Grey long-eared bat, (c) Daniel Hargreaves
We are lucky to have 18 resident bat species in the UK and they make up almost a quarter of our British mammal species.
Some bats are too rare or elusive to monitor, therefore we only know the population trends for 11 of our 18 species – thanks largely to all the volunteers who support our National Bat Monitoring Programme.
At the national scale, none of the 11 UK bat species we are able to monitor are declining but it is important to put things into context.
The bigger picture: historical declines
Barbastelle - (c) Hugh Clark
It is important to note that UK bat populations have only been monitored for 25 years, a relatively short period of time, and they have experienced huge historical declines. For example, a research paper published by the University of Exeter and BCT in 2023 used genetic techniques to show that one species which remains endangered, the barbastelle, has declined by 99% over several hundred years.
Regional variations and short-term trends
Another crucial detail is that there are regional variations in population trends. In other words, a bat population could be increasing at the national level but decreasing in a specific region. For example, in 2022 data from the National Bat Monitoring Programme (NBMP) suggested that although the common pipistrelle population seemed to be increasing in the UK (since we first started monitoring this species in 1999), there was evidence suggesting the population was decreasing in certain areas in England.
Read the full news piece about this: Local variations in fortunes of common pipistrelle – emerging patterns.
In addition, the NBMP report 2023 examined population trends over a shorter period of five years and there are some worrying signs of change for some of our UK bat populations.
So, are UK bats threatened?
The image shows the International Union for Conservation of Nature (IUCN) Red List Categories which indicate how close a species is to becoming extinct. (c) Sciencia58
A brief overview of how UK bat species are doing:
- Four of the 11 Red Listed British mammals at risk of national extinction are bats.
- The greater mouse-eared bat is Critically Endangered, reduced to two individuals.
- The grey long-eared bat is Endangered.
- The barbastelle and serotine are both Vulnerable.
- The Leisler’s bat and Nathusius’ pipistrelle are both Near Threatened.
- The Bechstein’s bat and the greater horseshoe bat are both Endangered in Wales.
- We have too little data on three further elusive bat species to know how much at risk they are: Alcathoe bat, Brandt’s bat and whiskered bat.
Serotine roosting
