Official statistic on bat population trends

This page hosts the Official Statistic ‘Population trends for bat species in the UK’ published on 28 May 2026, including data up to summer 2025.

Official Statistic description

Bat population trends are published as an annual Official Statistic. The Statistic comprises trends of UK bat species based on data gathered through the UK-wide bat monitoring scheme, the National Bat Monitoring Programme (NBMP).

The point of first release for the bat population trends Official Statistic is JNCC’s website. The results of the Statistic are also incorporated into the NBMP Annual Report where they are presented alongside detailed species accounts, and a broader range of bat trends for species and surveys that currently do not meet the qualifying criteria for Official Statistics.

The NBMP is a UK-wide monitoring scheme (running since 1996) consisting of four long-term structured core surveys: Field Survey, Waterway Survey, Roost Count and Hibernation Survey. The Field and Waterway Surveys involve counting specific bat species along defined transects. The Roost Count involves counting bats emerging from summer roosts and the Hibernation Survey involves counting bats present at hibernacula. All surveys are carried out during specified time periods and weather conditions.

The NBMP is run by the Bat Conservation Trust in partnership with the Joint Nature Conservation Committee, and supported and steered by Natural England, Natural Resources Wales, NatureScot and the Northern Ireland Environment Agency. The NBMP is indebted to all volunteers who contribute data to the programme. Bat Conservation Ireland contributes Northern Ireland bat records collated by the Irish Bat Monitoring Programme (funded by the National Parks and Wildlife Service of the Department of Arts, Heritage and the Gaeltacht, Republic of Ireland, and the Northern Ireland Environment Agency).

Top

Scope of the statistics

• Bat population trends are presented at UK, GB and country level for those species where adequate, robust data are available from at least one of the four core surveys up to and including the 2025 field season.
• Trends presented at a GB level cover 11 of the UK’s 17 breeding bat species. This consists of nine individual species and one group of two species (i.e. data on Whiskered Bats and Brandt’s Bats are combined together into a single trend).
• Trends are presented at a country level for 11 species in England, seven species in Wales, four species in Scotland and one species in Northern Ireland.
• UK-level population trends are presented for five species. Long-term trends are presented from 1999 to 2024 (with the Brown Long-eared Bat roost count only from 2001 and Daubenton’s Bat from 2006 due to that being the earliest year with a sufficient sample size from Northern Ireland).
• Short-term trends are presented from 2019 to 2024.
• This year, for the first time, we are reporting a single trend for each species at each geographic scale, as this provides a clearer message on how each species is faring. Where two surveys are considered to provide a robust picture of how a species is faring, the two trends are combined into a single trend for reporting purposes. For species where only one of two survey trends is considered robust, the more robust trend is simply reported. For the two species which are only monitored using one survey method, the trend from that survey is presented as before. In previous years we reported separate trends for each survey on which each species is monitored. These separate survey trends are still provided for information and can be found in the datasheet and NBMP annual report. 

Top

Summary of results

In total, 7,488 sites have been surveyed across all NBMP core surveys (Field Survey, Waterway Survey, Roost Count and Hibernation Survey) since the start of national bat monitoring in 1997. In 2025, 754 NBMP volunteers completed surveys at 1,654 core survey sites.

Bat species for which trends have been published as part of the Official Statistic are listed in Table 1, and the long-term and short-term trends for bat species at GB, UK and country scales are presented in Tables 2 to 7. Note that the geographic range of Serotine and both species of Horseshoe Bat is restricted to England and Wales only, and Noctule is not found in Northern Ireland.

 

Table 1. Bat species for which a population trend was produced at GB, UK and country scale.

