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HEDGE ASSESSMENT AND
BAT ACTIVITY SURVEY
Brook Farm
Marden
Herefordshire HR1 3ET
Final report 20th August 2013
Survey and reporting: Dr Johnny Birks BSc MCIEEM
NE Bat licence WML-CL18 (v 01/2013)
Checked by: Lisa Kerslake BSc MSc CEnv MCIEEM
Client: S & A Produce Ltd.
© Swift Ecology Ltd
Rose Cottage
Market Square
Kineton
Warwick
CV35 0LP
Tel 01926 642541
Email [email protected]
Website www.swiftecology.co.uk
Printed on recycled paper
Hedge Assessment and Bat Activity Survey SWIFT ECOLOGY
C998 Brook Farm, Marden, Herefordshire 1
CONTENTS
1 SUMMARY ................................................................................................................................... 2
2 INTRODUCTION................................................................................................................................. 3
2.1 BACKGROUND ................................................................................................................................ 3 2.2 ECOLOGICAL CONTEXT ..................................................................................................................... 3
3 METHODS ................................................................................................................................... 4
3.1 HEDGE ASSESSMENT ........................................................................................................................ 4 3.2 BAT ACTIVITY SURVEY ...................................................................................................................... 4 3.3 CONSTRAINTS ................................................................................................................................. 5
4 RESULTS ................................................................................................................................... 6
4.1 HEDGE ASSESSMENT ........................................................................................................................ 6 4.2 BAT ACTIVITY SURVEY ...................................................................................................................... 6
5 EVALUATION ................................................................................................................................... 8
5.1 EVALUATION OF HEDGE AGAINST WILDLIFE SITE CRITERIA ....................................................................... 8 5.2 BATS ............................................................................................................................................. 9
6 RECOMMENDATIONS ................................................................................................................... 11
6.1 PRECAUTIONARY APPROACHES TO DEMOLITION/REMOVAL WORKS ........................................................ 11 6.1.1 Bats ................................................................................................................................. 11 6.1.2 Nesting Birds ................................................................................................................... 11
6.2 HABITAT COMPENSATION AND BIODIVERSITY ENHANCEMENT MEASURES ................................................ 11
7 RELEVANT LITERATURE ................................................................................................................. 13
APPENDIX 1 HABITAT COMPENSATION AND ENHANCEMENT MEASURES.................................. 14
Hedge Assessment and Bat Activity Survey SWIFT ECOLOGY
C998 Brook Farm, Marden, Herefordshire 2
1 SUMMARY
• A section of roadside hedge was assessed for its biodiversity value and a bat
activity survey at dusk was undertaken at Brook Farm, Marden in July 2013.
• This ecological work was required in connection with proposals to remove a
section of the hedge and to demolish or remove some of the buildings with
low bat roosting potential on the site, prior to constructing a new vehicular
access and a new office building.
• The habitats and plant species found in the hedge section are widespread
and common, and its botanical diversity is relatively low. The loss of this
section will have a minor, short-term adverse effect upon biodiversity in the
locality.
• Levels of bat activity on the site were low during the dusk survey, and there
was no evidence of bats making use of the buildings proposed for demolition
or removal.
• This low level of bat activity and the low bat species diversity at the site is
consistent with the relatively poor bat foraging habitat present and the low
bat roosting potential of the buildings on the site.
• The majority of bat activity and the greatest species diversity (albeit both
rather limited) was associated with the southern edge of the site, where a
line of trees provides both foraging habitat and a commuting route. This line
of trees will be removed as part of the proposed development, so there will
be some impact upon bats as a consequence.
• Overall, the proposed changes to the site will have a minor adverse impact
upon bat activity in the locality.
• Any adverse effects will be short-term only, because compensatory habitat
creation will lead to a significant increase in biodiversity on the site; this will
include an increase in the availability of foraging and commuting habitat for
bats on the site.
• Detailed recommendations are made for biodiversity enhancement through
compensatory habitat creation.
