National Barbastelle and Bechstein's Bat Survey

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National Barbastelle and Bechstein's Bat Survey Research & Development - Both the Bechstein's and Barbastelle bat are Annex II woodland specialists. Both species are range restricted across England due to their reliance on semi-natural ancient woodland. Bechstein's bats rely on continuous closed canopy woodland with a high density of natural tree holes, often roosting in woodpecker made cavities or natural cavities. Studies to date suggest that woodlands are often greater than 25 hectares and have a high proportion of oak. Although Barbastelles can be found in buildings and other sites, their preferred roosts are in narrow crevices behind loose bark or in tree cavities or splits and so the species is closely associated with old growth woodland where veteran and dead trees are numerous. Even small populations require large numbers of roost trees as the species switches roosts frequently. Roosts have been well documented in a wide range of tree species although oak is used most frequently due to its propensity for developing and retaining preferred roost features. Habitat suitability modelling has taken place for both species in recent years. However, these models are limited as they contain certain biases. They may overestimate the amount of habitat available as they treat all types of broadleaved woodland equally with the exception of ancient woodland. They do not take into account woodland structure or sex-related differences in habitat assemblage. There has never been a national survey undertaken for Barbastelle and the last Bechstein bat national survey was undertaken 15 years ago and it is known that this species range has shifted northwards. It is becoming increasingly important to more accurately map the species range, investigate areas where they could be present as identified through Habitat Suitability Modelling (HSM), to gather data which could provide more accurate woodland occupancy, average roost and colony size information which could then inform population estimates for the species and assist with Favourable Conservation Status (FCS) targets and definitions. Just 2.5% of the UK is covered in ancient woodland, the availability of suitable woodland roosting habitat is likely to be the primary factor limiting the size and distribution of populations. Land use change, urbanisation and light encroachment are thought to have serious detrimental effects on the species as they result in increased habitat fragmentation, loss of foraging and roosting habitat. Critically, ancient woodlands can take multiple centuries to recreate and offer unique and essential habitat. As such habitat cannot be replaced quickly, which places both species at great risk from any activity which impacts on ancient woodland. We need to future proof these species from large scale infrastructure development and urbanisation by understanding where they are, where the most important colonies are and identify opportunities to improve habitat, to improve the future prospects for the species and work towards FCS. By gathering this information we could more accurately inform Nature Recovery Networks (NRN) and Local Nature Recovery Strategies (LNRS) in respect of the species and potentially assist partners to avoid large scale infrastructure projects in areas where such developments could be detrimental to the species.