Geographic area	Number of species	Bat species
GB	11	Greater Horseshoe Bat, Lesser Horseshoe Bat, Daubenton’s Bat, Whiskered Bat, Brandt’s Bat, Natterer’s Bat, Common Pipistrelle, Soprano Pipistrelle, Serotine, Noctule, Brown Long-eared Bat
England	11	Greater Horseshoe Bat, Lesser Horseshoe Bat, Daubenton’s Bat, Whiskered Bat, Brandt’s Bat, Natterer’s Bat, Common Pipistrelle, Soprano Pipistrelle, Serotine, Noctule, Brown Long-eared Bat
Wales	7	Greater Horseshoe Bat, Lesser Horseshoe Bat, Daubenton’s Bat, Whiskered Bat, Brandt’s Bat, Natterer’s Bat, Brown Long-eared Bat
Scotland	4	Daubenton’s Bat, Natterer’s Bat, Common Pipistrelle, Soprano Pipistrelle
Northern Ireland	1	Daubenton’s Bat
UK	5	Greater Horseshoe Bat, Lesser Horseshoe Bat, Daubenton’s Bat, Serotine, Noctule

 

For GB populations (Table 2), the long-term trends of six bat species (Greater Horseshoe Bat, Lesser Horseshoe Bat, Daubenton’s Bat, Natterer’s Bat, Common Pipistrelle and Soprano Pipistrelle) are considered to have increased; five species (Whiskered/Brandt’s Bat, Serotine, Noctule and Brown Long-eared Bat) are considered stable; and none of the species monitored are considered to have declined since the baseline year of monitoring (1999 for most of the surveys). There is an increasing long-term UK trend (Table 7) for two out of the five species, while the trend for three species is stable.

Short term 5-year GB trends (Table 2) for a number of species are showing some differences. The only increasing short-term trends are for Lesser Horseshoe Bat and Soprano Pipistrelle, with the other trends indicating stability.

Country trends (Tables 3 to 6) illustrate regional differences in bat trends. Comparison of the long-term and short-term trends from the species we have data for at country level (21 species-country pairings in total) reveals that only three trends are significantly positive in both the long-term and short-term: those for Greater Horseshoe and Lesser Horseshoe Bats in Wales, and for Soprano Pipistrelle in Scotland. In nine cases the trend is stable in both the long-term and short-term. Notably, eight of the country-level trends are less positive in the short-term when comparing to the long-term. This is mostly where a long-term increasing trend is stable in the short-term, but two of these are showing a significantly declining short-term trend but a stable long-term trend: Brown Long-eared Bat in Wales and Daubenton’s Bat in Northern Ireland. There are no instances where the short-term trend shows a significant increase with a stable or declining long-term trend.

While it is possible that these short-term trends are reflections of periodic population cycles, the fact that short-term trends are showing fewer significant increases presents the possibility of a recent external pressure or pressures impacting on bat populations. Continued monitoring of trends and research are vital to provide evidence of the causes behind any changes in trends so that effective recovery measures can be actioned for this specialised group of slow-breeding mammals.

 

Table 2. Population trends of bat species in Great Britain in the short-term (2019–2024) and long-term (1999–2024).

Species	Survey data included in trend	Short-term trend: Average sites per year	Short- term trend (%)	Long-term trend: Average sites per year	Long- term trend (%)
Greater Horseshoe Bat	Hibernation Survey & Roost Count	124	7.1	139	221.5*
Lesser Horseshoe Bat	Hibernation Survey & Roost Count	259	8.9*	299	130.7*
Daubenton's Bat	Hibernation Survey & Waterway Survey	508	3.2	503	16*
Whiskered/Brandt's Bat	Hibernation Survey	161	0.3	161	24.9
Natterer's Bat	Hibernation Survey	307	7.1	309	141.3*
Common Pipistrelle	Field Survey	155	-0.2	168	78.2*
Soprano Pipistrelle	Field Survey	155	44*	168	82.4*
Serotine	Field Survey & Roost Count	150	3	160	6.6
Noctule	Field Survey	155	1.3	168	26.4
Brown Long-eared Bat	Hibernation Survey & Roost Count	290	1.7	329	5.5

Trend is indicated as percentage change over the specified periods.

* = statistically significant change.

 

Table 3. Population trends of bat species in England in the short-term (2019–2024) and long-term (1999–2024).

