Bat Surveys – Arbor Ecology

UK bats and their roosts are protected under the following National and European legislation:

  • Conservation (Natural habitats, &c.) Regulations 1994 as amended
  • Wildlife and Countryside Act 1981 as amended
  • The Nature Conservation (Scotland) act 2004

Under the above legislation it is an offence to:

  • deliberately or recklessly: capture, injure or kill a bat;
  • disturb bats;
  • obstruct access to a bat roost;
  • damage or destroy a roosting place (even if bats are not occupying the roost at the time); or
  • possess or advertise, sell or exchange a live or dead bat or part of a bat.

Our SNH Licensed Bat Workers are not only Ecologists but Arborists as well, this gives us unrivalled experience when looking for bats in trees. We can prepare full written bat surveys, either Phase 1 ground based habitat surveys or Phase 2 climbed aerial inspections (BS 8596:2015 Surveying for Bats in Trees and Woodland, Bat Conservation Trust (BCT) Bat Surveys for Professional Ecologists – Good Practice Guidelines (3rd Edition, Collins 2016). Bat Tree Habitat Key (Andrews 2013), coupled with entry/emergence watches for nearby built structures. Our extensive arboricultural knowledge of Potential Roosting Features (PRF) in trees allows us to provide a complete bat surveying, reporting and recommendations service.  Where bats are found we can help with mitigation/compensation strategies, including Species Protection Plans and License application to SNH.

We are at the forefront of industry best practice, preferring Aerial Close Visual Inspection (Phase 2) Bat Surveys over activity surveys as a more reliable way of identifying bat roosts in trees. Our ecologists use the latest equipment and climbing techniques to access all parts of the tree which may be in an unsound condition, including Mobile Elevated Work Platforms and Drones with Thermal imaging.

The main advantage of our approach as Arbor Ecologists is that when we have inspected a tree with potential bat roost features and found no bats to be present (where appropriate) we can immediately fell the tree or remove the habitat features using chainsaws, neutralising the tree and preventing their use by bats (or other protected species) in the future. This means that there is no need for a further visit by a licensed bat worker at the time of felling. Being Arbor Ecologists we are able to compensate for the loss of PRF by creating roosting features in nearby trees using chainsaw carving techniques, which saves costs on unsightly bat boxes and reduces environmental impact. Our protected species surveyors are also able to carry out an Arboricultural Constraints Tree Report to BS5837:2012 at the same time as a Phase 1 Ground Based Survey. Having the same team perform both roles saves our clients money and more importantly time – on large developments these savings can be significant. If you need a bat survey, protected species survey or ecology survey please contact us now.

Our Methodology for Bat Surveys

Ground Based Preliminary Roost Assessment: (*Can be included with any tree survey)

Trees are surveyed from ground level, following methods as described in the Bat Conservation Trust (BCT) Bat Surveys for Professional Ecologists – Good Practice Guidelines (3rd Edition, 2016), Section 6.2.4.

The trees are surveyed visually from ground level to canopy top aided by the use of binoculars, high powered torch and digital endoscope. Optimum time for survey is during the winter months when trees are without foliage. These methods are appropriate as they allow the preliminary roost assessment of the bat habitat in the trees to be made with minimum limitation and follow best practice as outlined in the above guidance and BS 8596 Surveying for Bats in Trees and Woodland.

Where potential roosting features are identified from the ground survey, these trees are then recommended for climbed inspection or accessed via MEWP by bat licensed ecologists/arborists with suitable competence certificates and experience. Close visual inspection is carried out on each of the features. Each feature is categorised in line with Bat Surveys for Professional Ecologists: Good Practice Guidelines (3rd edition) and the host tree categorised by its leading feature. *See Aerial Secondary Roost Inspection

Information recorded includes (but is not limited to):

Tree ID Identification number of tree as shown on plan.

Tree tagged with aluminium number tags. as per ‘tree tag’ in tree schedule

Species: Botanical and Common name of species. Where the subgroup was unknown, (Spp) has been used alongside the Genus Age class Young (Y), Early Mature (EM), Mature (M), Late mature (LM) and Veteran (V)

Hgt Height of tree in metres/Height of the PRF in metres.

DBH Diameter Breast Height: trunk diameter in cm measured at 1.5m.

PRF Potential Roosting Feature (at height or ground level)

Crown spread: Average of four measurements taken of North, South, East and West crown spread

Comments: General comments on PRF, condition and form, highlighting any supporting signs of roosting bats.

Recommendations: Recommended further assessment – Aerial PRF inspection, Activity surveys or no further assessment required

Aerial Secondary Roost Inspection: (*May be carried out directly before associated tree works)

 

A pre climb inspection is carried out from ground-level starting at the lower bole upwards to the upper canopy, identifying hazards, work/climbing plan created and risk assessed, all findings are recorded.

Where the tree is safe to climb, a climbing plan/rescue plan is made and communicated to all staff in line with current Health and Safety Executive Regulations and Industry best practice guidelines.

Potential roosting features identified by type, height and orientation and recorded.

The tree is then climbed and top anchor placed, the aerial vantage point will allow the tree to be visually inspected from upper crown to lower bole (top down survey), any further PRF will then be recorded and identified by type, height and orientation.

