Orleans House Bat Survey October, 2014

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2 REPORT CONTENTS 1. Introduction 2. Methodology 3. Results 4. Discussion 5. Recommendations 6. Underpinning Legislation and Policy 7. References 8. Appendix Abbreviations: RBAP BAP HAP SAP SNCI SMINC LBG BCT IROPI Richmond Biodiversity Action Plan Biodiversity Action Plan Habitat Action Plan Species Action Plan Site of Nature Conservation Importance Site of Metropolitan Importance for Nature Conservation London Bat Group Bat Conservation Trust Imperative Reasons of Overriding Public Interest Furesfen 1

3 1.0 INTRODUCTION 1.1 PURPOSE Furesfen was asked by Richmond Council to investigate Orleans House, Twickenham TW1 3DJ (TQ169734) for potential bat interest. The survey was carried out by, holder of Class 2 protected species licences, assisted by. The investigation was necessary in order to determine how bats were using the site and if any species might be affected by proposals to remodel the north wing to include: a pitched roof; as well as extend the building north, towards the stables. Some alterations are planned for the west wing, although these are not of a structural nature but will modernise ceiling tiles and insulation materials, whilst allowing for improved ventilation. 1.2 SITE DESCRIPTION Orleans House Gallery houses over four hundred of the boroughs paintings. The facilities are used by community organisations including local schools. The building is set in its own grounds. Orleans House Gardens consist of informal ornamental gardens and a small woodland park containing native broadleaved, European and American tree species. To the north lies an associated stable block, which has been recently refurbished and bat surveys pertaining to the removal of seven trees, were carried out as part of this project (2006). The area is flanked to the south, by the River Thames. 1.3 DESIGNATION Orleans House gardens are noted in the London Ecology Unit Handbook 21 (Archer, 1993), where it is described as a Site of Local Importance for Nature Conservation. The River Thames is a Site of Metropolitan Importance for Nature Conservation (SMINC) and an urban flyway for bird and mammal species traveling into and out of this area of south west London. Bats and broadleaved woodland are target species and habitats within Richmond s Biodiversity Action Plan (BAP). 1.4 NEARBY SITES Marble Hill Park abuts the Orleans House Gardens and the riverfront and is described (Archer, 1993) as a green area flanked by mature horse chestnut trees and some fine oaks and beeches. The Park runs alongside the Thames at Twickenham to Richmond, Furesfen 2

4 where altogether there are three large 18th - 19th century Houses with grounds, all different in nature but amounting to a substantial green influence. 1.5 FEATURES The immediate setting for the Park is characterised in nature conservation terms as: period buildings with large or complex roof voids; broadleaved woodland, some veteran trees and vertical habitats (ivy) within an undisturbed location and in close proximity to open water. Many of the above are features of interest to bats and nine species have been recorded within two kilometres of the site. Trees and tree lines are used by bats in order to commute between features as well as produce and shelter insect biomass upon which they feed. They also create a shield against light ingress, which is a factor for some of the less common bat species. 2.0 METHOD 2.1 DESK STUDY A desk study was undertaken using Authors data and London Bat Group records. 2.2 WALKOVE/EXTERNAL SURVEY A walkover of the area was undertaken , in line with Bat Conservation Trust Guidelines (BCT, 2012) to establish features of bat interest, including any flight lines there might be around the site as well as roost opportunities. This included a binocular inspection of the building during sunny weather at 22 degrees centigrade. An external inspection of some the roof areas and elevations, was undertaken at a later date ( ) using an articulated platform and an endoscope to explore the underside of the soffit running along the north elevation of the west wing. 2.3 INTERNAL SURVEY An internal inspection was undertaken of three voids at the Gallery ( ) although the crawling space was limited. 2.4 BAT EMERGENCE SURVEY A bat emergence and activity survey was performed by two surveyors using hand held, recordable Bat Box 4 Frequency Division equipment and Anabat static recording equipment Recordings were played through BatSound and Analook Furesfen 3

