Southern Scotland Bat Survey, 2016

715 different 1 km squares (3.4% of the survey area) were surveyed for bats in 2016. This sample comprised 1,537 complete nights of recording in 1,422 different recording locations. 667,755 recordings were collected which, following analyses and validation, were found to include 399,242 bat recordings.

The ranges occupied by noctule, Leislerís bat and Nathusiusí pipistrelle in southern Scotland are restricted with little overlap between species. For the two Nyctalus species, there is a clear eastñwest split, with Leislerís bat occurring in the west and noctule mainly in the east. For both Leislerís bat and noctule, occupancy and activity patterns were particularly aggregated, with a comparatively small number of 1 km squares contributing a large proportion of the recorded distribution and activity. Nathusiusí pipistrelle was recorded at few sites, dispersed across the survey area, with some clustering of records in the south-west and the north of the region.

Whilst wind farms tend to be located at higher elevation than the three high-risk bat species most commonly occur, there was still significant spatial overlap. Because there is little overlap in the ranges of the three high risk bat species, any steps taken to reduce the risk posed by wind farms at a local scale are most likely to benefit a single species, rather than having broader benefits for the three high risk species.

It is likely that the true population estimates for the two Nyctalus species are likely to far exceed the current published estimates of a few hundred individuals for the whole of Scotland. Considering that the 715 1 km squares surveyed in 2016 comprised just 3.4% of the survey area, and that there were 4,327 recordings of Leislerís bat from 224 1 km squares, and 2,101 recordings of noctule from 152 1 km squares, it is likely that the minimum population sizes of Leislerís bat and noctule for the whole of Scotland are in the thousands. Indications from the survey are that Nathusiusí pipistrelle was much less abundant than the two Nyctalus species in southern Scotland, with just 185 recordings from 23 1 km squares. Considering the migratory status of Nathusiusí pipistrelle it is likely that some records of this species in this survey, particularly at coastal locations, were of migrants. However at one site close to Stranraer (Dumfries and Galloway) in the southwest of the survey area, male advertisement calls were recorded, which may suggest the possibility of breeding in this area. It is expected that the minimum population size of Nathusiusí pipistrelle in Scotland is likely to be in the hundreds.