3.4 LOC ATION OF KEY SITES AND FEEDING AREAS 37 1 2 3 4 5 6 7 8 9 10 11 Devices that record directly as .WAV files and can be attached to the computer via the USB port have started to appear and these are useful because sound files can be copied across directly to the hard disk of the computer.This approach saves considerable time because recordings will no longer require to be played into the computer via the sound card. Computer sound card No special card is required because standard cards sample at 44 kHz. However it is important that they offer a LINE IN port because there is a growing trend, especially with laptops, for the LINE IN port to be dropped.The user should be able to access the sound card settings to optimise its performance. Appropriate software Software is required to convert sounds into sonograms. As the ultrasound has been converted to audible sound via the detector, sonogram software developed for bird/cetacean sonogram analysis is suitable for bat sonogram analysis. There are many suitable software packages available and some can be downloaded for free from the internet search for bird sound analysis for suitable sites. Useful sonogram analysis tools include a Power spectra function (this identifies which frequency contains the most energy) – filters for cleaning the sonogram and a measuring cursor. ‘BatSound’ is the only sonogram software designed specifically for bat analysis and has all the relevant tools (available from Alana Ecology). Turning a laptop computer into a bat detector with appropriate software, hardware and an ultrasonic microphone it is possible to convert a laptop computer into a bat detector. Although an expensive option the advantage of this system is that high quality sonograms can be produced in the field. Suggested reading Russ (Source C Catto, National Bat Monitoring Programme. Producing sonograms of bat echolocation and social calls is a useful aid to identification. Sonogram analysis is most appropriate for identifying open/edge species with reasonable confidence such as Pipistrellus, Eptesicus, Nyctalus but Rhinolophus and Barbastella species can also be identified. However, separation of Myotis species remains problematic due to the large overlap in call structure of this group. The process of making recordings and producing sonograms is complex and requires some specialised equipment and reasonable computer skills. Mastering the whole process requires a basic understanding of sound theory.