ecological surveys

Common Ecological Questions


We know that the ecological survey process can be confusing for people who are looking to start work on a new development project or extension/re-roofing. This can cause frustration and uncertainty as to why certain aspects of the survey process are needed and how it may affect a client’s project, budget, and desired timescales.

To help cut through this and, give you some background and context for the work that we do, we have put together a list of the most common questions we get asked about ecological surveys.

Oak trees


An ecological survey is most often required to support a planning application. The Local Planning Authority (LPA) may ask for this, either once an application has been submitted or as part of their pre-application advice. The aim of the survey is to assess a site for any protected species, to identify important areas of habitat, plants, and animals so that the LPA have the information they need to decide if a development will have a negative impact on wildlife in the area, and what to do to prevent or mitigate this damage.

It is important to remember that it is illegal to disturb or destroy any roosting or nest sites for wildlife. As a result, ecological surveys are often a legal requirement and failure to complete these could be a criminal offence as it means that protected species, such as bats, newts and dormice, and wildlife habitats at a development site could be disturbed or destroyed by the works.

European Kingfisher perched on a branch

Further information about the public’s legal obligations to wildlife is provided by The Wildlife Trust.

However, please rest assured that we do not expect clients to have expertise in this area! Our experienced ecologists would, of course, guide you through the process. We advise our clients on how to meet and even exceed their legal obligations to protect wildlife and maintain or enhance the environment for future generations.

The two most common ecological surveys are:

1) Preliminary Ecological Appraisals (PEAs) of land: These look for potential land to support habitats for a range of species at a site, and inform recommendations for any further, species-specific surveys if required.

PEAs involve visiting the site and collecting data about the features of the land and what habitats might exist there and putting this together with pre-existing data about the species present in the local area. This pre-existing data is retrieved from Local Records Data Centres (LRDCs) and requesting it is known as a ‘data trawl’ or ‘data search’. The LRDCs charge for this service and we invoice their fee to clients at cost price. Once we have completed the site visit and have the data trawl results, we compile our PEA report which sets out our findings and recommendations. This report can be used in support of a planning application and includes an assessment of the flora and fauna and the extent of any further surveys which are needed, if any.

Depending on the size of the site, the site survey element of the PEA usually takes around a half or a full day to complete. The report production element takes significantly longer (it can take up to two weeks to receive the data trawl results!), although this varies based on the size and complexity of the site and we would always provide a tailored quote upon request.

Extended Phase 1 Habitat Survey Bristol - fungi and moss

2) Preliminary Roost Assessments (PRAs) of buildings, trees, and other structures: this type of survey looks at the potential of structures to support bats (either for roosting or hibernation).

A PRA is a daytime inspection where any external walls, attics, roof voids et cetera, are inspected inside and outside to look for evidence of, or potential for, bats. This could include gaps between roof tiles, crevices or any other features which make a building or other structure hospitable for bats. After the inspection has been completed, a report is produced which sets out the level of potential at the site (negligible, low, moderate or high) and makes recommendations for further surveys to assess bat activity, if required.

We provide tailored, fixed costs on request for PEAs and PRAs, and ask that clients provide us with a full site address and any plans or photographs they may have to enable us to do this. For PEAs, we also ask for a red-line boundary plan to ensure that we are clear about the full extent of the area which we need to survey, to make sure that no important areas are missed while we are on site.

Bats found during Bat Survey


The time frame for the survey depends on a number of different factors.

These include:

  • the type of survey e.g. preliminary or follow-up species-specific surveys;
  • how many surveys are required to comply with current guidance;
  • the time of year and whether we need to wait until optimal survey seasons begin before we can proceed; and
  • the size of the development.

Some surveys can be conducted in the course of a few hours or in a day, with the report to follow in around 10-15 working days. However, some surveys, including dusk and dawn activity surveys for bats, can only be conducted at certain times of the year. This can cause delays while we wait for the optimal survey season, meaning some projects can last for weeks or months. However, we would always seek to inform you of any delays at the earliest opportunity and talk you through the options if needed.

Dusk emergence and dawn re-entry surveys for bats are among the most requested surveys that we carry out. Please note that these are seasonally constrained and can only be undertaken from May to August (inclusive). We can carry out the Preliminary Roost Assessment (PRA) at any time of year, but if the potential for bats is found at a site then these dusk and dawn surveys would be needed. We, therefore, recommend that you plan your projects around these time constraints to avoid any disappointment or unnecessary delays to the work.


An ecological report is essentially a detailed document containing everything that the ecologist found on site. It includes an assessment of evidence on, or suitability for, wildlife, plants, and habitats. It will contain details about the number of species present on site, precautionary measures to take if certain species are found during works and mitigation measures to put in place in order to compensate for any loss of habitat. Enhancement measures will also be included to encourage the future use of a site by a range of wildlife and protected species.

Acer Ecology Report


The report is submitted to the planning authorities and enables them to make an assessment about the presence of wildlife at the site and the degree to which it might be impacted if the development were to go ahead. The ecology/ bat survey report, therefore, forms part of the documentary evidence needed by the Local Planning Authorities (LPAs) before they can make their decision on whether to approve a planning application.


The cost of an ecological survey varies depending on the size of the development, the type and number of survey(s) needed, how many surveyors need to attend the site to comply with guidance and how far away it is from our offices/surveyors. It may also increase if we need to use specialist equipment or if reporting will be particularly complex in light of the nature of the development proposals. Given the high degree of variability between projects, we take each request on a case-by-case basis and review the details before arriving at our fixed costing.


If you have any queries relating to your project, or if you would like us to quote for your project, please email us at and provide the site address as well as any site plans and photographs you may have. This will enable us to provide a quote tailored to your site and requirements. We provide fixed fees wherever possible.

If you are interested in finding out more about PEAs and PRAs, why not read our information pages:

If you would like to read more on our Common Questions series, check out these blogs: