WORCESTER BAT GROUP PROJECT
Author: Graham Davison
MONITORING AND PROTECTION OF
LESSER HORSESHOE BATS
(RHINOLOPHUS HIPPOSIDEROS):
UNDERCROFT, WORCESTER CATHEDRAL
Date: November 2013
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.
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.
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
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
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
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.
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.
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).
9 Worcestershire Bat Group Monitoring and Protection of Lesser Horseshoe Bats Worcester Cathedral Undercroft, Worcester
6 MONITORING RESULTS (2011 - 2013)
2011Month Peak Count (LHS) Temp (˚C) Relative humidity (%)
November 11 N/A 73%
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
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
13 Worcestershire Bat Group Monitoring and Protection of Lesser Horseshoe Bats Worcester Cathedral Undercroft, Worcester
8 CONSTRUCTION PLANS
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
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
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