17th May 2018

The latest results of the National Bat Monitoring Programme (NBMP) with data up to the end of September 2017 are now available. Download the report here.

Last year nearly 1,000 dedicated volunteers carried out NBMP bat surveys at a total of 1,867 sites across the UK. The survey results allow BCT to provide population trends for 11 out of the 17 species of bat which breed in the UK. Unfortunately, at present we are not able to produce population trends for some of the rarer and more habitat-specialist bat species such as barbastelle or Bechstein’s bat as they are difficult to monitor or rarely encountered.

Results of the NBMP show that from the baseline year of monitoring (1999 for most species) to 2017, GB populations of all 11 species of bat surveyed appear to be either stable or increasing, though a few results need treating with caution at present and there are regional and/or country differences. Species considered to have increased in Great Britain since the baseline year of monitoring are greater horseshoe bat, lesser horseshoe bat and common pipistrelle, all of which often use buildings to roosts in.

As part of the latest species population trend analysis a review was carried out of the methods used to adjust for bias caused by the use of different bat detector models in the Field Survey, since many new models have appeared on the market in recent years. A new approach has now been adopted which accounts better for differences between bat detectors. This has had little impact on the trends for species recorded in the Field Survey, with the exception of soprano pipistrelle; while last year’s NBMP Annual Report and the State of the UK Bats 2017 showed a significant upward trend for soprano pipistrelle, after applying this new approach the species now appears to have a stable trend with no statistically significant increase.

Even though these are positive results, it should be remembered that these trends reflect relatively recent changes to bat populations. It is generally considered that prior to this during the 20th century there were significant declines in bat populations. Possible drivers of these declines that are likely to be relevant historically, currently or in the future include agricultural intensification, loss of roosting and foraging habitat, persecution, pesticides including the use of toxic timber treatment chemicals within roosts, water quality, declines in invertebrate prey groups, development and land-use change and climate change.

The recent positive and stable trends recorded through the NBMP suggests that current legislation and conservation action to protect and conserve bats is being successful, and it is important that this continues. BCT will certainly continue to raise awareness of bats and their conservation needs to ensure bat populations continue to thrive.

To download the latest and previous reports click here.

To find out more about NBMP visit this page.

To find out more about how you can encourage bats in your garden click here.

Editors notes

The NBMP provides statistically robust population trends for 11 of the UK’s 17 breeding bat species. The scheme started in 1996 and has continued gathering data on an annual basis, benefiting from the dedication of thousands of volunteer recorders. The NBMP consists of 4 main surveys - the Field, Waterway and Hibernation Surveys and summer maternity Roost Counts. Some bat species are monitored by more than one survey. Population trends are provided at GB level, and for UK, England, Wales, Scotland and Northern Ireland where possible. The NBMP is run by Bat Conservation Trust, in partnership with the Joint Nature Conservation Committee, and supported and steered by the statutory nature conservation agencies.

Data from the NBMP are used to calculate the bat indicator, one of the UK’s biodiversity headline indicators (http://www.jncc.defra.gov.uk/page-4229). The bat indicator (C8) is a composite index which combines population trend data for eight widespread species. NBMP data are also used to calculate the England bat indicator (https://www.gov.uk/government/statistical-data-sets/env09-england-biodiversity-indicators )

The NBMP is important, not only as the provider of information on bat population trends and status, but also in enabling the UK to meet its obligations under the Habitats Directive, and to report on, implement or deliver country biodiversity strategies, and report to EUROBATS. The current statistical release includes 11 year trend analysis in addition to long term trend analyses (typically since 1999), to enable their use in Habitats Directive Article 17 reporting. A number of collaborative projects are underway which employ NBMP data including projects investigating the effect of annual variation in weather on population trends of UK mammals, birds, and invertebrates; the distribution and spread of Pseudogymnoascus destructans, the fungus responsible for White Nose Syndrome in North American bats, across Europe, Asia and North America; the ecological and human factors impacting woodland bat species’ distributions and assemblages, and how these may change in future climate and land use scenarios; new techniques to enable bats and church congregations to live together.