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WORCESTER BAT GROUP PROJECT Author: Graham Davison MONITORING AND PROTECTION OF LESSER HORSESHOE BATS (RHINOLOPHUS HIPPOSIDEROS): UNDERCROFT, WORCESTER CATHEDRAL Date: November 2013
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Page 1: WORCESTER BAT GROUP PROJECT - Microsoftbtckstorage.blob.core.windows.net/site104/Bat... · 1.1 Use by bats Worcestershire bat group have been monitoring bat activity in the cathedral

WORCESTER BAT GROUP PROJECT

Author: Graham Davison

MONITORING AND PROTECTION OF

LESSER HORSESHOE BATS

(RHINOLOPHUS HIPPOSIDEROS):

UNDERCROFT, WORCESTER CATHEDRAL

Date: November 2013

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1 Worcestershire Bat Group Monitoring and Protection of Lesser Horseshoe Bats Worcester Cathedral Undercroft, Worcester

1 BACKGROUND TO PROJECT

1.1 Use by bats

Worcestershire bat group have been monitoring bat activity in the cathedral

undercroft since September 2010 and have confirmed that the undercroft is used as

a roost site between the months of September and March. During this period it

provides the stable internal conditions required by hibernating lesser horseshoe bats

(maximum count 11 individuals) as well as small numbers of Myotis bats (maximum

count 1 individual Daubenton’s bat Myotis daubentonii on several occasions). The

maximum number of lesser horseshoe bats recorded exiting the roost at dusk is 17

(recorded 28 September 2010).

1.2 Use by people

The cathedral undercroft has a long history of unauthorised persons using the ruins

as a rough sleeping area. Correspondence with the Cathedral Service Department

Manager indicates that people have been breaking into the undercroft for at least 20

years, but that the problems have been getting worse. Historically there were no

serious concerns in the winter months, but this is no longer the case.

Since monitoring has been carried out by Worcester Bat Group, sleeping bags and

associated personal items have been present in the undercroft throughout together

with candles, drinks cans/bottles, small fires and evidence of less savoury activities

(used syringes, prophylactics etc). The proximity of human activity with lesser

horseshoe bats in hibernation causes significant concerns about deliberate or

accidental killing or injury of hibernating bats, along with potential for frequent

disturbance during the coming and going of rough sleepers and potential for further

fires and other damaging activities within the undercroft. Significant damage was

caused to the railings which protect the undercroft in March 2011.

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2 Worcestershire Bat Group Monitoring and Protection of Lesser Horseshoe Bats Worcester Cathedral Undercroft, Worcester

2 PROJECT PURPOSE

2.1 Objectives of the proposed project.

The project proposals were for the installation of a fixed, permanent metal grille

under a series of stone arches, which currently serve as the point of unauthorised

human access into the Cathedral undercroft of Worcester Cathedral together with

installation of 4 Schwegler bat boxes to increase and enhance roosting habitat for

vespertilionid bat species and temperature and humidity logger data loggers to

monitor microclimate within the undercroft post-grille installation. The primary

objectives of the works were as follows:

To prevent further disturbance and potential for killing or injury of lesser

horseshoe bats and Myotis bats within a well-monitored hibernation site as

well as damage to the roost site itself;

To prevent further damage and vandalism to the Cathedral undercroft. The

undercroft forms part of the monastic buildings of the Cathedral priory and is

designated as a Scheduled Ancient Monument (County Monument Number

263). Moreover the buildings are also listed as Grade II*;

To enable safe scientific monitoring of the bat populations roosting within the

undercroft throughout the year and contribute to knowledge of lesser

horseshoe bat roosting ecology via submitted records.

2.2 Consideration of alternatives

A variety of alternative options have been implemented in order to try and prevent

further unauthorised access to the Cathedral undercroft and associated bat

hibernation roost. These have included the use of spiked metal railings and anti-

climb paint. However, to date none of these measures has resulted in any reduction

in entry to the undercroft by unauthorised persons, which has been continuing for a

period of more than 20 years. Indeed these persons have gone to considerable

lengths including use of crow-bars to bend metal railings and complete removal of

individual spikes in order to continue to gain access and sleep rough in the

undercroft.

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3 Worcestershire Bat Group Monitoring and Protection of Lesser Horseshoe Bats Worcester Cathedral Undercroft, Worcester

2.3 Requirement for licensing

Discussions were held with representatives from Natural England’s licensing team

and it was determined that the installation of the grilles would constitute an alteration

to the access point used by bats returning to roost within the Cathedral undercroft.

