Field Surveying Techniques
3. Bats
As a flying mammal species, bats can prove to be very difficult to survey in general. They can require the use of specific equipment and normally an excellent knowledge of species-specific frequencies, behaviour, diet and habitat.
Bat detector
One of the most popular surveying techniques involves the use of a bat detector; a detector is able to collect and convert the echolocation signals used by bats to navigate around so that they become audible to humans. A top of the range bat detector can detect all echolocation frequencies from all bat species present in the UK. The use of a bat detector also relies on the user having a good working knowledge of the unique frequencies that each individual species uses to echolocate, though now it is also possible to record the audio and use computer software to analyse the results. Other methods include colony counts; this requires the surveyor to have knowledge of where a roost site is situated and then count all bats emerging from the roost. Any methods involving the catching or handling of bats requires a licensed surveyor and is therefore are not regularly used. There are also some species specific survey methods, for example a waterway survey involves the use of a bat detector along a linear water way such as a river and focuses on Daubenton's bat as they tend to search for invertebrates across the water.
