vsm estates limited project model, raf uxbridge bat survey

Doc Ref: PDF/MRU/048October 2010

VSM Estates Limited

Project MoDEL, RAF Uxbridge Bat Survey

Halcrow Group Limited Griffin House 135 High Street Crawley West Sussex RH10 1DQ

Tel +44 (0)1293 434500 Fax +44 (0)1293 434599

www.halcrow.com

Halcrow Group Limited has prepared this report in accordance with

the instructions of their client, VSM Properties Limited, for their sole

and specific use. Any other persons who use any information

contained herein do so at their own risk.

© Halcrow Group Limited 2010

VSM Estates Limited

Project MoDEL, RAF Uxbridge

Bat Survey

October 2010

Halcrow Group Limited

Halcrow Group Limited Griffin House 135 High Street Crawley West Sussex RH10 1DQ

Tel +44 (0)1293 434500 Fax +44 (0)1293 434599

www.halcrow.com

VSM Estates Limited

Project MoDEL, RAF Uxbridge

Bat Roost Survey

Contents Amendment Record This report has been issued and amended as follows:

Issue Revision Description Date Signed

1 0 1st Draft Report 22.09.10 CKD

1 1 Review 01.10.10 DGW

1 2 Final Draft 04.10.10 DGW

1 3 Amendments 15.10.10 CKD

2 4 Client comments incorporated 21.10.10 CKD

Contents

1 Introduction 1 1.1 Background 1 1.2 Survey Objectives 2

2 Legislation 3

3 Methodology 4 3.1 Desk Study 4 3.2 Building Roost Survey 4

3.3 Bat Emergence Survey 4 3.4 Evaluation Methodology 5

3.5 Limitations of the Survey 5

4 Results 6 4.1 Desk Study 6 4.2 Bat Roost Survey Results 6 4.3 Bat Emergence Survey Results 7

5 Evaluation & Potential Impacts 8 5.1 Evaluation 8 5.2 Potential Impacts 9

6 Recommendations and Conclusions 10 6.1 Recommendations 10 6.2 Conclusions 11

7 References 12

Appendix A – Bat Survey Raw Data 13

Appendix A – Bat Survey Raw Data 13

Appendix B - Figures 16

Date: October 2010 1 RAF Uxbridge Bat Survey Report

1 Introduction

1.1 Background

Halcrow Group Limited was commissioned by VSM Estates Ltd, to carry out an updated bat

survey of buildings at RAF Uxbridge, hereafter referred to as the ‘site’. The site is currently

in use as a Royal Air Force military base and is situated in Uxbridge, on the western fringe of

Greater London, in the London Borough of Hillingdon, centred on Ordnance Survey Grid

Reference TQ 063 835.

The site is bordered by a residential development to the north and east, Hillingdon Road

(A4020) to the west and by the River Pinn and Hillingdon golf course to the south.

Redevelopment of the site is proposed for mixed residential, leisure, retail and office

development, with works scheduled to commence in April 2011.

The site consists predominantly of buildings and amenity grassland with a high number of

trees, woodland, some semi-improved grassland and the River Pinn, which runs north to

south through the site (Halcrow, 2009b).

Bat activity surveys were previously carried out at the site and results are presented within an

earlier report (Halcrow, 2009a). Following recommendations made by Natural England

further surveys were undertaken at the site which focused upon buildings where internal

access had previously been restricted. In addition, buildings previously identified as in use by

roosting bats were subject to updated bat emergence surveys to ensure the data collected is

sufficient to support an application for a European Protected Species Licence. The updated

surveys were undertaken by a Halcrow licensed bat specialist (licence number: 20101705) and

experienced assistants on the 8th, 13th and 14th August 2010 and the results are presented

within this report. This report will provide recommendations to minimise impacts upon

roosting bats and will help to inform a local planning authority decision to ensure the

proposed development is undertaken in full compliance with all EU/UK legislation afforded

to bats.