All features surveyed by using torch and endoscope by suitably trained surveyors.

Evidence from roosting bats (if any) is collected and sent for DNA analysis or photographed in situ.

Where aerial features cannot be fully assessed for their use by bats (due to survey

limitations, equipment or access) activity surveys may be recommended in order to provide more accurate data on how they may be used by bats. Aerial activity surveys may be carried out during dusk or dawn by our climbing arborists reducing the limitations associated to ground based activity surveys in trees.

 

The bats of Scotland:

(we can increase this as time goes by with each project or time we fine one of these species)

There are ten species of bat found in Scotland, they are:

  1. Common Pipistrelle, referred to as  45 kHz Pipistrelle (Pipistrellus pipistrellus),
  2. Soprano Pipistrelle also referred to as 55 kHz Pipistrelle (Pipistrellus pygmaeus)
  3. Nathusius’ Pipistrelle (Pipistrellus nathusii)
  4. Brown Long Eared (Plectus auritus)
  5. Daubenton’s (Myotis daubentonii)
  6. Natterer’s (Myotis nattereri)
  7. Whiskered bat (Myotis mystacinus)
  8. Noctule (Nyctalus noctula)
  9. Leisler’s bat (Nyctalus leisleri)
  10. Brandt’s bat (Myotis brandtii)
  • Bats and the law

 

Legal protection of European protected species

EPS are protected under the Conservation (Natural Habitats, &c.) Regulations 1994 (as amended). In Scotland, regulations 39 and 43 make it an offence, with certain exceptions, to

  1. Deliberately or recklessly: Capture, injure or kill any wild animal of a European protected species;

Harass such an animal or group of animals;

Disturb such an animal while it is rearing or otherwise caring for its young;

Obstruct access to a breeding site or resting place, or otherwise deny the animal use of the breeding site or resting place;

Disturb such an animal while it is occupying a structure or place used for shelter or protection;

Disturb such an animal in a manner that is, or in circumstances which are, likely to significantly affect the local distribution or abundance of the species to which it belongs;

Disturb such an animal in a manner that is, or in circumstances which are, likely to impair its ability to survive, breed or reproduce, or rear or otherwise care for its young.

Disturb such an animal whilst migrating or hibernating.

  1. Deliberately or recklessly to take or destroy the eggs of such an animal;
  1. It is an offence to damage or destroy a breeding site or resting place (note that this applies regardless of whether or not the damage or destruction was carried out deliberately or recklessly);
  1. Deliberately or recklessly disturb any dolphin, porpoise or whale;
  1. Deliberately or recklessly to pick, collect, cut, uproot or destroy a wild plant of a European protected species.
  1. Possess or control, transport, sell or exchange, or offer for sale or exchange, any live or dead animal or plant EPS which has been taken from the wild, or any part of, or anything derived from such an animal or plant.

 

  • Potential tree roost recognition

 

Bats can roost in features as small as a match box, mature trees with multiple features therefor provide excellent roosting opportunities for bats. The older the tree the higher the potential. Different species of tree provide different potential roosting features due to the species specific growth strategy and timber characteristics. For instance, Oak and Scots pine both produce Hazard beams however it is unlikely to find this feature produced in a Sycamore or Beech, fractured branches and tear outs being more common in these species.

Tree Species: (not limited to)

Deciduous: Oak, Ash, Sweet Chestnut, Birch, Beech, Sycamore, Maple, Rowan etc..

Coniferous: Scots Pine, Yew, Juniper, Spruce, Black Pine, Fir spp etc..

Types of Potential Roosting Features (Trees)

  • Bird Box
  • Bat Box
  • Ivy Cover
  • Hazard Beam
  • Decay Hollow
  • Branch Collar Decay Hollow
  • Frost Crack
  • Spiral Crack
  • Dead Wood
  • Basal Decay
  • Tear out
  • Fractured Branch
  • Codominant stem
  • Rubbing Branches
  • Flaking Bark
  • Wood Pecker Holes

Record the data including:

  • Date / Time
  • Grid Reference
  • Tree Tag
  • Species
  • Age
  • Height & Crown spread
  • Position of PRF
  • Type of inspection required (Aerial/Rope and Harness/MEWP)

 

  • Where to go for help

 

Contact Scottish Natural Heritage:

Scottish Natural Heritage Headquarters

Great Glen House
Leachkin Road
Inverness
IV3 8NW

Telephone: 01463 725 000
Email: [email protected]

or the Bat Conservation Trust:

Bat Conservation Trust
5th floor,
Quadrant House,
250 Kennington Lane,
London SE11 5RD
United Kingdom

Bat Helpline 0345 1300 228

Email: enquiri[email protected]

both groups can offer advice on the best procedure dependent on the specific scenario.

 

 

  • Emergency procedures for arborists

 

  • Stop work immediately
  • DO NOT HANDLE BATS – (Bats may bite or scratch. If injury occurs – rinse the injury with running water for 30mins and go directly to the nearest Accident and Emergency.)
  • Contact your Licenced Bat Worker
  • Protect the site from further disturbance

Contact Scottish Natural Heritage

Bat surveys in Scotland.
Ecologist David White points out a bat roost.