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Tree Assessment Surveys

 
Tree Assessment

With experience in arboriculture, forestry and ecology the Arborist Support Team can liaise effectively with clients to design effective ecological solutions to arboricultural, forestry and development projects.

The presence of bats in trees often comes into conflict with development and forestry and arboricultural operations, often resulting in the need for some form of risk assessment prior to works, to ensure that no statutory offence is committed.

 
 
Survey Inventory
  • 1. Services Required
  • 2. Background Information
  • 3. Ground Based Assessment
  • 4. Aerial Assessment
  • 5. Nocturnal Surveys
  • 6. Woodlands and Forests
  • 7. Mitigation and Licenses
Services Required

Should you require an assessment of the use of trees by bats, Access Ecology Ltd. are able to offer a full bat support service including:

  • Ground-based visual tree assessment
  • Aerial tree assessment
  • Nocturnal emergence/return survey
  • AnaBat survey of large woodlands and forests
  • Design and implementation of mitigation strategies

Our Arborist Support Team has licenced bat ecologists with NPTC tree climbing certification, LOLER inspected equipment, insurance cover and Health & Safety systems enabling us to work independently of other on-site contractors.  We also have ecologists trained to work on Mobile Elevated Work Platforms (MEWP) should an aerial assessment be required of trees that are unsafe to climb.

Our team has worked throughout the UK with a variety of private clients and public sector bodies on projects ranging from individual trees to whole woodlands. 

We also have licenced barn owl ecologists on the Arborist Support Team and barn owl presence will also be considered throughout any surveys conducted.

Background Information

Britain’s bats are often associated with roosting in buildings.  However, around three quarters of our bat species are known to also or exclusively roost in trees.  Before humans reduced the majority of Britain’s woodland cover, trees provided a major resource of roosting potential. 

Britain’s remaining woodlands and trees are under pressure, yet provide important roosting opportunities for our bats, particularly for those which exclusively or are more commonly associated with trees such as noctule bat, Bechstein’s bat and barbastelle which are also some of our most threatened species.

Bats are notoriously hard to find in trees, where they can roost in a range of suitable features in the trunks and branches of trees including, cracks, crevices, woodpecker holes, hollows and behind loose bark, and often move between suitable features depending upon the season and climatic conditions.  These features are often found in older trees but younger trees should not be discounted as being able to support bats as events such as wind damage or disease can often create suitable roosting features.                 

The presence of bats in trees often comes into conflict with development and forestry and arboricultural operations, often resulting in the need for some form of risk assessment prior to works, to ensure that no statutory offence is committed.

Should you require an assessment of whether bats are roosting in a tree or within woodland or forest, please see the following section for the services our Arborist Support Team can offer.

Ground Based Assessment

Ground-based bat tree inspections are used to make a preliminary appraisal of the potential of bats roosting in a tree or in a woodland.  Our team use endoscopes to inspect suitable bat roosts accessible from ground level and high powered torches and binoculars to assess features higher in the canopy.

Our results are presented in professional reports and plans suitable for planning making recommendations as to further survey works that may be required.  If high risk trees are located, further survey will be recommended in the form of aerial or nocturnal surveys to confirm the roost status of the tree.

Aerial Assessment

Aerial bat tree inspections involve climbing into a tree using ropes and harnesses to inspect features which may support roosting bats.  There are several advantages to using aerial inspections over more conventional nocturnal surveys:

  • Thorough examination of potential bat roost features with endoscopes
  • No need for multiple surveys
  • Fewer ecologists are required to cover the same sample of trees. 
  • Usually more definitive as demonstrating roost absence is more likely
  • Provides an early indication of the presence of a bat roost, negating project schedule delays

As Aerial inspections are the most robust tree risk assessment technique, informed recommendations can be made as to whether works can be carried out on a tree.

Trees are climbed following the Arboricultural Association’s (2006) and the Health & Safety Executive’s (2011; 2011a) guidelines for climbing trees, using appropriate climbing equipment, endoscopes and high powered torches.

Our results are presented in professional reports and plans suitable for submission to a local planning authority identifying bat roost status and recommending mitigation strategies where appropriate. 

Nocturnal Surveys

Nocturnal surveys of trees are an alternative or supplementary technique to aerial inspections and can be more useful at determining numbers and/or species of bats while being the more appropriate technique for trees that are unsafe to aerially inspect.

Using bat detectors and/or night vision equipment, our team collects data on:

  • Species and numbers of bats present
  • Locations of confirmed roosts in the tree
  • Foraging and commuting flight paths of bats

Our results are presented in professional reports and plans suitable for planning confirming presence/absence of a bat roost, roost locations, flight and commuting paths and behaviour and mitigation strategies where appropriate. 

Woodlands and Forests

Large forest and woodland blocks can provide numerous roosting opportunities for bats, and should your development project be likely to affect or remove this habitat it may be necessary to undertake a risk assessment of the proposed works.

Along with ground-based and aerial assessments, Access Ecology are also able to offer an AnaBatTM survey service where these automated bat detectors can be left recording bat echolocation calls in the field for prolonged periods of time.  Using our certified tree-climbing ecologists, the AnaBats can be placed within the forest/woodland canopy to compare data with that collected at ground level. 

As AnaBats can be set up and left in the field for prolonged periods, their use is a cost effective method to survey large areas of forest/woodland.

See our AnaBat section for more information.

Mitigation and Licenses

Any project where bats may be impacted detrimentally will require a Natural England development licence to mitigate these affects on the population. Access Ecology has a number of licenced and experienced staff who have compiled and managed successful licence applications for a range of differing development (and non-development) situations. As a result we are able to offer advice and expertise on all stages of the mitigation process.

Where bat roosts are found in trees and a licence and mitigation strategy is required, our team’s experience in forestry and arboriculture enables us to work effectively with tree work contractors and consultants to devise solutions and suitable methods appropriate to each individual tree.

We are also able to offer advice on the enhancement of sites for bats, as this is becoming particularly important with Local Planning Authorities following Guidance for Public Authorities on Implementing the Biodiversity Duty (Defra, 2006) states,

“It is important that public authorities seek not only to protect important habitats and species, but actively seek opportunities to enhance biodiversity through development proposals, where appropriate. Incorporating enhancement opportunities into projects may help applicants to achieve planning permission”

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