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7 3.3.2 North Wing This section of the building had a flat roof, which could not be seen from the ground. The modern decorative finish around the outside of the upstand was deemed to have no potential for bat interest. An opportunity arose to investigate the roof from a mobile platform during October and subsequent observations were as follows: no animal ingress was noted at the upstand, although the lead flashing was loose at places; at the first floor along the east elevation, were located four windows; both the second and third windows from the Octagon, presented with large gaps in the window heads, suitable for bat ingress; around fifty fresh bat droppings were located up a corner of the sill, thought to pertain to those of pipistrelle bat; although further analysis is required (of the droppings) in order to be certain. Fig.3 The gap at the second window head, Fig. 4 Bat droppings at the corner of the sill 3.4. BAT EMERGENCE SURVEY RESULTS During the emergence surveys, two possibly three species of bat were recorded emerging from the building: Common and Soprano Pipistrelle and Brown Long-eared bat. Four species were recorded during the activity part of the survey (an additional Leisler s bat flew over the site). During the first survey Surveyor 1 identified three bats emerging from two places along the soffit at the west and north end of the west wing. Surveyor 2 identified a pipistrelle bat from the soffit at the corner where the two wings meet. This poorly aligned soffit has been highlighted at Fig.2. During the second survey, only one bat was seen emerging from the building but this time it flew along the roof line and did not echolocate (so could not be identified to species). Furesfen 6

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10 4.0 DISCUSSION 4.1 BAT SPECIES During the surveys four species of bat were recorded: Common and Soprano Pipistrelle, Brown Long-eared and Leisler s Bat. With the exception of the Leisler s bat, three species were roosting at the West Wing of Orleans House and mating roosts are likely due to the number of social calls. There is high fidelity to this building as bats were recorded here during previous survey (Fure, 2006). However there was little fidelity to roost positions and during the two surveys bats emerged from various points along the soffit. During an investigation using an articulated platform, fresh bat droppings revealed an additional roost area along the east elevation of the North Wing. Areas where bats where roosting included: At the soffit behind the downpipe; the western end of the West Wing; above the third row of wall ties at the West Wing ; a hole in the window head at the second window on the first floor of the east elevation of the North Wing; and There is high potential for bat use of the window head at the third window. 4.2 TREES There are two semi-mature trees which will be lost during the current application situated to the north of the North Wing. During the survey it was noted that bats spent a large portion of their evenings foraging around these trees as well as an adjacent yew tree. Trees produce and retain insect biomass on which the bats are foraging. They also create light shields against the uplighters positioned around the elevations of the building. 4.3 LICENCE TEST The Habitats Directive under European Law (see 6.1) states that where a bat is to be disturbed and/or a roost will be destroyed a European Protected Species licence should be obtained. A licence will only be granted provided that certain tests can be met i.e. there are Imperative Reasons of Overriding Public Interest (IROPI). The directive requires competent authorities (Wildlife Licensing at Natural England) to assess the impact of plans or projects. A like for like replacement of ALL features that bats are using should be provided amongst the mitigation measures to be presented to the competent Furesfen 9

11 authority. This includes mitigation for loss of roosts and foraging sites within a credible environment. 4.4 LICENCE APPLICATION Surveys should be undertaken throughout 2015 with a view to executing a derogation licence at the middle to the end of September, 2015 depending on the Method Statement to be produced. The reason for this start date is so that bats will be mobile and their breeding season finished. However it will be before their winter hibernation or the period before they enter torpor. Invasive building works should not take place when bats are hibernating as torpid bats cannot move out of harms way. For this reason soft stripping takes place during the milder autumn weather under the guidance of a Watching Brief performed by a licensed bat ecologist. 4.5 METHOD STATEMENT Method Statements will be required for works at the North Wing. This should detail the process of rebuilding the outer shell wall with a repetitive fault at the window head. This may require a bespoke box which can be procured from various suppliers. Fig. 9 Bat foraging, roosting positions and features of bat interest Furesfen 10

12 4.6 LIGHT POLLUTION The use of light around the elevations is beyond the tolerance of most bat species particularly Brown Long-eared bats (known to be a light shy species) and exceeds BCT and English Nature s guidance (2012, Jones, 2000). Some compromise will be required so that the environment provided for future bat use is credible. It was noted that the elevations used by bats were considered suboptimal (especially the north elevation) as the darkest areas were selected. Light also has a detrimental effect on insect prey species. As the wavelength of light decreases, the attractiveness to insects increases. As low pressure sodium light has wave lengths in the region of 555nm, it does not attract insects. High pressure sodium does attract some insects but on average 57% fewer insects than a Mercury vapour light source. This can lead to demographic insect losses and a third of the insects that fly around light will damage themselves or die leaving less prey for foraging bats (Eisenbeis, 2006; Bruce White and Shardlow, 2011). 4.7 BAT CONSERVATION TRUST GUIDANCE A Statement by the Bat Conservation Trust on Lighting and Mitigation for Bats (May, 2011) resolved that: smarter lighting, rather than less lighting, is key to mitigating the effects of light pollution. Light should only be erected where it is needed, illuminated during the time period it will be used, and at levels that enhance visibility. Any bare bulbs and any light pointing upwards should be eliminated. The spread of light should be kept near to or below the horizontal. Narrow spectrum bulbs should be used to lower the range of species affected by lighting and light sources that emit ultra-violet light must be avoided. Reducing the height of lighting columns as light at a low level reduces ecological impact. 4.8 LIMITATIONS There were a number of limitations to the study which included the lateness of the year. Bat Conservation Trust Guidelines (2012) state that bat surveys should be carried out during the bat breeding season which is June-August. It is therefore not possible to accurately assess the status of the bats found roosting. There is limited crawling space within the shallow void at the West Wing and there are electrical wires covering the floor. During the emergence survey there were problems of access to some areas and glare from uplighters around the building which made it difficult to retain accurate night vision. Furesfen 11

