Why do you need a bat survey?
You might be wondering why you even need a bat survey? You've never seen any bats, right? Your planning officer has requested a bat survey is undertaken to support your planning application. Click the following link to view the guidelines most local authorities use to determine if a bat survey is necessary http://www.biodiversityplanningtoolkit.com/bats/bio_bats.html
Some species of bat are very small and only need the tiniest crack or crevice to crawl into. Some don't even need a roof and will happliy make their home under a window sill.
Bats and their roosts are protected under European Law (HM Government Conservation of Habitats and Species Regulations 2010); this means it is illegal to disturb, injure, harm or kill them.
Many bat habitats have been detroyed over the years, including barns, outbuildings, houses and garages and their numbers have declined dramatically. Bats are not pests or rodents! They are the UK's only flying mammal and play a very important part in Britain's wildlife and biodiversity.
Depending on the type of work you wish to undertake and the type of building you wish to modify, your planning officer may require you to have a initial visual assessment. These are sometimes refered to simply as a bat survey, while at other times they can be refered to as a bat and barn owl survey or a bat and nesting birds survey.
All of the above are ultimately the same thing. CEC provides a visual bat and barn owl assessment for your planning application - the barn owl is included because often the type of building requiring this type of survey is an agricultural barn, which could be a suitable habitat for this species (also protected by law). However, if you required a visual survey for a building not suitable for barn owls (i.e. a residential house), then our terminology would change and we would refer to the survey as a bat and nesting bird assessment (nesting birds are also protected by law).