Hedge Assessment and Bat Activity Survey SWIFT ECOLOGY
C998 Brook Farm, Marden, Herefordshire 3
2 INTRODUCTION
2.1 Background
A length of roadside hedge at Brook Farm, Marden was assessed to determine its
ecological value and a bat activity survey was conducted around the farm buildings;
both were undertaken in connection with proposals to remove a section of the
hedge and to demolish some barns and portacabins prior to construction of a new
office building. Because the buildings to be demolished or removed have very low
potential to support roosting bats, no further assessment of roosting activity was
required. The hedge assessment and activity survey were carried out by Swift
Ecology on 11th July 2013. The site is located at approximate OS grid ref. SO521482.
2.2 Ecological Context
Brook Farm is situated in a rural setting just north of the village of Marden in central
Herefordshire (Plate 1). The site surveyed comprises a mix of large modern fruit
processing buildings with some older barns and temporary office accommodation
including several portacabins (Plate 2). The site is surrounded by farmed
countryside, which is dominated by grassland and some arable to the west, and by
soft fruit production under polythene to the east. The meandering, tree-lined River
Lugg lies 400 m to the west; immediately to the south is an area of accommodation
for seasonal workers on the fruit farm with some recreational facilities; there are
clumps and lines of trees close to an old farmhouse visible in Plate 2; areas of low
density housing in Marden lie 300 m to the south. There are some hedgerows and
scrub bordering the Brook Farm site, but there are no large woodlands within 2 km
of the site. These habitats provide some opportunities for foraging and/or roosting
bats.
Plate 1. Google Earth image showing the landscape context of Brook Farm, Marden.
The approximate area surveyed for bats is identified by a yellow outline.
Hedge Assessment and Bat Activity Survey SWIFT ECOLOGY
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3 METHODS
3.1 Hedge Assessment
The structure and species composition of the hedge and its associated ground flora
were assessed on the 11th July 2013. This assessment focused on the section
proposed for removal (shown in Plate 2). Notes of evidence of other wildlife species
were made. An evaluation of the effects of removal of the section of hedge was
made against key wildlife site criteria.
Plate 2. Google Earth image of the Brook Farm site, showing the locations of the
roadside hedge assessed (red line identified by red arrow) and the ten stations
occupied in sequence during the bat activity survey (yellow numbers); the two barns
assessed internally for signs of bat activity are identified by red triangles.
3.2 Bat Activity Survey
A single bat activity survey was carried out at dusk on 11th July 2013. A single
surveyor moved between ten pre-selected stations in sequence to record bat activity
for periods of five minutes at each station. The locations of these stations were
chosen to provide good coverage of the areas to be affected by the proposed
development; two of the stations were located beside the hedge proposed for
removal (see Plate 2). Each station was monitored at least twice during the survey
period of approximately two hours and twenty minutes. The surveyor also recorded
bat sounds while walking between stations.
During each circuit of the stations, the interiors of two barns proposed for
demolition were checked for signs of bat activity using bat detectors and a powerful
torch (these barns are identified in Plate 2). The western-most barn is open at its
eastern end and recording station 1 was located at this eastern end; the eastern
Hedge Assessment and Bat Activity Survey SWIFT ECOLOGY
C998 Brook Farm, Marden, Herefordshire 5
barn is normally kept closed and has been adapted for social events, so opportunities
for bat access and roosting are more limited.
Two ultrasonic bat detectors were used to detect and record bat calls; these
included an Anabat system. A digital recording device was connected to a manual
bat detector to store bat echolocation calls for subsequent analysis using Batsound
software. The bat activity survey approach was based upon the Good Practice
Guidelines for manual bat surveys (Hundt, 2012). Details of personnel, equipment,
timings and weather conditions are given in Table 1.
Table 1: Brook Farm, Marden Bat Activity Survey Details
Survey type Dusk
Date 11 July 2013
Weather conditions Dry, calm and clear sky after a warm day. Start temp. 20 oC; finish 13 oC
Sunset
/sunrise time (BST)
2129
Start time 2114
End time 2335
Personnel Johnny Birks
Equipment 1 x Pettersson D240x, 1 x Anabat
3.3 Constraints
July is a reasonable month for assessing the botanical interest of hedges because
many characteristic species are identifiable then. The bat activity survey was carried
out in reasonable weather conditions.