1.2 Survey Objectives

The objectives of the survey were to determine:

• whether any buildings within the site, where internal access had

previously been restricted and that are scheduled for demolition, contain

any potential bat roosts and/or evidence of bats;

• to update bat emergence survey results to the known bat roost locations;

• to inform the need for further surveys, as appropriate;

• the legal implications of development proposals; and

• to inform on the requirement for a European Protected Species licence,

for any works carried out that might affect a bat roost.


2 Legislation

All bat species and their roosts are protected in the UK under the Conservation of Habitats

and Species 2010, which implement the EC Habitats Directive 92/43/EEC.

All bat species and their roosts are also protected under the Wildlife and Countryside Act

1981 (as amended), through inclusion in Schedule 5.

Taken together, these acts and regulations make it illegal to:

• intentionally or deliberately kill, injure or capture bats;

• deliberately or recklessly disturb bats;

• damage, destroy or obstruct access to bat roosts; possess or transport a

bat or any part of a bat, unless acquired legally; and

• sell, barter or exchange bats, or parts of bats.

Developments that compromise the protection afforded to bats under the provisions of the

Conservation of Habitats and Species 2010 will almost invariably require a European

Protected Species (EPS) licence to do so lawfully, from the Wildlife Management Licensing

Service (Natural England). Three tests must be satisfied before Natural England can issue a

licence to permit otherwise prohibited acts:

1. Regulation 53(2)(e) states that licences may be granted to “preserve public health or

public safety or other imperative reasons of overriding public interest including those of a social

or economic nature and beneficial consequences of primary importance for the environment.”

2. Regulation 53(9)(a) states that a licence may not be granted unless “there is no

satisfactory alternative”.

3. Regulation 53(9)(b) states that a licence cannot be issued unless the action

proposed “will not be detrimental to the maintenance of the population of the species

concerned at a favourable conservation status in their natural range”.


3 Methodology

3.1 Desk Study

A desk study was conducted as part of an Ecological Appraisal (Halcrow, 2009b). Records

were provided by Greenspace Information for Greater London (GiGL), (which includes all

records from the London Bat Group); of bats recorded within a 2km radius of land

encompassing the site. This area was considered to be sufficient to cover the likely zone of

influence of the proposed re-development.

3.2 Building Roost Survey

An internal and external inspection of built structures, where internal access had previously

been restricted during the 2009 bat survey (refer Table 1) and which are scheduled for

demolition, was undertaken by two licensed bat specialists on the 8th August 2010. Access

into all roof voids (if present) of the built structures was gained and an inspection for

evidence of roosting bats was undertaken using high light intensity torches. Evidence

indicating potential usage of a built structure by roosting bats includes:

• presence of live/dead bats;

• droppings, urine staining;

• scratch/rub marks around potential access points.

NB: External inspections of these buildings for suitable bat access points and bat emergence

surveys were undertaken upon these structures during the 2009 bat survey

The method undertaken during the building roost survey conformed to standardized

methodologies as defined in the Bat Workers Manual (Mitchell-Jones & McLeish, 2004) and

the Bat Surveys – Good Practice Guidelines (Bat Conservation Trust, 2007).

3.3 Bat Emergence Survey

Dusk bat emergence surveys were undertaken on built structures that were previously

identified as bat roosts (refer Table 2) and focused upon cracks or crevices that were

previously identified (Halcrow, 2009a) as ingress and egress points for bats. The surveys

commenced 0.5 hour prior to sunset until 2.5 hours after dark to ensure all species, if

present, would be encountered. The surveys were undertaken by surveyors, equipped with

hetrodroyne ‘Bat Box Duet’ bat detectors and auto remote sensing recordable bat detectors

‘Anabat’, which enables bat calls to be analysed via computer software at a later date. To

enable a clear view of all aspects of the built structures, the operatives were situated upon

diagonal ends of the building from each other.


The survey methods conformed to standardized methodologies as defined in the Bat Workers

Manual (Mitchell-Jones & McLeish, 2004) and the Bat Surveys – Good Practice Guidelines (Bat

Conservation Trust, 2007).