13 The Octagon roof has not been covered during the survey using the articulated platform due to its height. The limitations should be overcome as far as possible during RECOMMENDATIONS Limitations to the surveys, 2014 should be overcome; This may include an articulated platform of sufficient height required to reach the roof of the Octagon (depending on impacts); Three bat surveys are required between June-August, 2015; These surveys should be used to furnish an EPS licence application; An EPS licence application should be made a planning condition; The licence will require the IROPI test to be met; This is the responsibility of the client who will need to complete a Reasoned Statement; The licence will require details of like for like replacement of all the features that the bats are using; Mitigation will also be required including a light curfew at some of the elevations; Replacement of trees should also be considered; Method Statements will be required for works. 6.0 LEGISLATION AND POLICY 6.1 EUROPEAN AND UK LAW PERTAINING TO BATS All species of bat are fully protected under the Wildlife and Countryside Act 1981 (as amended) through their inclusion in Schedule 5. All bats are also included in Schedule 2 of the Conservation (Natural Habitats, & c.) Regulations, The Act and Regulations make it illegal to: intentionally or deliberately kill, injure or capture (take) bats; deliberately disturb bats (whether in a roost or not); damage, destroy or obstruct access to bat roosts; possess or transport a bat or any other part of a bat, unless acquired legally; or sell, barter or exchange bats or parts of bats. Furesfen 12

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15 Loss of hibernation and other seasonally used roost sites; Lack of insect rich feeding habitats such as wetlands, woodlands and grasslands; Losses of linear landscape elements (flight line features) such as tree lines; and Excessive lighting, such as in streets and some open spaces. 6.5 ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION (2009) The Royal Commission on Environmental Pollution, reported on the nuisance caused by badly designed lighting and the effects of artificial light on nature and ecosystems. It concluded that there was an urgent need for government to recognise that artificial light in the wrong place at the wrong time is a pollutant, which can harm the natural environment. 7.0 REFERENCES Archer, J., and Curzon, D., (1993) London Ecology Unit Handbook 21 Author s data Bat Conservation Trust (2012) Bat Survey Guidelines available from Briggs, P.A., Bullock, R. J., Tovey, J., (2007) Ten years of bat monitoring at the WWT London Wetland Centre, compared with National Bat Monitoring Programme trends for Greater London, London Naturalist no 86 London Natural History Society Bruce White, C. and Shardlow, M A review of the impact of artificial light on invertebrates. Buglife; Eisenbeis, G Artificial night lighting and insects: attraction of insects to streetlamps in a rural setting in Germany. In Rich, C. and Longcore, T. eds Ecological consequences of artificial night lighting: Washington, Island Press Fure, A., (2006) Bat Surveys at Orleans House Gardens. Garland L., & Markham S., (2007) Is important bat foraging and commuting habitat legally protected? Jones, J., (2000) Bats and Lighting Guidance, English Nature Mitchell Jones A.J. & McLeish A. P. (Ed s). (2004) Bat workers Manual JNCC Furesfen 14

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17 Bat Emergence Survey Orleans House North and West Wing Twickenham Date: 30/09/14 Sunset: 18:41 Temperature: 18 oc Cloud cover: 0/8 Detector: Bat Box Duet 19:08 Passing Bat Peak frequency 45 KHz, no visual. 19:09 Passing Bat Peak frequency 45 KHz, no visual. 19:13 Passing Bat Peak frequency 45 KHz, no visual. 19:16 Low pass over the north face heading in a northerly direction, no obvious detection on heterodyne detector 19:27- Feeding activity peak frequency 55 KHz 19:31- Feeding activity peak frequency 55 KHz 19:33 Feeding activity peak frequency 45 KHz No obvious emergent activity throughout survey period, though high levels of activity. Fig.11 white arrows indicate bat exit points during first survey (Surveyor 1, ). Furesfen 16