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C998 Brook Farm, Marden, Herefordshire 6
4 RESULTS
4.1 Hedge Assessment
The section of hedge that will be affected by the proposed development comprises
an approximately 30 m length that runs north to south between the Brook Farm site
and the minor road that leads north from the village of Marden towards Bodenham.
The hedge has been managed by standard trimming methods; at its maximum it is
approximately 3 m high and 1-2 m wide at the base. A small drainage ditch runs
along the roadside of the hedge for the majority of its length; at its southern end this
ditch is piped and runs underground.
Along the majority of its length the hedge is composed of a limited range of native
broadleaved shrub species dominated by elm Ulmus sp. (probably English elm Ulmus
procera) and hawthorn Crataegus monogyna, with field maple Acer campestre
occasionally present. At its southern end the hedge is less natural in character, with
Leylandii the dominant woody species and a single pedunculate oak Quercus robur
present; this less natural part of the hedge extends for about 10 m and is bordered
by a 1.5 m high dilapidated larch-lap fence on the roadside.
The more natural sections of the hedge are characterised by a range of climbing
plants including cleavers Galium aparine, hop Humulus lupulus, ivy Hedera helix,
bramble Rubus fruticosus and bittersweet Solanum dulcamara; in the less natural
section of the hedge, of these climbers, only ivy is sparsely present.
The ground flora beneath the hedge comprises a limited range of common wayside
flowers such as hedge woundwort Stachys sylvatica, white dead-nettle Lamium
album and black medick Medicago lupulina; coarse grasses such as cock’s foot
Dactylis glomerata; and ruderal plants such as nettle Urtica dioica, dock Rumex sp.,
spear thistle Cirsium vulgare and creeping thistle Cirsium arvense.
4.2 Bat Activity Survey
One bat activity survey was conducted at the site, as described in section 3.2.
The raw data from this survey are presented in Table 2, and the main findings are
summarised below.
Although bat activity was recorded at nine of the ten stations during the survey, the
level of bat activity was generally very low and only three bat species were recorded:
common pipistrelles Pipistrellus pipistrellus were recorded most frequently and most
widely (at eight of the ten recording stations); soprano pipistrelles Pipistrellus
pygmaeus were recorded twice at station 2 only; and noctules Nyctalus noctula were
recorded twice, once each at stations 4 and 5.
Most bat activity and the greatest bat species diversity (albeit very limited) were
recorded at stations on or close to the line of trees on the southern edge of the site.
Hedge Assessment and Bat Activity Survey SWIFT ECOLOGY
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Very little bat activity was recorded at stations 8 and 9 beside the roadside hedge
proposed for removal.
No bats were observed or recorded inside either of the two barns subject to internal
checks (each barn was checked on three separate occasions, as indicated in Table 2
below).
Table 2: Bat activity survey results from the Brook Farm site on 11th July 2013.
Station
no.
Timing
of visits
(BST)
Activity/comments
1 (east
end of
barn)
2114-19 No bat activity
2213-18 No bat activity
2314-19 2318 - Faint pass by common pipistrelle over barn
Note barn interior was checked for bats during each of the periods above
2 2120-25 No bat activity
2219-24 No bat activity
2320-25 2320-23 - Several foraging passes by common pipistrelles near trees to south of
station 2
3 2125-30 No bat activity
2224-29 2225 – Foraging pass by common pipistrelle along line of conifers
2325-30 2325 and 2329 – Passes by soprano pipistrelle
2326-2330 – Several passes by common pipistrelles along tree line.
Internal checks of eastern barn at 2130 (no bats), 2230 (no bats) and 2331 (no bats)
4 2130-35 No bat activity
2231-36 2231 – Pass by noctule overhead
5 2135-40 No bat activity
2236-41 2236 – Pass by noctule
2240 – Brief, faint pass by common pipistrelle
6 2143-48 No bat activity
2244-49 2244 – Common pipistrelle feeding around security light?