Species	Survey type	Short-term trend: Average sites per year	Short- term trend (%)	Long-term trend: Average sites per year	Long- term trend (%)
Greater Horseshoe Bat	Hibernation Survey & Roost Count	67	-5	79	192.2*
Lesser Horseshoe Bat	Hibernation Survey & Roost Count	102	-6.5	120	99.3*
Daubenton's Bat	Hibernation Survey & Waterway Survey	361	3.8	394	13.8*
Whiskered/Brandt's Bat	Hibernation Survey	102	3	109	37.6
Natterer's Bat	Hibernation Survey	225	11.3	229	175.2*
Common Pipistrelle	Field Survey	141	0.8	146	86.9*
Soprano Pipistrelle	Field Survey	141	12.8	146	26.2
Serotine	Field Survey & Roost Count	144	5.2	153	5.7
Noctule	Field Survey	141	5.1	146	7.6
Brown Long-eared Bat	Hibernation Survey & Roost Count	221	-2.9	259	-7.8

Trend is indicated as percentage change over the specified periods.

• = statistically significant change.

 

Table 4. Population trends of bat species in Wales in the short-term (2019–2024) and long-term (1999–2024).

Species	Survey type	Short-term trend: Average sites per year	Short- term trend (%)	Long-term trend: Average sites per year	Long- term trend (%)
Greater Horseshoe Bat	Hibernation Survey	62	140.9*	58	437.6*
Lesser Horseshoe Bat	Hibernation Survey & Roost Count	157	13.9*	178	143.4*
Daubenton's Bat	Hibernation Survey	59	14.3	56	42.2
Whiskered/Brandt's Bat	Hibernation Survey	53	-19.4	47	-25.5
Natterer's Bat	Hibernation Survey	73	13.1	71	107.7*
Brown Long-eared Bat	Hibernation Survey	58	-53.5*	52	-29.2

Trend is indicated as percentage change over the specified periods.

* = statistically significant change.

 

Table 5. Population trends of bat species in Scotland in the short-term (2019–2024) and long-term (1999–2024).

Species	Survey type	Short-term trend: Average sites per year	Short- term trend (%)	Long-term trend: Average sites per year	Long- term trend (%)
Daubenton's Bat	Waterway Survey	33	-7.3	32	9.4
Natterer’s Bat	Hibernation Survey	N/a	N/a	12	-13.9
Common Pipistrelle	Field Survey	10	-9.8	16	51
Soprano Pipistrelle	Field Survey	10	86.9*	16	272.4*

Trend is indicated as percentage change over the specified periods.

* = statistically significant change.

 

Table 6. Population trends of bat species in Northern Ireland in the short-term (2019–2024) and long-term (1999–2024).

Species	Survey type	Short-term trend: Average sites per year	Short- term trend (%)	Long-term trend: Average sites per year	Long- term trend (%)
Daubenton's Bat	Waterway Survey	29	-20.3*	26	0.8

Trend is indicated as percentage change over the specified periods.

* = statistically significant change.

 

Table 7. Population trends of bat species in the UK in the short-term (2019–2024) and long-term (1999–2024).

Species	Survey type	Short-term trend: Average sites per year	Short- term trend (%)	Long-term trend: Average sites per year	Long- term trend  (%)
Greater Horseshoe Bat	Hibernation Survey & Roost Count	124	7.1	139	221.5*
Lesser Horseshoe Bat	Hibernation Survey & Roost Count	259	8.9*	299	130.7*
Daubenton’s Bat	Waterway Survey	264	-4	264	2.8
Serotine	Field Survey & Roost Count	150	3	160	6.6
Noctule	Field Survey	155	1.3	168	26.4

Trend is indicated as percentage change over the specified periods.

* = statistically significant change.

Top

Confidence in results, quality assurance and caveats

NBMP volunteers follow standardised, peer-reviewed methods, and the submitted data undergo a combination of automated and manual validation and verification processes. These measures ensure that results derived from these data are scientifically robust.

Bat species differ in their biology and habitat choice, and so a range of survey types are required to ensure effective monitoring of each. The four long-term structured surveys in the NBMP are designed to achieve this. Most species are monitored by more than one of these surveys; the trends from which are combined in the statistics presented above.

The statistical significance of trends is assessed and significant results are clearly presented. Confidence intervals for the indices are presented in the dataset accompanying this statistical release. Only the trends considered to be robust and unbiased are presented as part of the Official Statistic.

