Southern Scotland Bat Survey, 2016
NatureScot
Description
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.
Geographic Description
Southern Scotland (Dumfries and Galloway; East Ayrshire; East Lothian; East Renfrewshire; Edinburgh; Falkirk; Fife; Midlothian; North Ayrshire; Renfrewshire; Scottish Borders; South Ayrshire; South Lanarkshire; West Lothian)
Purpose
To minimise the impact of future wind farm development on bats, it is necessary to identify key areas for bats. This requires surveys and analyses that are able to provide a robust understanding of large-scale patterns in speciesí distributions and abundance (Pereira & Cooper, 2006; Jones, 2011).
Data quality
At the end of a recording session, the memory card was returned to the British Trust for Ornithology (BTO) for analysis. Semi-automated acoustic identification of bats using an acoustic classifier TADARIDA (a Toolbox for Animal Detection in Acoustic Recordings Integrating Discriminant Analysis; Bas, 2016) was used. For common Pipistrellus pipistrellus and soprano pipistrelle Pipistrellus pygmaeus, which accounted for >95% of all bat recordings made during the survey, TADARIDA identifications of these species for which the estimated probability of correct classification was high (? 0.8), were taken as being accurate. Manual checking of spectrograms using software SonoBat was used as an independent check of the original species identities assigned by the TADARIDA classifier. Manual checks were carried out on a random sample of 1,000 recordings each of common and soprano pipistrelle, to verify that classifier identification of these species was accurate. For the other species, all recordings were inspected with SonoBat regardless of the associated probability of correct classification. Species identities were checked (and re-classified if necessary) based on call parameters defined in Russ (2012) and Barataud (2015). Calls assigned to species whose calls had the most potential to be confused with those of other species (e.g. bats in the genus Myotis and Nyctalus) were re-examined in SonoBat, comparing them to other recordings potentially of the same bat made from the same location on the same night at neighbouring points in time. All subsequent analyses use final identities upon completion of the above inspection and (where necessary) correction steps.
Citation
Newson, S.E., Evans, H.E., Gillings, S., Jarrett, D. & Wilson, M.W. 2017. A survey of high risk bat species across southern Scotland. Scottish Natural Heritage Commissioned Report No. 1008
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Digitised records
Looking up... the number of records that can be accessed through the NBN Atlas. This resource was last checked for updated data on 17 May 2022. The most recent data was published on 17 May 2022.
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