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Ecology and Bat Surveys: What you need to know?

When you embark on your construction project, there may be several site constraints which need further investigation, as they might have an impact on your development scope. One of these is biodiversity and the local ecology.

A place to start would be to arrange a Preliminary Ecological Appraisal which can also be called an Extended Phase I Habitat Survey. This evaluates the existing ecology of the site. It is important to procure a survey or appraisal in advance of a planning application if the proposed development impacts on the local biodiversity. This requirement is usually discussed during pre-application conversations. The National Planning Policy Framework (NPPF) also places an emphasis on avoiding a net loss of biodiversity and achieving net gains for nature.

A Preliminary Ecological Appraisal (PEA) and Preliminary Roost Assessment (PRA) are usually grouped together and carried out at the same time. Summarised, they have several aims:

  1. to identify likely ecological constraints and features of biodiversity value present in and around the development site;

  2. to inform the design of the development such that impacts on features or biodiversity importance can be avoided or minimised;

  3. to inform the scope of any necessary further ecological surveys and assessments that are likely to be required as part of the planning application process.

So, what is included? The assessment will include site surveys (PEA & PRA), desk studies and production of Phase 1 Habitat Map and Report. Broken down, this includes the study of relevant ecological receptor datasets, walkover ecological assessment including protected species audit and habitat mapping, preparation of a PEA report compliant to British Standard 42020:2017 [updated], assessment of problematic species, preliminary bat roost assessment, assessment of bird and barn owl presence and finally preparation of PRA report, compliant to Bat Conservation trust (2016) guidelines. The scope of these works will be dependent on the Ecology Consultant and will be site specific for your scheme.

The survey is intended to provide a baseline assessment of the ecological value and constraints of the site. It may highlight further surveys which will be needed before the project can progress to planning.

Following a PEA and a PRA, if specific issues such as presence of protected species or priority species, further surveys are necessary. For example, if the PRA shows a positive result for presence of bats OR potential roosting location or access points, then emergence/dawn re-entry surveys will be needed. Up to three surveys may be required and these need to be carried out between May to August. You need to plan this in advance and be aware of the seasonal time constraints.

As a core value at Arkhi to build sustainability and sensitively to local ecology, we have collaborated with several Ecological Consultants across the North West and Wales on our client’s behalf. If you would like to find out more or discuss your project with one of the Arkhi team, get in touch on 01260 540170 or drop us an email at

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