For this reason and to ensure full compliance with the strict UK and European law

affecting bats it was considered appropriate to pursue a Natural England

conservation licence to cover the activities proposed.

There may also be an element of disturbance as part of the installation of the grilles.

Although the lesser horseshoe bats have not been so far recorded using the

undercroft as a summer roost site it is possible that both individuals of lesser

horseshoe bats and vespertilionid species might use the site for night roosting and

as occasional day roost.

3.3 Detailed methods

3.3.1 Timing of works

Works were completed in September 2013 in order to minimise any risk of disturbing

torpid or hibernating bats. The site is too cool to function as a breeding roost,

although it could be used as an occasional night or day roost by non-breeding

individuals. A pre-start survey was also completed as a further precautionary

measure (see below).

3.3.2 Pre-start survey and inspection

Monitoring of the lesser horseshoe bats was completed prior to and during the

installation of a grilles. Temperatures inside the undercroft were warm (15.6˚C) at

the time of the works and the bats were active and vocalising. No torpid bats were

encountered and no bats were active within the areas of work. Consequently there

was no need to undertake exclusion of physical handling of bats in order to complete

the installation of the grilles.

3.3.3 Installation of the bat grille

The design of the bat grille was been drawn up with reference to the guidelines of

Natural England and with specialist input from Dr Roger Ransome (50 + years

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4 Worcestershire Bat Group Monitoring and Protection of Lesser Horseshoe Bats Worcester Cathedral Undercroft, Worcester

experience of working with lesser horseshoe bats and designer of many bat grilles),

Dr Henry Schofield (Vincent Wildlife Trust and author of ‘The Lesser Horseshoe Bat

Conservation Manual’) and Mr Colin Morris (also of VWT and an expert on lesser

horseshoe bats and roost design).

Before contractors commenced site works the licensed ecologist provided a ‘tool-box

talk’ to illustrate the normal roosting behaviour of the bats, explained the requirement

to minimise noise and unnecessary disturbance and to confirm the appropriate

course of action to be followed in the unlikely event that bats were encountered

during the course of the installation of the grille (see below).

The licensed ecologist was on site during the initial set up of the grille on site and

maintained a ‘watching brief’ thereafter to assist or provide advice on any specific

aspects of the works.

A total of 8 lesser horseshoe bats were present at the time of the works, positioned

at the very back of the cathedral undercroft and apparently unaffected by the works

to install the grilles.

3.4 Location, number and species of bats involved

The majority of the bats which have been recorded roosting in the undercroft are

lesser horseshoe bats, which are typically found hanging from the vaulted brick

ceiling at the furthest point away from the entrance of the undercroft (see appended

plans and photographs). The precise number of individuals typically varies from

month to month in the range 3 to 17. The most recent visits in October and

November 2013 (post-grille installation) have recorded 4 and 6 lesser horseshoe

bats in torpor respectively. These numbers are down slightly from the 8 recorded at

the time of the grille installation. However, this is not be regarded as a cause for

concern at this stage as numbers fluctuate from month to month, largely it would

appear in relation to prevailing weather conditions and temperatures. Ongoing

monthly monitoring is planned for the winter of 2013/2014 during which time it is

hoped that the lesser horseshoe bat numbers will match or exceed those of previous

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5 Worcestershire Bat Group Monitoring and Protection of Lesser Horseshoe Bats Worcester Cathedral Undercroft, Worcester

years. For detailed bat locations please refer to the appended survey sheets which

accompany this project report.

4. WIDER SCIENTIFIC CONTEXT AND FUTURE PROPOSALS

Worcester Bat Group have been undertaking surveys at the Cathedral Undercroft

since 2010 and the intention is to continue to monitor the condition of the site and its

use by bats, in conjunction and agreement with the Cathedral Archaeologist, Mr

Chris Guy. The site provides an excellent potential training resource for new bat

surveyors as well as more experienced surveyors wishing to gain experience of bats

in hibernation and work towards a science and conservation licence. In all cases

current monitoring of the site has been undertaken by experienced and appropriately

licensed ecologists within the group, working with great sensitivity and using

restricted numbers of additional surveyors.

Future outstanding works to be completed at this site include the installation of a

number of crevice boxes and data-loggers, kindly donated by BCT and secured by

Mr Colin Cross of WBG. Due to the status of the undercroft as a Scheduled Ancient

Monument it will not be possible to use permanent fixings such as nails, screws etc

to secure the boxes. However, the availability of alcoves and niches mean that it

should still be possible to secure the boxes and dataloggers without damaging the

structure of the undercroft.

