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Climb & Inspect Aerial Tree Surveys: Bats & Barn Owls


Of the seventeen bat species in the UK, thirteen are known to roost in trees. Some bat species rely exclusively on trees for roost sites, whilst others use them for part of the year. All of the UK species forage in woodland and along woodland edges. Any tree can be used as a bat roost and identifying them is not easy, particularly when viewed from the ground.


Barn owls can also be similarly illusive, and are not, as the name suggests restricted to barns! Identifying a barn owl nesting site in a tree can very easily be missed from the ground when a cavity is 8 metres up the stem. Aerial checks of such cavities will provide clear confirmation of their absence or presence.


Just one aerial tree survey can provide accurate presence / likely absence assessments. This may reduce the need of costly dusk and dawn activity surveys (usually at least 3) that are restricted to the bat activity months (i.e. April to October). Aerial tree surveys can be undertaken at any time of year and can substantially reduce waiting times, survey effort, and therefore costs.


Aerial tree surveys are also considered to provide greater rates of success than traditional dusk and dawn activity surveys (In Practice, March 2010).  It is a recognised technique to scope out potential bat roosts as acknowledged by the Bat Conservation trust (BCT).


Aether Ecology has experienced Natural England (NE) and Countryside Council for Wales (CCW) bat licensed workers that are NPTC certified to aerially climb and inspect trees. Initial surveys are undertaken from the ground during a stage 1 approach. Any trees identified as high potential for bats or barn owls may require an aerial tree survey to provide a detailed assessment of the tree.




We produce high quality reports with detailed analysis of the tree and their potential for roosting bats. We will provide recommendations with mitigation and compensation options for any licensable activity that may be required in the future for the relevant SNCO. We also undertake any installation of bat and / or bird boxes at any height as part of the compensation effort.



1: Bats are a Material Consideration!


The National Planning Policy Framework (2012) reminds local planning authorities and developers that important species and habitats (including those in the UK Biodiversity Action Plan and Local Biodiversity Action Plans) occur outside of protected sites and can be a material consideration in planning. Parts of this framework have now been superseded by the Natural Environment and Rural Communities (NERC) Act (2006). This amends the duty on all public bodies to conserve biodiversity and in particular amends the list of species and habitats of principal importance for biodiversity conservation in England and in Wales.


2: How Do I Get the Surveys Done?


Contact us! Or at least contact your local ecologist. Find recognised ecologists in the CIEEM directory in your local area (see USEFUL LINKS). Your friendly ecologist should hold a relevant personal class licence from Natural England or the relevant Statutory Nature Conservation Organisation (SNCO) e.g. Natural Resources Wales to work with specific protected species. Show them your requirements, see what they recommend, ask for their timescale and get a quote! Also ask as many questions as you can, we're here to help conserve our natural environment, but we're also here to help you get through planning!

3: Early Planning is Essential


Things get very busy for ecologist in the summer, so be sure to plan well in advance. Always ask your planning authority if any ecological surveys are required for your development. Far too often this will be red flagged at the 11th hour (often during Autumn), when the survey season has ended. This can cause delays of up to a year, so its well worth thinking ahead! See our WORKS CALENDAR.

4: The Amount of Survey Effort


Depending on the findings of the initial survey, several things may happen. No evidence of bats may be found, and the site may be considered unsuitable for bats and no further survey effort may be required. Alternatively, the site may provide good potential for bats (e.g. good habitat or potential roosting areas), in which case further survey effort is required on a phased approach. If evidence is still not found, then no further work is likely. Finally, if evidence of bats is observed, then a full suite of surveys is recommended as this will probably mean you need to apply for a licence. Essentially, we won't know how much survey effort is truly required until an initial scoping survey has been undertaken, although we can estimate the liklihood based on your site.


5: You Might Need a Licence to Disturb Bats


Due to their level of protection, any form of disturbance to bats, or damage to their roost sites (even if they're not present) may constitute an offence in UK and European law. In order to undertake a development legally, a European Protected Species (EPS) Licence may be necessary to allow otherwise illegal activites to be undertaken. Before an EPS licence can be sought, sufficient survey effort is necessary to understand the types of roost, the number of bats present and the species using the roosts. Sometimes this can take a whole season, or even several seasons to get sufficient information if the roost is large or important (e.g. a maternity roost for rarer species). For more information on licensing, see EUROPEAN PROTECTED SPECIES LICENCES and BAT LOW IMPACT CLASS LICENCES


6: Do I Always Need to Apply for a Licence if I Have Bats?


It depends. Is the development likely to damage, destroy, or obstruct a roost? Will the development disturb, injure or kill bats? If so, then the answer is probably yes, although this is not always the case as there are some exceptional circumstances. However, the works can sometimes be completed by creating an ECOLOGICAL MANAGEMENT PLAN (EMP) where the development can avoid impacting upon bats or bat roosts by the timing of work, and specific precautions that can be put in place. An EMP alone should only be considered once sufficient survey effort has been undertaken and, there will be no conflict with UK and European wildlife law. An EMP cannot be used alone if, for example a roost is being destroyed (e.g. house demolition) or if bats will be actively disturbed (e.g. works can only be done in the bat activity season).


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