7 2148-53 No bat activity
2249-54 2249 – Common pipistrelle pass
8 2153-58
2254-59 2255 and 2257 – Passes by common pipistrelle along hedge line
9 2158-
2203
No bat activity
2259-
2304
No bat activity
10 2203-08 No bat activity
2304-09 2305 and 2308 – Passes by common pipistrelle
Hedge Assessment and Bat Activity Survey SWIFT ECOLOGY
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5 EVALUATION
5.1 Evaluation of Hedge against Wildlife Site Criteria
The section of hedge proposed for removal is assessed as follows against standard
Wildlife Site Criteria:
• Diversity
The hedge section is not very diverse; relatively few species are present.
• Rarity
No rare species were in evidence, and habitats present are common in a county
context. However, the presence of English elm is of some value as a species that
has declined in past decades.
• Size
The area of the hedge section is small (< 100 m2) although it is contiguous with a
longer stretch of hedge and other tree and shrub cover.
• Naturalness
The hedge section is a man-made feature, albeit mainly composed of native
species, which has been subject to frequent management to maintain its current
form. Therefore, its naturalness is relatively low.
• Fragility
The hedge section has been managed frequently, is located adjacent to a road,
and therefore is not particularly fragile.
• Typicalness
Because of the effects of management, the hedge section is unlikely to represent
a very typical example of any particular habitat other than roadside hedges.
• Ecological position
The hedge section is an integral part of a longer stretch of hedge in an area
where the abundance of tree and shrub cover and wildlife corridors is relatively
limited because of the open character of the agricultural landscape. The hedge
may be used as a dispersal route by certain scarce species such as dormouse
Muscardinus avellanarius. Therefore, the hedge section’s position as a linking
part of a corridor is of some importance.
• Significant populations of species
The hedge section is unlikely to support significant populations of any wildlife
species. However, it is likely to support small populations of certain species,
including nesting birds.
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• Potential value
The value of the hedge section could be enhanced by appropriate management,
such as a reduced frequency of cutting.
• Physical and visual access
A road runs adjacent to the hedge section. There is no public access on its
eastern side.
• Educational value
The hedge section is unlikely to have significant value as an educational resource.
• Community and amenity value
Not known but probably limited.
• Aesthetic appeal and landscape character
The hedge section has limited aesthetic appeal or landscape character.
• Geographical position
The hedge section lies to the north of the village of Marden.
• Recorded history
This is not known, though the low shrub diversity suggests that the hedge is not
of a great age.
• Continuity of land use
The hedge section has had some continuity of land use due to its persistence as a
roadside feature.
In summary, the habitats and plant species found on the hedge section are generally
widespread and common. In view of this assessment and the relatively short length
of hedge proposed for removal, the loss of this section will have a minor, short-term
adverse effect upon biodiversity in the locality. In the longer term, there will be
significant net biodiversity gains as a consequence of compensatory habitat creation
on the site as part of this development.
5.2 Bats
Levels of bat activity on the site were low during the dusk survey, and there was no
evidence of bats making use of the two barns that were checked internally. This low
level of bat activity and the low bat species diversity at the site is consistent with the
relatively poor bat foraging habitat present (little or no vegetation is present within
the site to support insect prey) and the low bat roosting potential of the buildings
(relatively modern structures built of materials other than timber and stone that are
not normally favoured by roosting bats) on the site.
The low level of bat activity along the roadside hedge proposed for removal suggests
that it is neither a significant foraging habitat nor commuting route for bats.
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The majority of bat activity and the greatest species diversity (albeit both rather
limited) was associated with the southern edge of the site, where a line of trees
provides both foraging habitat and a commuting route. This line of trees will be
removed as part of the proposed development, so there will be some impact upon
bats as a consequence.
Overall, the proposed changes to the site (removal of the roadside hedge on the
western boundary and trees along the southern boundary, and demolition or
removal of buildings and construction of a new office building) will have a minor
adverse impact upon bat activity in the locality. However, this will be a relatively
short-term effect because compensatory habitat creation will lead to a significant
increase in the availability of foraging and commuting habitat for bats on the site.
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6 RECOMMENDATIONS
6.1 Precautionary Approaches to Demolition/Removal Works
6.1.1 Bats
Given the lack of evidence of any use of the buildings by bats, and their very low
suitability for roosting bats, it is unlikely that there will be any impact on bats or bat
roosts as a result of the demolition of the barns and the removal of the portacabins
on the site. Nevertheless it is not possible to rule out occasional bat use of such
structures. Therefore the following precautionary approach is recommended:
• All roofing materials should be removed carefully by hand and inspected
for the presence of roosting bats
• All site workers will be made aware of the slight possibility of finding bats
and the procedure to follow should they be found. In the unlikely event
that a bat is discovered, contractors will stop work immediately and
telephone an ecological professional qualified to deal with bats.