3.4 Evaluation Methodology

The evaluation is based on guidance from the Institute of Ecology and Environmental

Management (IEEM, 2006). The level of value of the bat population is assigned using a

geographic frame of reference, i.e. international being most important, then national,

regional, county, city, local and lastly, within the immediate zone of influence of the

proposals only.

The evaluation is made using a variety of characteristics, including the rarity of populations,

either locally or within a wider area, the vulnerability of species (for example, due to

disturbance or fragmentation from other populations), and statutory recognition of

biodiversity importance through inclusion in local or national biodiversity action plans. Note

that legal protection is not, in itself, a consideration in the evaluation of species.

3.5 Limitations of the Survey

Access into all built structures where access had been previously restricted was gained and

the bat emergence surveys were undertaken during the optimal bat activity season. Therefore

there were no limitations associated with the survey and the results presented within this

report are considered to provide an accurate account of bat activity at the site at the time of

the survey.


4 Results

4.1 Desk Study

The following records have been received from GiGL (dated 9th April 2009); provided by the

London Bat Group and include the following:

• Common Pipistrelle Pipistrellus pipistrellus roost is located approximately 1.7km west

of the site and a second Common Pipstrelle roost is located approximately 1.5km

south-west of the site;

• Soprano Pipstrelle Pipistrellus pygmaeus roost is located 1.8km north of the site;

• Three separate Noctule Nyctalus noctula roosts are situated 0.7km (east), 0.8km (east)

and 1.0km (north-east) of the site; and

• Two Daubenton’s bat Myotis daubentoni roosts are located approximately 1km south-

west and 1km east of the site.

4.2 Bat Roost Survey Results

No evidence of bats was found in any of the buildings during the internal inspections, where

access was previously restricted, and consequently any of these buildings surveyed are not

considered to be in use by roosting bats.

Table 1: Internal Building Inspection Results

Building

Number

Description Potential for

Roosting Bats

Evidence

of Bats

Garages: 113,

116, 117, 126,

128a, 128b, 128c,

143, 163, 177

Single storey brick garages with pitched tiled

roof and lowered ceiling. No suitable ingress

and egress opportunities for bats.

Low None

139 Officers

Mess

Large single storey structure circa early 1900s

with pitched tiled (lined) roof and internal roof

voids. Numerous gaps between the tiles

provide suitable ingress and egress

opportunities for bats

High None

103 Welfare

Centre

A row of four two storey houses, constructed

of painted brick. Pitched tiled roofs and

internal roof voids are present. Numerous

missing tiles and gaps between the roofing tiles

High None


Building

Number

Description Potential for

Roosting Bats

Evidence

of Bats

provide suitable ingress and egress

opportunities for bats.

6 Boxer Tower Metal tower (resembles a typical phone mast.) Negligible None

86 Gas Meter

Housing

Single storey brick structure with pitched tiled

roof. Numerous gaps are present between the

roofing tiles.

Moderate - Low None

4.3 Bat Emergence Survey Results

A total of 17 bats were observed emerging from gaps between the wooden window frames

and hanging tiles situated upon the north and southern elevation of building number 138

(Officers Quarters). The majority of the bats flew in an easterly direction before circling back

towards the river Pinn.

Two Brown Long-Eared Plecotus auritus bats were observed flying near to a gap in the ridge

tiles situated upon the eastern elevation of building 146D (Somme accommodation block).

However due to decreasing light intensities positive emergence could not fully be ascertained

at the time of the survey.

No bats were observed emerging from building numbers 226 (Indoor Firing Range) and 212

(Music Services Building) during the 2010 updated bat emergence survey.

Table 2: Bat Emergence Survey Results

Date of

Survey

Temperature Cloud

Cover

Building

No.

Bat Access No of Bats

Emerged

Species

08.08.10 180C 40% 138 Gaps under wooden

window frame and

hanging tiles: North

Elevation.

Southern Elevation

15

2

SP

SP

13.08.10 140C 100% 146D Gaps under ridge tiles,

east elevation

2 (likely) BLE

14.08.10 140C 100% 212 Vent on east elevation None n/a

14.08.10 140C 100% 226 Vent on east

elevation/Gaps under

wooden cladding

None n/a

SP = Soprano Pipistrelle bat. BLE = Brown Long Eared bat.


