The Ecology of The Bourne
1. Since its inception in 2002 The Bourne Conservation Group has steadily built up its knowledge of
the natural environment of the area and is therefore well placed to provide a current snapshot. In doing
so, it would be an easy matter to provide just a list of known flora and fauna but this might fail to give
an in-depth picture. This paper will therefore consider the ecology of the area so as to relate the
species list to the local geology, geography, climate and historical factors that have been influential. A
pictorial record is included to give a flavour of the local habitats and wildlife.
The Location
2. In referring to The Bourne it is always difficult to know precisely which area of ground is covered.
Is it for example The Bourne Ward or the parish of St Thomas-on-The Bourne? These boundaries are
of course entirely arbitrary in terms of the natural world and, to build up a meaningful picture of this
diverse area, the paper draws upon data and examples from both within and around its periphery
without straying outside an area of about 5 square miles.
3. The Bourne is a hilly, well wooded suburb of Farnham and, in terms of greenspace, provides an
important buffer or transitional zone between the much more densely populated urban area of central
Farnham and the heathlands to the south. In the west it merges into the similar semi-rural areas of
Shortheath and Boundstone and in the east there is a clearly defined boundary with the river Wey
corridor. Thus, in close proximity, there is a range of wildlife habitats associated with urban areas,
woodland, heathland and the river Wey (a designated chalk stream) which together contribute to the
distinctive nature of the area. This is underlined by:
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The presence of two SSSIs : Moor Park just across the Wey, and Gong Hill
The southern part of the area lying within the Surrey Hills AONB
Recognition in Waverley planning policies that much of the area warrants protection by giving
it either Conservation Area or Area of Special Environmental Quality status
4. Situated at the western end of the Weald, the underlying geology is predominantly the Lower
Greensand (Folkestone Beds) overlaid by gravels deposited during the ice age. There are outcrops of
Gault Clay to the southwest and west, and Alluvium along the Wey and Bourne valleys. In general the
area is characterised by poor, acidic soils which originally supported natural heathland vegetation of
heather and gorse with scattered trees as seen today at Frensham and Thursley Commons. There are
minor differences caused by the presence of the gravels and the clay and it is likely that in-depth
surveys would show how these are reflected in the detailed ecology.
Historical Background
5. The Wey valley west of Farnham and the steeply incised valley of The Bourne stream and, to a
lesser extent, the Frensham Vale stream define the grain of the land from SW to NE. Along the north
slopes of The Bourne valley, exposures of Red Farnham Gravels were quarried at the end of the
nineteenth century. The resulting gravel pits were the source of a rich assortment of Mesolithic and
Neolithic artefacts, many of which are exhibited in the Farnham Museum. Some of the sites, for
example the Old Public Quarries along Aveley Lane are still visible today providing glimpses of the
original vegetation but largely and overrun with trees and an under-storey of laurel and holly which
does at least provide shelter for some wildlife.
6. The sandy and rather acidic soil is relatively unproductive and in the past mainly supported only
sparse grazing and subsistence agriculture. This was not the case closer to Farnham where the
underlying geology is more complicated. There, the combination of the Gault Clay and Upper
Greensand gave rise to richer loams ideal for hops. These became a staple crop over a long period,
contributing to the prosperity of the town. There were scattered hop fields (or gardens) along The
Bourne Stream but the small farmers and labourers who had established themselves on plots of land
there often made a living by working in the larger hopfields along the Wey valley. With the passing of
the Enclosure Act in 1836, freeholders had land allotted to them. This was of little value for
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cultivation and so they planted it with Scots Pines and Sweet Chestnuts to generate poles for the hop
fields. A few of the humble cottages from those days still remain such as “Little Willows” by the
stream at the foot of Old Church Lane which is said to date from the mid 18th century. The fascinating
concentration of footpaths along The Bourne valley is also a relic of that era which today provides an
important network of corridors for both residents and wildlife. Commercial hop growing gradually
faded out and finally finished in the 1970s but the plants are still encountered from time to time, for
example in the Middle Bourne Lane Community Wildlife Garden. The life-styles of the early
inhabitants were recorded in the writings of William Cobbett, when he described growing up near The
Bourne Stream in the early 1800s, and later by George Sturt who described the social transitions that
occurred following the Enclosure Act and the arrival of the railway at Farnham in 1848. At that point
the area began to change significantly.
