Research commissioned by Scottish Natural Heritage (SNH) and led by the British Trust for Ornithology (BTO) demonstrates the power of volunteers in helping to better understand the distribution of rare and vulnerable bat species.
The Southern Scotland Bat Survey was a pioneering citizen science project run in 2016. It aimed to engage the public by allowing people to borrow bat monitoring equipment for a few days to record bat activity. This approach enables the collection of high-quality data on bats, from a wider range of sites, than could feasibly be achieved by professional researchers alone.
Focusing on the southern third of Scotland, over 1,500 complete nights of bat recording were carried out across 715 one-kilometer squares, resulting in the collection of just under 400,000 bat recordings. Whilst data were collected for all bat species in the region, more detailed analyses were carried out on three species of bats, Leisler’s bat, noctule and Nathusius’ pipistrelle, because their preferred habitat and foraging behaviour make them particularly vulnerable to wind farms. Of the three species, Leisler’s bat and noctule were found to be more widespread and abundant than previously thought, although they remain localised and amongst the five most scarce species of bats in Scotland. Southern Scotland has one of the highest densities of wind farms in the country. The study has produced detailed data and mapping which will be invaluable in assisting decisions in the region, including assessing future onshore wind energy construction.
In order to ensure that the placement of future wind energy developments does not conflict with important areas for bats, surveys and analyses are required to deliver a robust understanding of large-scale patterns in species’ distributions and abundance. We demonstrate that extensive presence-absence survey data can be collected for bats across a large (> 20,000 km2) region of southern Scotland using volunteers supplemented with additional fieldworker effort in remote areas. We advocate a survey design that allows data to be collected for all bat species, but provide more focused analyses on three species (Leisler's bat, noctule and Nathusius' pipistrelle) that are currently considered to be at highest risk from wind turbines. We estimate that between 16% and 24% of the regional populations of these three high risk species overlap existing and approved wind farms, with 50% of this overlap concentrated at just 10% of wind farms. This emphasises the importance of new wind farm placement to minimise impact on these species. We have stratified the region according to the potential impact on bats of future wind farm development, highlighting those areas in the top 1%, 5% and 10% of risk. We conclude that there is a need for higher quality data of this type in order to inform spatial models of bat distribution and activity. As a minimum standard, researchers working on bats should prioritise the collection and use of presence-absence data with consideration of the underlying survey design and representativeness of the data collected. This can be achieved most cost-effectively by working with the public to develop large-scale acoustic monitoring schemes.
Notes
The publication authors are grateful to everyone who took part in the survey, hosted equipment or helped in other ways to make the project so successful. We are particularly grateful to Joe Rayner who gave a huge amount of his own time to design and make equipment that we used in this project, including microphone holders and poles on which microphones were mounted. The Southern Scotland Bat Survey and analyses of these data were commissioned by Scottish Natural Heritage. The authors thank John Calladine, Chris Wernham, Ben Darvill, Alison Johnston, Lindsay Mackinlay, James Pearce-Higgins, Chris Thaxter and Anne Youngman for thier help and support
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