Several factors can influence the number of bats or levels of bat activity at the site, and hence impact on the trends. These include temperature, weather conditions and site characteristics; or the ability to detect and identify the species present, such as bat detector model used and the volunteer’s level of skill and experience. These metadata are incorporated into the trend analysis as covariates.

At present we are not able to produce population trends for some of the rarer bat species that are difficult to monitor or rarely encountered (including Bechstein’s Bat, Barbastelle, Grey Long-eared Bat), as data available for them are currently insufficient to allow the calculation of population trends.

Roost counts can be an effective way of monitoring a population in situations where a high proportion of existing roosts are counted and when the species tends to be faithful to its roost site between years. This is the case for species such as Greater and Lesser Horseshoe Bats, for which the roost count produces robust trends.

Some species, such as Common and Soprano Pipistrelle, and potentially also Natterer’s Bat, switch and/or split roosts frequently, often for long periods of time. Roost counts are not considered a suitable metric to estimate population trends for these species because the high instance of roost switching behaviour creates a strong negative bias rendering any trend unreliable. As a result, trends produced from roost counts of these species are not included within the Official Statistic, with the population trends drawn only from other surveys.

Top

Drivers of change

A recent evidence review (Browning et al. 2021) suggests that two factors have had a positive impact on bat population trends: a reduction in human disturbance (following strict legal protection), and a milder climate, in particular over winter and spring, which has been shown to benefit Horseshoe Bat species. The impact of climate change on other UK bat species is less clear.

Prior to 1999 (the baseline year for most of the population trends), it is generally considered that bat populations had been declining since at least the start of the 20th century – recent genetic studies suggest a much longer period of decline for some species. These declines have been attributed to agricultural intensification, loss of roosting and foraging habitat, persecution, pesticides including the use of toxic timber treatments within roosts, water quality, declines in invertebrate prey, development, land-use change and climate change; however, evidence of the drivers of population change in bats is limited.

Bats remain vulnerable to pressures such as landscape change, climate change, development and emerging threats such as new building practices, wind turbines, and light pollution.

The positive and stable trends since the 1990s coincide with the introduction of the current legislation and conservation action to protect and conserve bats. However, the changes suggested by the short-term trends may give new cause for concern.

Top

Background and Methods

Bats have been monitored systematically in the UK since 1997 to assess trends in bat numbers and distribution. The annual NBMP report presents syntheses of results from national bat monitoring as well as other species surveys and research.

Long-term population change is assessed relative to the baseline year of monitoring (for consistency 1999 is generally used as the baseline year since the Field Survey only started in 1998, making the smoothed index value for 1999 a robust baseline value for the majority of species) in comparison to the penultimate year of monitoring (2024). The short-term trends cover the most recent five years up to and including 2024. It is customary to use the smoothed index value from the penultimate year of monitoring for trend assessments as the index value from the most recent year (2025) can change when further years of monitoring data are added.

Because of the inter-species differences in habitat preferences, the NBMP is an integrated programme that uses a number of survey methods, each appropriate for different UK bat species. This approach means that most of the species monitored are surveyed at more than one stage of their annual life cycle

Top

Involvement and contacts

This official statistic was produced by the NBMP partnership to the high professional standards set out in the Code of Practice for Official Statistics, with BCT having primary responsibility for producing the statistic.

Quality Assurance was carried out by BCT and JNCC, and by members of the NBMP scheme steering group representing the Statutory Nature Conservation Bodies.

The population trends are published as a JNCC Official Statistic. If you have any queries, please contact us.

Top

Relation to other Official and National Statistics, and broader relevance

This official statistic forms part of a suite of statistics produced through partnership monitoring schemes as part of JNCC’s terrestrial evidence programme.

The trends feed into the National Statistic Compendium – UK Biodiversity Indicators (including one of the headline indicators on mammals of the wider countryside) as part of measuring progress towards Convention on Biological Diversity targets.

NBMP data contribute to UK reporting on the conservation status of species and feed into country level reporting on Priority Species and biodiversity indicators (e.g. England's 'Status of priority species: relative abundance' statistics). They also feed into conservation assessments such as State of Nature.

Data from the NBMP are used in scientific research and to inform conservation action.

Top