7. When the first parish church was built in 1861, the area was still predominantly open heathland
fringed by hopfields with few trees. Left to natural processes, there is a transition of heathland into
woodland and so some trees are always a normal part of heathland. Thus there are many veteran trees
throughout the The Bourne area with many species represented but with oak and birch prominent as
they do well on the acidic soils. There is, for example, a large pedunculate oak in the corner of the
garden of George Sturt’s house in Old Church Lane. There are also five sites in the wider area which
appear in Natural England’s Ancient Woodland Inventory:
Vanners Copse
Moor Park Wood
Monks Wood
Edgeborough Wood
Black Lane Wood
8. This means these sites have been wooded at least since 1600. However, the current wooded
character of the area has mainly developed over the last 150 years. To some extent this seems to have
been quite deliberate. Some trees are well documented such as the yews and limes in the Old
Churchyard planted by a benefactor in 1863 to celebrate the wedding of the Prince of Wales, who later
became Edward VII, or the avenue of Douglas Firs and Sweet Chestnuts leading to Falkner’s Lodge
Hill House dating from 1903. The predominant tree species is probably the Scots Pine the origins of
which are mentioned above; the RSPB Farnham Heath site was a commercial pine wood until
clearance started in 2004. The valleys are now very heavily wooded and this affects the wildlife.
Despite their seasonal flows, they are important green corridors for birds, bats and other woodland
species.
9. The original parish served just 600 parishioners, but by the beginning of the 20th century the
population had grown considerably, and so the present church was built on the site of one of the gravel
pits. This expansion of the population was partly the result of the building of many large Edwardian
houses. It is these houses with their extensive gardens that, along with the old quarry sites and patches
of public woodland (some of which were donated to the town), now contribute much to the present
character of the area and to linking the key centres of biodiversity that surround southern Farnham.
The role of this green buffer zone is likely to become progressively more important as the impact of
climate changes begin to kick in.
Biodiversity of The Bourne
10. The encouragement of biodiversity is a principal objective of conservation in the UK. The Bourne
is already strong in this respect but it has nevertheless, like other areas in the south, lost the species
which once must have inhabited the local heathland. Hence much attention is now given to the
preservation and protection of heathland and the species it supports, some of which are rare or
endangered. Because of the way it has evolved it is not surprising that some of these have managed to
survive in The Bourne including Sand Lizards (especially in the Gong Hill SSSI) and Woodlarks. The
RSPBs heathland restoration at Farnham Heath is designed to further support these species and the
omens for the success of this project are good (see below). The Bourne is within the 5km protection
zone of the Thames Basin Heaths and is likely to also be in the similar zone surrounding the Wealden
Heaths. This emphasises the function of the area in providing linkage to help maintain sustainable
wildlife populations.
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11. Birds. The Bourne Conservation Group (BCG) conducted an extensive survey of birds as part of
Surrey’s Wildlife Warden Pilot Scheme in 2005. 29 common birds were sighted frequently and
another 20 occasionally. The top ten sightings were exactly the same as the British Trust for
Ornithology’s national survey the previous year (albeit in a different order):
Blue Tit
Wood Pigeon
Robin
Great Tit
Dunnock
Greenfinch
Blackbird
Chaffinch
Magpie
Collared Dove
12. Starling, House Sparrow, Song Thrush and Cuckoo were also recorded but outside the top 10.
These four are designated priority species in the National Biological Action Plan (BAP). This situation
will have changed slightly in the interim. An interesting bird, present but not often seen, is the
Goldcrest which feeds on tiny insects commonly found in the tops of pine trees which, as previously
noted, are common in the area.
13. On Farnham Heath in July 2009 it is reported that there are seven pairs of Tree Pipits and four
Nightjars along with increased numbers of Grayling Butterflies and Sand Lizards. The Tree Pipit and
Woodlark are designated priority species as is the Sand Lizard. (Priority species have been identified
in the UK Biological Action Plan (UK BAP) as “under threat” because of their rarity and rate of
decline. There are 59 birds on the list and more than 1000 species overall.)
14. The Bourne is a dry area in summer but at Waverley Abbey, the combination of the river Wey and
the lake give rise to a number of water-loving birds including Kingfisher, Heron, Canada Goose,
Mallard, Teal, Tufted Duck and Swan. Mink is also regularly seen. The return of the Otter is eagerly
awaited and several holts have been prepared by volunteers in anticipation.
