Park there was a reptile display in the information centre, which included eastern box turtle, copperhead (a pit viper), timber rattlesnake, eastern garter snake, corn snake and northern water snake. In the park they saw tiger beetles, eastern tiger swallowtail and black swallowtail butterflies, eastern fence lizard, 5-lined skink, bullfrog and bullfrog tadpoles and a groundhog or woodchuck. Birds included Blackburnian warbler, cedar waxwings, tree swallow, eastern bluebird, killdeer, broad-winged hawk and mourning dove. Climbing up alongside the waterfall it was surprising to see a northern water snake on the rocks well away from the water, which turned out to be hunting Ocoee salamanders on the edge of the waterfall. There was also a southern ring-necked snake.
The Dahlonega gold mine is now owned by the state as a tourist attraction and it was still early enough in the year for there to be bats hibernating inside.
At Toad’s Pond there was a stump which had been taken down by beavers and green frog tadpoles, northern cricket frog, spring peeper (a tree frog) northern banded water snake and black racer snake. Birds included northern flicker (a woodpecker), downy woodpecker,
The new Flora of Hertfordshire
This presentation described the new Flora of Hertfordshire published in December 2009 by the Hertfordshire Natural History Society and how it relates to what we’ve known for a long time. The previous flora by John Dony was published by the
What does it contain?
The Flora contains accounts of all 1,969 species 155 sub-species and 166 hybrids recorded in Hertfordshire, including habitat, occurrence and a detailed record of less common species. There are 882 current distribution maps for the more frequent species from the survey carried out from 1987 to 2005. There are also statistics on occurrences and changes in status of species since the last full survey for the Dony flora.
The Introduction describes the flora survey and how it was carried out. The policy has been to record every locality that has ever been in Hertfordshire since 1860, even though it may be in a different county now. It includes the Botanical Society of the British Isles (BSBI) baseline surveys across the country using selected squares as samples.
There is a brief history of botanical recording in Hertfordshire with background information on Hertfordshire geology, hydrology, soils and climate with soil and geology maps and a summary of Hertfordshire landscape history relevant to its flora. The habitats (communities) of Hertfordshire’s wild plants are described. There is a brief analysis of changes in flora over the last 40 or more years. There is a study of the effects of alien plants in Hertfordshire.
A photo gallery of botanical localities shows them as they were when the flora was surveyed and photos of rare or uncommon plants were taken when they were recorded and contributed by a number of different botanists. Line drawings by local naturalist Andrew Harris are included. There is a Hertfordshire “Red list” of threatened species and a gazetteer of plant localities accessible to the public.
The Foreword is written by Richard Mabey, who contributed to the recording around Tring. Many people (over 250) contributed in many different ways.
The first ever plant record in Hertfordshire was of Spindle between Ware and Barkway by Gerard in 1538. History of the landscape is shown by early records such as Bog orchid between Hatfield and
Other information comes from maps such as the Common at Northaw in 1766, clearly shown as heathland (there were over 10,000 acres of heathland from
Interesting survivors include Snake’s head fritillaries at Northaw, first reported by Joseph Sabine in 1815. They had not been recorded there since but 46 plants were found during the latest survey.
R.H. Webb and W.H. Coleman published Flora Hertfordiensis in 1849, the main author being Coleman, a 20-year old teacher at the
A.R. Pryor’s A flora of Hertfordshire was published in 1887. In the meantime, there had been massive changes to the landscape with drainage roads, railways, housing estates and enclosures. Other notable surveys were by Joseph Pollard of Highdown (1827-1909) whose collection is at the
How was the current survey done?
The survey started from the North Hertfordshire Museum Natural History Department at Baldock in 1987 and moved to the Hertfordshire Biological Records Centre at
The record of Marsh violet at Patmore Heath is one of the very few sites in
Unsolved mysteries include whether Mezereon is native at Great Gaddesden, where it was last recorded in the 1880s. Just how rare is Mousetail? It occurs in areas which are wet and muddy in winter and dry out in the summer and it can lie dormant for decades until the right conditions occur, eg it was recorded in
Totally new finds include Hybrid Woolly and Field thistle at Danesbury, Wewyn in 2007, which was a new record for the
Plants possibly thought to have died out during the survey include Spotted cat’s ear at Therfield Heath, Marsh fragrant orchid at Moor Hall Meadow and Field fleawort at Telegraph Hill. Plants that may have responded to conservation include Crested cow wheat at Nuthampstead, Corn cleavers at Rothamsted (the only locality in
Some rampant weeds include Buddleia, which was hardly mentioned in Dony’s day, Green alkanet, Prickly lettuce (an interesting rare plant in the 19th century which responds to increased nitrogen levels from car exhausts on road banks) and Fleabanes.
So what happens next?
Monitoring of scarce plants is in place with a selected group of plants being checked every year for the BSBI’s monitoring and atlases of change in the British flora 1987-2004. Botanists in Heretfordshire are working with new taxonomies eg the Crack willow is now considered to be a hybrid between a Caucasian species and White willow. They are also assisting Mark Spenser (Natural History Museum) to re-survey the flora of
New plants continue to be found. 27 new species, sub-species or hybrids were recorded by the end of 2010 and another 22 new plants by October 2011. Habitat loss or damage continues, climate change effects are increasing and there is always the unexpected.
Dr Daniel Allen
Described in the Guildford Times headline as having a “Childhood otter obsession led to new book” (ALLEN, Daniel, 2010. Otter. London, Reaktion Books Ltd 183pp. ISBN978 1 86189 767 1), Daniel Allen has been fascinated by otters since watching the film Tarka the otter as a child. He did his PhD on social practices of otter hunting, which was banned in 1978. One of his aims is to educate and entertain people about otters to make people aware of otters and their conservation needs.
It has been reported that the clean-up of
There are 13 species of otter around the world:
The fur trade is still massive in some parts of the world. For example, 778 otter skins were confiscated in
The films Tarka the otter and Ring of bright water had major influence on attitudes to otters. In 1960, ring of bright water sold 1 million copies in the
There are estimated to be about 10,295 otters in the
Otters are largely nocturnal so they are difficult to spot and spraints, tracks and holts give an indication of numbers but because they are wide-ranging it is difficult to tell whether signs are from multiple otters or a single otter in different parts of its range. What is known is that increase in the number of otters leads to a reduction in the mink population.