The London Bat Group runs a survey with the aim of increasing the network of regularly surveyed sites across London and monitoring more bat species than ever before. We are looking for volunteers with all levels of experience, from beginners who are keen to learn new skills, to more experienced members who can lead the surveys or help with training workshops.

Survey summary

The survey involves walking a roughly triangular transect (divided into twelve stops and walks) within a 1km square and attempting to identify all bat species encountered and counting numbers of bat passes. It is based on BCT’s National Bat Monitoring Programme Field Survey, the main difference being that all species are recorded on all spots and walks (i.e. not just pipistrelles at spots and noctules/serotines on walks, as in the NBMP survey). This expanded survey was successfully trialled during 2008 at RSPB Rainham Marshes and Holland Park, and a very similar methodology has been used with great success for the past 14 years at the London Wetland Centre. The aim is to generate data that can be used to produce population trends for at least seven of London’s eleven bat species (i.e. those that can be identified with reasonable confidence on a bat detector).


We aim to run a number of training workshops in different parts of London. Details of workshops will be made available on the website and in Natterer’s News. If you are unable to attend any of the training workshops then you can still learn by assisting with the surveys. However, attending a workshop is recommended in order to develop your skills more quickly.

How to get involved

We need volunteers to take on the following roles:

  • Expert survey leaders who would like to take on one or more survey squares with the help of survey assistants
  • Survey assistants (all levels of experience welcome) who are keen to accompany a survey leader and develop practical survey skills
  • Training leaders and assistants – if you have specific bat ID, survey skills or training skills and would like to assist with the workshops then please get in touch

To register your interest please contact Philip Briggs at This e-mail address is being protected from spambots. You need JavaScript enabled to view it or on 07952 297996

When to survey

The number of surveys per year is optional, as is the timing of each survey. However it is important that each site is monitored at the same time each year in order to ensure the annual counts are directly comparable. Data from July surveys have the potential to be incorporated into the national species trends produced by the NBMP and therefore contribute to the national as well as the local picture of bat population changes.


On each survey a minimum of two surveyors is needed, each with a bat detector, though only one person needs to be an expert. Bat detectors will be available on loan from London Bat Group.

Selecting a survey site

Ideally the majority of sites should be randomly selected in order to give a more representative picture of trends in London’s bat populations. However a subset of non-random sites is acceptable, e.g. parks and nature reserves that require regular bat surveys in order to inform site management. Surveying the 1km square you live in may be random enough, as the choice of site won’t be based on preconceptions of how many bats are likely to be present (unless that’s why you chose to live there!). It’s important to contact the survey coordinator (details above) about choosing a site, to ensure you don’t survey one that is already being covered.

Mapping the route

A roughly triangular route is mapped out covering a 1km square. Twelve evenly spaced spots are marked out along the route, ideally near landmarks that will be easily located on future surveys. For future reference, draw your route on a map and write down your spot descriptions. Where possible include landscape features that are likely to attract bats, e.g. ponds, rivers and trees. Carry out a daytime recce to ensure that the route is safe and accessible, and make adjustments if not.

Carrying out the survey

Begin the survey 20 minutes after sunset. Record temperature, cloud cover and wind speed. (At the end of the survey record whether it rained at all). Tune one detector to 50 kHz (for smaller bat species) and the other to 25 kHz (for larger species). Start at spot 12 and walk at a moderate pace towards spot 1. When a bat is heard tune the detector up and down in order to hear the call more clearly and identify the species. Species identification tips will be provided. On the survey form record all species heard or seen and the number of passes. A bat pass is a continuous stream of echolocation calls indicating a bat flying past. If constant activity is heard estimate the number of times a bat flies past, or note down as “continuous” if there is too much activity to enable an estimate of number of passes. Passes are counted rather than number of bats as these are easier to estimate. On reaching spot 1 stop for two minutes and again record bat species and number of passes. Then continue to walk your route, counting all bat passes between spots and for two minutes at each spot, until you finish back at spot 12.

Other surveys

Don’t forget there are already some long-running national surveys run as part of the National Bat Monitoring Programme, with several sites occurring within London. These are designed to be as simple as possible while still generating valuable data. We would particularly recommend taking part in the Colony Counts (if you know of bat roosts at which you can do counts) and the Waterway Survey (focusing on Daubenton’s bat) as both are relatively easy to carry out and will provide additional very useful data on bats in London. Contact us for more information on these or go to for more information.

We are also planning to introduce a very simple garden survey. More details to follow.

The London Bat Group runs a survey