5 Evaluation & Potential Impacts

5.1 Evaluation

A total of 17 Soprano Pipistrelle Pipistrellus pygmaeus bats were observed emerging from gaps

beneath the hanging tiles and around the wooden window frames upon the north and

southern elevation of building 138. No Common Pipistrelle Pipistrellus pipistrellus bats were

encountered emerging from this structure during this (2010) survey. The numbers

encountered overall during the 2010 survey were found to have increased from 7 (5 x

Soprano Pipistrelle and 2 x Common Pipistrelle bats) individuals since the 2009 July

emergence count (Halcrow, 2009a). Given the low numbers of bats encountered, over two

consecutive years the roost is not considered to be used as a maternity roost but is likely to

be a summer roost for up to a maximum of 20 individuals. Therefore building 138 has been

assessed in terms of its importance to Pipistrelle bats and is considered to be of at least a

local level of importance.

Evidence of Long-Eared bats was found within the southern gable end roof void of building

146D (Somme Accommodation Block) during the 2009 bat surveys (Halcrow, 2009a). Two

Brown Long-Eared bats were observed at 19.43 hours (close to the expected emergence time

for this species at this time of the year), close to a gap in the ridge tiles, upon the eastern

elevation, which is situated very close to the southern gable end (known roost location).

Positive emergence could not be determined at the time of the survey as light intensities had

diminished; however, given the evidence present within the building, it is considered highly

likely that these two bats did emerge from this structure. Given the low numbers of Brown

Long-Eared bat activity around building 146D and the low levels of droppings present

within the roof void, it is not considered to be in use by Brown Long-Eared bats as a

maternity roost. However, the roost is likely to be used year round for up to 5 individuals

(including summer and hibernation season), as Long-Eared species often remain at a single

roost location throughout the year. Records provided by GiGL indicate that there are no

known roosts for long eared bat species located within a 2km radius of the site. Brown

Long-Eared bats were however previously recorded and observed emerging from a private

residential dwelling (located outside the site boundary) in the far north-eastern corner of the

site and were also recorded foraging within close proximity to the River Pinn (Halcrow,

2009a). Therefore, building 146D has been assessed in terms of its importance to Brown

Long-Eared bats and is considered to be of at least a local level of importance.

No bats were observed emerging from building numbers 226 and 212, however relatively

low numbers; 7 Soprano Pipistrelles were observed emerging from building 226 (Indoor

Firing Range) and 1 Soprano Pipistrelle bat emerged from building 212 (Music Services

Building), during the 2009 bat survey (Halcrow, 2009a). Therefore, it is likely that these


buildings are used occasionally as a summer roosts for up to a maximum of 10 Soprano

Pipistrelle bats. Buildings 226 and 212 have been assessed in terms of their importance to

Soprano Pipistrelle bats and are considered to be of importance within the zone of

influence only.

Building number 40 (Hillingdon House) and a telegraph pole (situated immediately adjacent

to Hillingdon House) were also identified as roosts for limited numbers of Soprano

Pipistrelle bats and one Noctule Nyctalus noctula roost (oak tree) was also confirmed to be

present within the site boundaries, during the 2009 bat survey (Halcrow, 2009a). However

these structures/features are scheduled to be retained, therefore no updated bat surveys

during 2010 were considered necessary. Similarly, previous bat emergence/activity surveys

were conducted across the entire site and focused upon many buildings including the

buildings with limited access and no evidence of bats was found and, therefore, no further

bat emergence surveys upon these structures were considered necessary.

