Hibernation Survey

Quality Control

The same survey method is used at hibernation sites each year, and bats are identified by licensed bat workers. The data do not provide a complete picture of bat distribution across hibernation sites, but should be considered as a sample of sites from across the UK. These data are not intended to replace systematic local surveys and data held by local records centres.

Method steps

1. Licensed volunteers identify and survey accessible winter hibernation sites, such as tunnels, caves and mines, and count the number of bats, identifying the species where possible. Typically one survey takes place in January and another survey in February, although counts may also take place in other winter months.

The NBMP hibernation dataset includes records from a sample of hibernation sites across the UK, and is not a complete record of all UK hibernation sites used by bats. There are local gaps in coverage, and some sites have been excluded due to sensitivity issues.