ASSESSING THE CONSISTENCY AND EFFECTIVENSS OF MITIGATION FOR WIND TURBINES PRESCRIBED BY LOCAL PLANNING AUTHORITIES IN THE SOUTH-WEST OF ENGLAND AND ASSESSING THE IMPACTS OF MEDIUM-SCALE WIND TURBINE ELECTRICTY GENERATION ON BAT POPULATIONS.

The impacts of large, offshore wind farms have on bat populations is well documented, with this research informing the Technical Information Notes published by Natural England which are then used to inform planning decisions by Local Planning Authorities. What is unclear, however, is whether the impact these smaller, onshore wind turbines may have can be included in the same category as larger turbines, as is currently the case. This gap in the guidance available has been recognised by Local Planning Authorities, but without the evidence needed to create new guidance documents, Local Planning Authorities must often make decisions using their own discretion; this can lead to inconsistencies between planning applications. In order to test the consistency of the recommendations made by Local Planning Authorities, all of the records pertaining to the development of wind turbines were obtained from the Cornwall County Council online planning portal for a period of 10 years (2001- 2011) and scrutinised, looking at factors including size of the proposed turbine, whether bat surveys had been conducted and whether the application had been accepted or rejected. Recommendations given for two sites with medium-size wind turbines (1 in Devon, 1 in Cornwall) were tested to test how appropriate the mitigation given was; this was achieved by conducting transect surveys over the course of 8 weeks with an aim of mapping bat use of the sites using handheld bat detectors and recording devices. All recordings were analysed using Pettersson Elektronik AB Batsound software. At the site in Devon, spatial analysis of bat use relative to the wind turbine was employed, using a ‘Zone of Influence’ style survey, to determine if bat species may exhibit avoidance of the turbine itself. This was compared between when the turbine was on and when it was off. It was found that a majority of recommendations given by Cornwall County Council in relation to wind turbines pertained to noise and/ or visual impacts, it was only after a development failed to comply with T.I.N. 051/059 that bats were considered. Recommendations relating to bats were shown to vary considerably from site-to-site, but it is concluded that this is preferable to a rigid system, where the individual attributes of each site are not taken into account.It was found that a greater abundance and diversity of bats were found at each site than previous, single-night surveys concluded, leading to the suggestion that single-night surveys may not be sufficient for determining impacts on bat populations. The recommendations given for both sites were deemed to be appropriate. Finally, due to the small repeat number of the surveys, the impact of the turbines on bat behaviour was somewhat inconclusive. There was found to be a significant difference in the numbers of bats between the Zone of Influence and the Adjacent Areas both when the turbine was on and off; meaning that there was consistently a difference in numbers of bats between the two areas regardless of turbine activity. This could be attributed to either an intrinsic avoidance of the turbine itself or a lack of use of the area in general. In P. pipistrellus, however, there was a significant difference between the numbers present in the Adjacent Areas when the turbine was off vs. when it was on, indicating that, if bats do exhibit some avoidance behaviour of the turbine, this species may be more tolerant than others