15. Mammals. Mammals were also covered in the same BCG survey from which it became apparent
that the most frequently seen are as follows:
Grey squirrel
Fox
Woodmouse
Roe Deer
Bats
Although Badgers did not figure significantly because of their nocturnal habits, they very much like
the local hilly terrain and there are at least 7 setts and may well be double that number. One sett is on
the small Underdown reserve off Sandrock Hill belonging to the Surrey Wildlife Trust. At least one
sett has probably been lost in recent years due to development activities. Larger mammals like badgers
and deer are put under pressure from urban development but the fox, of course, adapts without
difficulty.
16. A survey carried out for the RSPB on their Farnham Heath site at about the same time revealed
much bat activity including:
Common pipistrelle
Soprano pipistrelle
Serotine
Noctule
Myotis/Brown long-eared bat (Virtually impossible to tell apart)
The Soprano Pipistrelle, Noctule and Myotis Bats are all priority species. There are bats in The Bourne
valley and a significant population in the Waverley Abbey area including Natterers, Daubentons and
Long Eared species.
17. Invertebrates, Amphibians and Fish. As the old gravel pits were worked out they filled with
water and for a time there were reports of large numbers of Frogs and Toads occupying some of them.
Both are still present in The Bourne where water is available but we are not aware of large numbers of
Toads returning to their home pool as happens in some places. Sand Lizards have already been
mentioned in connection with the Gong Hill SSSI. They used to be much more widespread in The
Bourne but there habitat has largely disappeared. Slow Worms are doing well and Grass Snakes are
often seen. Both these species as well as the Toad are listed as priority species.
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18. The Wey is an important wildlife habitat, some species having already been mentioned. To these
must be added the native Trout, Eels and other fish along with Water Crowfoot and a range of flies
and other insects. The Moor Park SSSI is based on an Alder Carr, or piece of wetland, rich in plants,
insects, mosses and lichens. This attracts birds including Redpoll, Siskins and Tits feeding on the alder
cones.
19. Other Species. Because of the variety of its flora, The Bourne is extremely rich in the lower
echelons of the food chain. Recent surveys of the Old Churchyard show that it hosts well over 200
species of animals and plants. The full list is available if required. It might be argued that this site is
something of an extreme case because it has lain largely untouched without use of chemicals for many
years. However, it is also a fact that the Community Wildlife Garden in Middle Bourne Lane which
has a less certain history also shows rich biodiversity. In early July 2009, 51 different species of moths
were caught and identified there in a single night. This site is perhaps more nearly akin to some of the
large private gardens in the area which can therefore be expected to show a similar range of species
especially if there is a pond present. Surveys in the Old Churchyard are not yet complete (eg Lichens
have not yet been tackled) and although the figure of 200 species may be taken as a guide for The
Bourne overall, it clearly represent only a subset of the full inventory of local wildlife. One species on
the priority list is the Stag Beetle which seems to be doing rather well with a number of sightings in
2009 especially in the Old Church Lane area.
Summary
20. What comes out of this review is that the physical characteristics and history of The Bourne have
given rise to an unusually diverse range of habitats and the flora and fauna they support. These
include:
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Heathland at Farnham Heath as a result of the RSPBs restoration project. The Heather, Gorse
and groups of trees are increasingly supporting priority species including Sand Lizards,
Woodlarks, Night Jars, Tree Pipits and Grayling Butterflies.
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Mixed woodland with many mature and veteran trees plus five registered areas of ancient
woodland. This supports a whole range of more common species as well as many on the
priority list. They include Fungi, Wildflowers (eg Bluebells), mammals and birds. Judging by
recent surveys at the Old Churchyard (which may be looked upon as a woodland glade) there
is a minimum of 200 species in the area with some doing particularly well including Moths,
Speckled Wood Butterflies, Stag Beetles and Slow Worms.
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The corridor of the river Wey. This supports a min-ecosystem in its own right. In addition to
Brown Trout, typical water birds, mammals including bats, the Moor Park Alder Carr adds a
further dimension with a range of wetland plants and insects.
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Low density townscape broken up by patches of woodland, recreation grounds such as The
Bourne Green, large gardens and a network of streams and footpaths. This provides very
favourable habitats for many wildlife species that are further encouraged by the food provided
either deliberately or accidentally by the human population.
Climate Change
21. It is clear that climate is a major determinant of ecology and the changes that are now
occurring are particularly relevant. There are distinct signs that wildlife is on the move in
response to climate change and its effects on habitats. In very general terms the movement is
from south to north and for this to take place successfully corridors are needed as facilitators.
Barriers formed by towns, cities, motorways, hostile countryside and even the 6ft high fences
increasingly favoured by residents of The Bourne inhibit such movements dependent on
species. Thus greenspace and green corridors in southern England are gradually assuming
even greater significance than in the past.
