In 2009 and 2010 Dr Peter Shepherd presented a joint workshop with Judy Stroud of Natural England to the National Bat Conference on factors affecting roost replacement. The workshop presented a review of 300 Natural England EPS licence returns, a review of published studies on roost requirements of UK bat species and guidance that existed at the time. It went on to consider what are the key factors to take account of when designing a replacement roost structure?. Location, structure and temperature regime appear to be issues, with temperature often an overlooked element of roost design and monitoring.
Since the workshop the study by Bristol University on excluding soprano pipistrelles from roosts (Stone et al (2015))¹ has been undertaken indicating that just designing a good replacement does not guarantee use or ‘success’, as in the soprano pipistrelle colonies studied by Stone et al they had suitable roosting alternatives available that were used following exclusion. Bespoke replacement roosts were not provided as part of this study, but the results did indicate that for soprano pipistrelles there appear to be immediately available known alternatives to the main maternity roost. This clearly could affect whether a replacement roost is taken up following exclusion or even at all. However, this does not mean that replacement roosts are not required in order to maintain favourable conservation status of a species. Long term impacts on productivity are unknown and this study can only be applied to soprano pipistrelle. One of the worrying outcomes of the study by Judy Stroud was the absence of a ‘successful’ roost replacement for brown long-eared bats, a species that appears unlike soprano pipistrelle to have a high roost fidelity (Entwhistle et al 2000)². Careful thought is clearly required for this species which is a commonly subject to roost exclusion.