The other key action that remains outstanding at the undercroft is the clearing away

of rubbish and bedding materials associated with the former unauthorised use of the

undercroft by rough sleepers/drinkers/drug-takers. It has been agreed that WBG

would assist the cathedral staff with this process after the bats have left the site

again in the spring/summer of 2014 (as informed by monthly monitoring inspections).

This will significantly improve the visual appeal of the undercroft as well as its safety

for future monitoring and use by authorised cathedral archaeological staff.

It is not currently known where the lesser horseshoe bats roosting in the undercroft

move to in the summer months, but the presence of a maternity roost somewhere

within the Cathedral complex is strongly suspected. A small breeding colony of

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6 Worcestershire Bat Group Monitoring and Protection of Lesser Horseshoe Bats Worcester Cathedral Undercroft, Worcester

lesser horseshoe bats was identified in the roof spaces of the Bishops Palace by

Focus Ecology Ltd in July 2013 and appropriate advice has been provided to the

managers of the property. Future scientific study opportunities around the cathedral

environs may include the use of radio-tagging and bat activity surveys to confirm the

location of lesser horseshoe bat summer roosts and appropriate protection of these

sites when identified. Such a study is something that the Worcester Bat Group might

wish to implement in the future under an appropriate licence from Natural England

but would obviously require further discussion and full agreement of the relevant

landowners.

It is anticipated that there will be obvious benefits to the ‘favourable conservation

status’ of the lesser horseshoe bats utilising the Cathedral from completion of the

grilles. The most obvious of these is the protection that the grille will afford to

roosting bats through prevention of further unwanted disturbance by rough sleepers.

Candles have been found in the undercroft on numerous occasions and the potential

for accidental fires or even direct collision between roosting lesser horseshoe bats

(many of which roost at head/shoulder height within the undercroft) is obvious unless

the site is properly protected as has been achieved here.

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7 Worcestershire Bat Group Monitoring and Protection of Lesser Horseshoe Bats Worcester Cathedral Undercroft, Worcester

5 PHOTOGRAPHS

Plate 1: view of lesser horseshoe bats roosting

within undercroft.

Plate 2: bed, candles and drinks cans within

undercroft.

Plate 3: more evidence of rough sleeping within

undercroft.

Plate 4: view damaging railings where unauthorised

access has occurred to undercroft.

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8 Worcestershire Bat Group Monitoring and Protection of Lesser Horseshoe Bats Worcester Cathedral Undercroft, Worcester

Plate 5: view of workforce completing grille

installation.

Plate 6: view of completed grilles under arches

of the cathedral undrcroft.

Plate 7: completed grille under archway.

Plate 8: Lesser horseshoe bat hanging from small

masonry crevice (14.11.2013).

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9 Worcestershire Bat Group Monitoring and Protection of Lesser Horseshoe Bats Worcester Cathedral Undercroft, Worcester

6 MONITORING RESULTS (2011 - 2013)

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2011Month Peak Count (LHS) Temp (˚C) Relative humidity (%)

November 11 N/A 73%

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2012Month Peak Count (LHS) Internal Temp (˚C) Relative humidity (%)

January (early) 11 9.5 80

January (late) 10 7.5 85

May 3 15.5 77

June 1 17 82

July 0 18.5 73

November 4 8 N/A

December 7 8.5 N/A

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2013Month Peak Count (LHS) Internal Temp (˚C) Relative humidity (%)

January 10 7.5 81.5

February 9 11.5 62

April 4 14 (external) N/A

September 8 15.6 83.7

October 4 16.7 79

November 6 14.1 72

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13 Worcestershire Bat Group Monitoring and Protection of Lesser Horseshoe Bats Worcester Cathedral Undercroft, Worcester

8 CONSTRUCTION PLANS

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Worcester CathedralReredorter Ruins

CHRIS

ROMAIN

ARCHITECTURE

45 SALISBURY ROAD,FORDINGBRIDGESP6 1EHTEL 01 425 650980FAX 01 425 [email protected]

Proposed Grilles and Fences

July 2011

PROJECT:

DRAWING:

SCALE:DATE:

JOB No:

DWG No: REV:03C06G14

1:100

A

ALL EXCAVATIONS BYCATHEDRAL ARCHAEOLOGIST

1350mm high railingsaround top of stairwell

buttress

arch

up

steps

arch

UNDERCROFT BELOW

steps

existingbrick wall

1350mm high railingsaround top of stairwell

roof level above ruins

approx level of undercroft floor

approx ground level

Elevation Looking North

Plan

brick wall

tree

2.4 m high security fence with20mm dia bars with blunt pointsand 40 x 15 rails finished inblack enamel: posts at 2.4m centres concreted into ground