5.2 Potential Impacts

A total of seven bat roosts are known to be present (Halcrow, 2009a) within the site

boundaries, supporting four different species of bats (Halcrow, 2009b). However only

building numbers 138, 212, 226 and 146D, which support bat roosts are scheduled to be

demolished as a result of the proposed works. A total of six species of bat have been

recorded foraging within the site (Halcrow, 2009a) and in the absence of suitable mitigation,

potential adverse impacts that may arise from both the construction and operation of

development at the site could include:

• Death or injury of bats during the construction phase;

• Loss of potential roosts within the buildings;

• Loss of foraging and commuting habitat;

• Disturbance caused by increased noise and lighting within the zone of

influence during the construction phase;

• Severance of commuting routes, through the creation of gaps in, or

removal of, linear features;

• Isolation of on-site or off-site bat roosts through the loss of important

commuting corridors.


6 Recommendations and Conclusions

6.1 Recommendations

A number of bat roosts are present within the RAF Uxbridge site and the following

recommendations are provided to ensure that re-development of the site undertaken is

legally compliant with all EU/UK legislation afforded to bats.

1. In the absence of suitable mitigation measures being implemented at the site,

the development will result in a loss of roosts for Brown Long-Eared,

Common Pipistrelle and Soprano Pipistrelle bats. Where it is necessary to

destroy a roost to facilitate the development, an application for a European

Protected Species Licence (EPSL) will be necessary to ensure the

development and destruction of a bat roost is carried out in full compliance

with all EU/UK legislation afforded to bats.

2. EPSL applications are made to the Wildlife and Licensing Unit detailing an

appropriate level of mitigation suitable for the bat species likely to be affected

by the works. A licence application once prepared can take up to 30 working

days and/or up to three months before a licence permitting demolition is

granted, therefore the works programme should take this time restriction into

consideration. Seasonal restrictions relating to the demolition of buildings

used as roosts by bats will also be implemented as part of the mitigation

process.

3. Suitable bat mitigation measures can include retention of roosts or the

provision of new roosting opportunities. Bat mitigation measures for the site

should be explored and incorporated into a bat mitigation strategy report.

Generic bat mitigation measures are provided below for guidance and include:

• Demolition of roost identified as being in use during the summer months

to be demolished/soft stripped between October – March, inclusive.

Specific ‘soft stripping’ (removal of all roofing features, soffits, hanging

tiles and bargeboards is to be undertaken by contractors using hand tools

only, on all structure known to support bat roosts and can only be

undertaken under the supervision/guidance of a licensed bat specialist)

mitigation measures will be set out with the bat mitigation strategy

report/EPSL method statement. (NB: These seasonal time


restrictions are critical and will be necessary to ensure an EPSL is

granted to permit demolition).

• As building 146D Somme Barrack Block is in use possibly year round by

Long-Eared bats, demolition of this structure should avoid the

hibernation period 15th November – 15th March. As this structure is also

in use during the summer period, demolition should therefore only be

undertaken between 15th March – 15th April 2010 and/or the September

15th – November 15th. All features associated with the internal and

external features of the roof should be removed by contractors by hand

(soft stripped) and under the supervision of a licensed bat specialist. (NB:

These seasonal time restrictions are critical and will be necessary to

ensure an EPSL is granted to permit demolition).

• Prior to demolition/destruction of a bat roost, replacement roosts “like

for like” must be provided within the site boundaries. These replacement

roosts should be designed and incorporated into the bat mitigation

strategy report.

• The use of artificial lighting should be avoided 1 hour prior to dusk until

1 hour after dawn between 1st May – 1st September inclusively. The

implementation of new permanent lighting at the site should aim to

minimise the impact on bats and their prey. The use of high pressure

sodium lamps with a flat glass cover (which filters ultraviolet light and

reduces light spread) and should also feature shields, louvers or shrouds

fitted to minimise light spill is recommended.

6.2 Conclusions

VSM Estates propose to redevelop a site currently in use as RAF Uxbridge. Bat surveys have

been carried out at the site and at least six species of bat are considered to be utilising the site

for roosting, foraging and commuting purposes (Halcrow, 2009b). It is considered likely that

the bats using the site will be impacted on by the proposed works in the absence of suitable

mitigation. Recommendations presented within this report aim to minimise the impacts of

the proposed works upon bats within the site and the local area and provide guidance in

relation to the additional survey effort and potential mitigation required to adequately inform

a successful EPSL application if demolition of built structures/assets and trees supporting

bat roosts cannot be avoided.


