14th May 2020
The latest results of the National Bat Monitoring Programme (NBMP) with data up to the end of summer 2019 are now available. Download the report here.
Last year over 1,000 dedicated volunteer citizen scientists carried out NBMP surveys at over 2,000 sites across the UK. The survey results allow BCT to estimate population trends for 11 out of the 17 species of bat which breed in the UK. 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 2019, GB populations of the 11 species of bat surveyed appear to be stable or increasing. A few results need treating with caution 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, Natterer’s bat and common pipistrelle, all of which often use buildings to roosts in. The population trend for Natterer’s bat should be treated with caution until the effect of this species' roost switching behaviour on the Roost Count trend is better understood.
There is also provisional evidence that the population of soprano pipistrelle in Great Britain may have increased in comparison to the baseline year. However, this result should be treated with caution until it has been confirmed by further years of monitoring data.
These encouraging results reflect relatively recent changes in bat populations. It is generally believed that during the early 20th century there were declines in bat populations. Possible drivers of the historical declines include agricultural intensification, loss of roosting and foraging habitat, persecution, pesticides and biocides including the use of toxic timber treatment chemicals within roosts, water quality, declines in insects, unsympathetic development, 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. The International Union for the Conservation of Nature considers nearly 200 bat species to be threatened across the globe, so it’s encouraging to see that in the UK some species appear to be showing signs of recovery thanks to their legal protection and conservation action.
Tomorrow (Friday 15th May) marks the 15th Annual Endangered Species Day so is an ideal time to share some optimism about the potential for species recovery. BCT will certainly continue to raise awareness of bats and their conservation needs to ensure bat populations continue to thrive. BCT is currently exploring and piloting new techniques to monitor population changes in species that are not currently part of the NBMP, including woodland specialists which are likely to be particularly vulnerable to threats such as habitat loss and climate change.
Thank you to Wildlife Acoustics for sponsoring the Field Survey and Waterway Survey.
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 four main surveys - the Field, Waterway and Hibernation Surveys and summer maternity Roost Counts. Most 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 Natural England, Natural Resources Wales, Northern Ireland Environment Agency, and Scottish Natural Heritage. The NBMP is indebted to all volunteers who contribute data to the programme.
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. 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.
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