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22. These are global issues but it is possible that local effects are already evident. Pictures are
included of some examples recorded recently in The Bourne are as follows:
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The Long-winged Conehead was unknown in Surrey pre-1970
There were only two records in Surrey of Roesell’s Bush Cricket before 1970
The Wasp Spider has spread from the Continent in the last 20 years
The Tree Bumblebee has spread from the Continent in the last 10 years.
The Orange Footman Caterpillar found in the Old Churchyard is the only one recently
recorded in Surrey
The rare Dotted Chestnut moth is expanding its range northwards
The Whitepoint Moth photographed in June 2009 is only the tenth record in Surrey.
The Surrey Biodiversity Action Plan
23. Man has played a major part in the evolution of the ecology of the area. Until recently his role has
been careless of the environment and unsurprisingly there have been some casualties along the way,
for example the Great Green Bush Cricket. Until the 1990s there was a thriving colony, one of only
two in Surrey, of this large insect along the south facing slopes of The Bourne valley each side of the
A287 with the greatest concentration near The Fox public house. This has been lost probably due to a
combination of sewer work in the valley, increased building and greatly increased tree cover shading
the sunny slopes.
24. New problems appear all the time in which context must be mentioned the threat currently posed
to native species by aliens that are highly invasive. These include:
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Himalayan Balsam which is rife along the Wey as it was until recently along The Bourne
Stream
Japanese Knotweed at a number of places including The Bourne valley below Redhill House
Gaultheria in the eastern part of The Bourne Woods owned by the Forestry Commission.
To this list can be added the Mink which has accelerated the decline of Water Voles.
25. However, there is now a realisation that our native wildlife must be protected and enhanced.
Flowing from the UK BAP already mentioned is the Surrey Biodiversity Action Plan (Surrey BAP)
which for Urban settings aims to:
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Protect and enhance urban sites which are already known to be important.
Identify other possible key sites, and take measures to protect them.
Promote the creation of new habitats in urban areas, and the linking of habitats through
corridor identification, enhancement and creation.
Help to ensure that new developments produce a demonstrable gain for wildlife.
Increase awareness of the value and significance of urban wildlife and of the role that people
can play to enhance biodiversity.
Create and improve opportunities for organisations and people to take action for wildlife.
Sadly there is little evidence that all of these aims have been taken to heart by the local planning
authority.
26. The Surrey BAP goes on to say:
“The fates of people and wildlife in urban areas are bound together
inextricably. What is needed is an environment in which people and wildlife can flourish. Any
definition of the overall purpose of the Surrey Urban Biodiversity Action Plan must, then, take
account of both people and wildlife and the Plan may be defined as safeguarding and
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enhancing the biodiversity found in the urban areas of Surrey and so improve the quality of
people’s lives through contact with, appreciation of and involvement in nature conservation.
Even if the area possesses few if any rare species or unusual habitats, its real value should not
be evaluated in those specialised terms. Its true value lies in the social, educational and
environmental contribution it makes to the lives of people living in and around about. The
habitats on site offer the urban dwellers opportunities to experience, to learn about and to
appreciate flora and fauna which they might not otherwise encounter.”
The educational potential of the rich variety of habitats in The Bourne is yet to be fully realised.
27. Policy CC8 of the South East Plan states that all Local Authorities should have a Green
Infrastructure (GI) Plan. GI is a network of multifunctional green-spaces within and between cities,
towns and villages. These can include formal parks, gardens, woodlands, green corridors, waterways
and open countryside. GI should contribute to improving sustainable resource management,
biodiversity, landscape, and regional development and promotion. It should have:
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Social benefits through improvements in quality of life and access to open space;
Economic benefits through investment and employment; environmental benefits;
Health benefits by promoting an active lifestyle.
28. The Bourne as a semi-urban environment is already providing these GI functions. However, the
rate at which infilling and garden-grabbing has been developing is threatening the effectiveness of its
contribution to GI. As an example there has been a recent increase in uncontrolled felling of trees on
private property, as a prelude to applying for planning permission for development, and a seeming
reluctance of the local authority to take pre-emptive action to protect local trees and woodland..
Conclusion
29. The landscape, geology, wildlife and history of the The Bourne all contribute to its highly unusual
character. It is important that we protect this special area and prevent further losses to Farnham and
Surrey’s biodiversity. Climate change intensifies the need to preserve the type of wildlife habitats
found here.
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