2.4 m high security fence with20mm dia bars with blunt pointsand 40 x 15 rails finished inblack enamel: posts at 2.4m centres concreted into ground

removetree (byService Dept)

arch arch

build up stone wall to insideface of arch(stonework byWorks Dept)

Infill to arches:20mm dia. ms horizontal bars at 150mm ctrswith 50 x 20 verticals: 1No. screen incorporatingside hung door with heavy duty high security lockAll steelwork finished in black enamel

accessgate

tree

retain existing fence retain /repair existing fence

A B C

A B C

D

E

ED

buttress buttress buttress

0 5m

scale 1:100 at A3

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Worcester CathedralReredorter Ruins

CHRIS

ROMAIN

ARCHITECTURE

45 SALISBURY ROAD,FORDINGBRIDGESP6 1EHTEL 01 425 650980FAX 01 425 [email protected]

Proposed Grilles

July 2011

PROJECT:

DRAWING:

SCALE:DATE:

JOB No:

DWG No: REV:03C06G14

1:40

stone arch

grille butressretain existing railings

approx ground level

250 wide sawn andrubbed Hollington redsanndstone stone dwarf wallby Cathedral Works Dept:150 x 250 limecrete foundation(1 part hydraulic lime NHL 3.5:3 parts mixed aggregate)

20mm dia. horizontalbars at 150mm ctrs50 x 18mm verticals and top/bottom railsResin anchor fixings into stone joints

38 x 38 RHS postswith 150 x 150 x 6fixing plates withresin anchors intobrickwork

railings to 3 sides of lightwell

2.4 m high security fence with20mm dia bars with blunt pointsand 40 x 15 rails finished inblack enamel: posts at 2.4m centres concreted into groundin footings excavated by handby the Cathedral Archaeologist

ALL STEELWORK TO BE GALVANISED AFTER MANUFACTUREWITH CALCIUM PLUMBATE OR OTHER APPROVED PRIMER AND 2 COATS BALCK ENAMEL PAINT

C

500 x 500 x800 deep footings for concrete to postsat approx 1800mm ctrsEXCAVATION BYCATHEDRAL ARCHAEOLOGIST

500 x 500 x800 deep footings for concrete to postsat approx 1800mm ctrsEXCAVATION BYCATHEDRAL ARCHAEOLOGIST

2520

5370

ED

A B C

0 5m

scale 1:40 at A3

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16 Worcestershire Bat Group Monitoring and Protection of Lesser Horseshoe Bats Worcester Cathedral Undercroft, Worcester

QUALIFICATIONS & EXPERIENCE

Graham Davison - BSc (Hons) MSc MIEEM MSB

Graham is a Senior Ecologist and joint Director of Focus Ecology Ltd with over 10 year’s

worth of experience in the field of applied ecology. He holds a BSc (Hons) degree in

Zoology and an MSc with distinction in Law and Environmental Science. His ecological

experience includes surveys to identify nationally and locally important sites for wildlife,

ecological services to local planning authorities and provision of ecological reports to

accompany major infrastructure projects, housing schemes, industrial developments and

mineral extraction. Graham is a competent botanical surveyor and has considerable

expertise in protected species surveys, holding protected species licenses for bats, great

crested newts, white-clawed crayfish, and barn owls as well as competency in the survey

of badgers, reptiles, otter, water vole, breeding and over-wintering birds. Graham is

skilled in the production of reports and Nature Conservation Management Plans

providing advice to ensure legal compliance and consistency with recognised best

practice.

Jane Sedgeley – PhD BA (Hons) MIEEM

Jane is an ecologist with more than 20 year’s experience in ecological research and applied ecology. She holds a PhD in Zoology, specialising in roosting ecology of bats and a degree in Ecology. She is a full member of the Institute of Ecology and Environmental Management. Jane was one of the local coordinators for the Bat Conservation Trust’s Bechstein’s Bat survey and regularly assists Dr Roger Ransome with his long-term studies of breeding and hibernating greater and lesser horseshoe bats in Gloucestershire. Jane is currently working for the Vincent Wildlife Trust as a project officer promoting conservation of lesser horseshoe bats in Brecon Beacon’s National Park. If necessary, Jane’s NE bat Licence (20114315) allows her to disturb and handle hibernating bats.

Schwegler 2F-DFP Bat Box


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