19th May 2022

Britain’s bats edging towards recovery

Hugh Clark

Good news from the darkness today - some of Britain’s bat species are edging towards recovery. The latest long-term survey results released by the National Bat Monitoring Programme (NBMP) show that at least three of Britain’s 17 breeding bat species are showing significant signs of population rise. And another six species or species groups appear stable, according to the latest annual report.

These results reflect relatively recent changes in bat populations, since 1999 for most species. Prior to this, there were historical declines dating back to at least the start of the 20th century.

Kit Stoner, Chief Executive of the Bat Conservation Trust which leads the NBMP, said: “These positive results indicate that strong legal protection works, and conservation action to protect and conserve bats is achieving success. It is vitally important that this continues. Strong wildlife laws and conservation action are underpinning the recovery of charismatic species such as our wonderful common pipistrelle, after decades of historical decline. This means many of us can now enjoy seeing some of these fascinating flying mammals in our parks and green spaces close to where we live. This recovery is not by coincidence but thanks to sustained efforts and it brings us a step closer to achieving our vision of a world richer in wildlife where bats and people thrive together.”

Species on the increase in Britain include the still relatively rare greater horseshoe bat, lesser horseshoe bat and common pipistrelle. In recent years there have been indications that the Natterer’s bat trend is also rising, however it was not possible to update this trend as the Hibernation Survey was suspended in 2020/21.

Species considered stable include Daubenton’s bat, noctule, soprano pipistrelle and brown long-eared bat. However, findings should be treated with caution for some species, in particular, the serotine, which looks stable, but its scarcity during surveys makes population sizes and changes uncertain.

Four survey methods are used to produce long-term trends. Roost counts involve counting bats emerging from summer roosts; hibernation surveys involve counting bats present at hibernacula; field and waterway surveys involve counting certain bat species along defined transect walks. The hibernation survey trends only go up to winter 2019/2020 because the survey was suspended in 2020/21 due to COVID-19.

The NBMP features annual bat surveys undertaken by around a thousand dedicated volunteers each year. In 2021, they gave 11,304 hours of their time and visited 1,202 sites. A further 597 Sunset/Sunrise Surveys were completed by 324 volunteers.

None of the 11 monitored species are considered to have declined significantly since 1999. It is important to remember that we do not have data for all of Britain’s bat species as some are much harder to record reliably in sufficient numbers to yield reliable estimates. This includes habitat specialist species that are likely to be particularly vulnerable to changes in their environment. For some species where a field survey is showing a stable or increasing trend the corresponding roost counts show declines. We believe bat roost switching behaviour skews the counts for these species, and are investigating ways to address this sampling difficulty.

This year, UK trends for only nine species were updated, all of which are considered to be stable or to have increased since monitoring began. Because the Hibernation Survey was suspended due to COVID-19, it has been possible to update only 35 of the usual 57 country-level trends. Long term trends were updated for nine species in England, four species in Scotland, four species in Wales and one in Northern Ireland.

Historical declines in bat populations date back to at least the start of the 20th century and, despite some recovery, numbers are not back to pre-crash levels. One third of Britain’s most highly threatened mammal species are bats. Among these, the International Union for the Conservation of Nature (IUCN) national status for the greater mouse-eared bat remains critically endangered; the grey long-eared bat is endangered; the barbastelle and the serotine are vulnerable. Leisler’s bat and Nathusius’ pipistrelle are classed as near vulnerable.

Bats are the top nocturnal predators of flying insects in Britain. They are long-lived and slow breeding, making them very susceptible to extinction, which is why they are legally protected. The historical declines have been blamed on more intensive farming methods, along with loss of roosting and foraging habitats, persecution, pesticides including the use of toxic timber treatment chemicals within roosts, poor water quality, declines in invertebrate prey groups, development and land-use change. Bats remain vulnerable to pressures such as landscape change, unsympathetic development and emerging threats such as new building practices, climate change, wind turbines, light pollution and any potential detrimental changes to regulations, policies and wildlife laws.


For further information or interview request along please email comms@bats.org.uk. NOTE: Bat images are available from BCT upon request.

The National Bat Monitoring Programme (NBMP) is a world-leading citizen science programme. The results provide valuable indicators of bat population status, change and distribution, which are then used by the Government and conservation bodies to inform conservation efforts and decision making. The NBMP is led by the Bat Conservation Trust, funded by the Joint Nature Conservation Committee and supported and steered by Natural England, Natural Resources Wales, NatureScot and Northern Ireland Environment Agency. Bat Conservation Ireland contributes Northern Ireland bat records collated by the Irish Bat Monitoring Programme, which is funded by the National Parks and Wildlife Service of the Department of Arts, Heritage and the Gaeltacht, Republic of Ireland and Northern Ireland Environment Agency. Data are shared on the National Biodiversity Network (NBN) Atlas and Global Biodiversity Information Facility (GBFI). We are extremely grateful to all the dedicated volunteers who have taken part in the NBMP.

The Bat Conservation Trust (BCT) is the only national organisation solely devoted to the conservation of bats and their habitats in the UK. Its network of 100 local bat groups and more than 1,000 bat workers survey roosts and hibernation sites, and work with householders, builders, farmers and foresters to protect bats. www.bats.org.uk

Joint Nature Conservation Committee (JNCC) is the public body that advises the UK Government and devolved administrations on UK-wide and international nature conservation.

This report should be cited as: Bat Conservation Trust, 2021. The National Bat Monitoring Programme Annual Report 2021. Bat Conservation Trust, London. Available at www.bats.org.uk/our-work/national-bat-monitoring-programme/reports/nbmp-annual-report

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