Telephone numbers of such will be held on site (Swift Ecology numbers:
07825 711862 or 01926 642541). Further surveys and a European
Protected Species Licence may be required before works can continue.
• Should any bats fall out of structures or be injured, they will be gently
placed in a secure ventilated box (e.g. a cardboard box) by the contractor
and left in a cool dark place, until appropriate advice can be sought. Bats
should not be handled without gloves.
• A copy of these recommendations will be available to site workers and
displayed on site.
6.1.2 Nesting Birds
The roadside hedge and the buildings may be used by nesting birds. All nesting birds
are protected by law. To avoid committing an offence, any works should be
undertaken outside the bird breeding season (March to August inclusive). If this is
not possible, the hedge and buildings should be checked immediately prior to works
commencing by a suitably qualified ecologist. If there are breeding birds present,
works cannot continue until the chicks have fledged and left the nest.
6.2 Habitat Compensation and Biodiversity Enhancement Measures
In order to compensate for the loss of a section of roadside hedge, and to enhance a
site that currently is of relatively low biodiversity value, the following new areas of
wildlife habitat will be created as part of the development (identified on the
architect’s plan in Appendix 1); these will be in addition to new ornamental plantings
close to the buildings that are not considered here:
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Native species hedge
A new hedgerow will be established to link the north-west corner of the existing
main building with the roadside to the west. Running roughly east to west and
extending to a length of approximately 15 m, this hedge will comprise locally native
shrub species, including the following:
Field maple Acer campestre Hawthorn Crataegus monogyna Hazel Corylus avellana Dogwood Cornus sanguinea Blackthorn Prunus spinosa Guelder rose Viburnum opulus
Holly Ilex aquifolium
Yew Taxus bacatta
This hedge will be encouraged to grow to a minimum height of 3 m and a minimum
width at its base of 1.5 m. It will be managed so as to retain a dense structure with
active fruiting. It will not be trimmed on both sides every year, so that some fruit
production will be available for consumption by wildlife during the autumn and
winter months.
Strategic block of native trees and shrubs
To the north of the existing main building, linking with the northern end of the
roadside hedge at the north-western corner of the site and extending along the
northern site boundary toward the east, a new, permanent block of native trees and
shrubs will be established. This will comprise a mix of species including standard
trees such as pedunculate oak Quercus robur, wild cherry Prunus avium and silver
birch Betula pendula, as well as the shrubs listed above in connection with the new
hedge. This new block of semi-natural habitat will be managed so as to establish and
maintain a diversity of tree and shrub species, with a two-tier structure comprising a
low density of standard trees over a denser shrub layer with linear gaps.
The planting will be designed strategically to create effective links with existing
hedges and areas of trees and shrubs; this will enhance landscape connectivity for
bats and other wildlife in line with the principles enshrined in Landscape and urban
design for bats and biodiversity (Gunnell et al., 2012). In order to provide a viable
commuting route and foraging area for bats, artificial lighting on the site must be
effectively controlled so that this new habitat feature remains dark at night.
Hedge Assessment and Bat Activity Survey SWIFT ECOLOGY
C998 Brook Farm, Marden, Herefordshire 13
7 RELEVANT LITERATURE
Gunnell, K., Grant, G. and Williams, C. (2012). Landscape and urban design for bats
and biodiversity. Bat Conservation Trust, London.
Hundt, L. (2012). Bat Surveys – Good Practice Guidelines, 2nd edition. Bat
Conservation Trust, London.
Mitchell-Jones, A.J. (2004). Bat Mitigation Guidelines. English Nature, Peterborough,
England.
Schofield, H.W. & Mitchell-Jones, A.J. (2004). The bats of Britain and Ireland. The
Vincent Wildlife Trust, Ledbury, England.
APPENDIX 1 Habitat compensation and enhancement measures