7 References

Bat Conservation Trust (2007) Bat Surveys – Good Practice Guidelines, Bat Conservation Trust,

London

Halcrow Group Limited (2009a) RAF Uxbridge: Bat Roost Survey Crawley, UK

Halcrow Group Limited (2009b) RAF Uxbridge: Ecological Appraisal, Crawley, UK.

Institute of Ecology and Environmental Management (2006) Guidelines for Ecological Impact

Assessment within the United Kingdom. IEEM. Winchester.

Mitchell-Jones, A.J. & McLeish, A.P. (2004) Bat Workers Manual 3rd Ed, Joint Nature

Conservation Committee, Peterborough.

Mitchell-Jones, A.J. (2004). Bat mitigation guidelines. English Nature, Peterborough.


Appendix A – Bat Survey Raw Data

Date 08.08.10

Site Uxbridge

Location Building 138: North/East Elevation Corner

Weather 180C/ 40 % Cloud Cover/Light Breeze

Sunset Time 19.28

Time Species Activity

19.00 Start survey

19.50 SP Emerged from a gap beneath the lead flashing, located to the right of the 2nd

window on north elevation. Flew west.

19.52 SP Emerged from a gap in 2nd window frame, north elevation, flew west and 1 bat

returned to the roost.

19.55 SP x 2 Emerged from same gap in window frame

19.55 SP As above

19.55 SP Emerged from beneath a hanging tile, 1st window, right of plant room,

northern elevation.

19.57 SP Emerged from a gap in window frame (2nd window on left), northern elevation,

foraged around trees and flew west.

19.58 SP x 3 Emerged as above

19.59 SP x 2 Emerged as above

20.00 SP Emerged from gap in the window frame, 3rd window from left, north elevation.

20.07 SP Emerged from a gap in window frame, 2nd from the left, north elevation.

20.28 SP Flyby – heading towards the river.

22.00 Survey Stopped

Location: Building 138: South/West Elevation Corner

19.55 SP Heard not seen


19.59 SP Flew over building from north west (from direction of surveyor 1)

20.00 SP Flew from north

20.01 SP Emerged from hanging tiles, east elevation, flew east


20.08 SP Emerged from eastern elevation, hanging tiles, near the top of the roof.


Date 13.08.10

Site Uxbridge

Location Building 146D (Somme Accommodation Block): South/East Elevation

Corner

Weather 150C/ 100 % Cloud Cover

Sunset Time 19.28


19.00 Start survey

19.31 CP Heard not seen

19.43 SP Flew over roof, eastern elevation

20.00 BLE Heard briefly not seen

20.04 BLE Very close to gap near ridge tiles, east elevation. Possible emergence,

only silhouette visible too dark. Bat flew east towards River Pinn.

20.04 BLE 2nd bat, as above

20.27 – 20.00 SP Occasional foraging around mature Horse Chestnut tree

Location: North-West Corner: Building 146D

19.18 CP? Flying from north over the top of the building

19.20 CP Seen flying from north of site towards building

19.42 CP Flew over roof, from north

20.01 CP Brief flyby


Date 14.08.10

Site Uxbridge

Location Building 226 (Indoor Firing Range): East Elevation Vent

Weather 120C/ 100 % Cloud Cover

Sunset Time 19.28


19.00 Start survey

19.37 SP Foraging near mature avenue of Horse chestnut trees, flew from

direction of river


19.52 SP Constant foraging around trees, 1 x bat

20.06 SP Foraging activity stopped near trees

20.18 SP Flyby


21.07 SP Foraging near mature tree

21.07 – 21.35 SP As above

Location: Building 165: East Elevation Vent

19.45 Pip Flew past NW - SE

20.11 SP Flew past S - N

Key: SP = Soprano Pipistrelle. CP = Common Pipistrelle. BLE = Brown Long-Eared. Pip = Pipistrelle

species.


Appendix B - Figures

Figure 1: Bat Survey Plan

vsm estates limited project model, raf uxbridge bat survey

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