What is a Bat Detector?

Bat Detector is a slightly misleading term. A bat detector doesn't just tell you there are bats around, it picks up their signals and renders them audible to our ears. Bats in a roost or a nursery can sometimes be heard making squeaking and rustling noises but when they are flying they send out ultrasonic pulses that are too high in frequency for our ears to hear. It is these signals, which tell us so much about the bats, that bat detectors pick up. These are the signals the bats use for navigation and hunting, just like a submarine sonar.

We offer four models of bat detector. At the entry level, the Microbat is a very small and simple detector suitable for children and casual use. It has two frequency ranges enabling it to pick up all the British bat species. It uses the heterodyne principal to make the bat signals audible. (At the time of writing the Microbat was being redesigned - it will reappear in our catalogue as soon as the new model is ready).

The Microbat is ideal for children	Batbox III D is the most popular model and is recommended for most people	The Duet offers a heterodyne receiver and frequency division	The Griffin is the ultimate field tool with built-in solid-state recording

Next is the most popular model for adults and enthusiasts, the Batbox III D. It also uses the heterodyne principle but the central frequency can be varied throughout the whole spectrum used by bats. This makes it more useful for identifying bat species. It also has outputs for headphones and recording. Frequency selection is digital making it easy to select the central frequency accurately.

The Batbox Duet offers two alternative methods of shifting the bat signals into our audio range. It can be used as a heterodyne receiver like the microbat and Batbox III, but also offers frequency division which covers the whole of the bats' spectrum at once. The large LCD back-lit display is extremely accurate and easy to read at all light levels. Frequency amplitude detection allows post-recording computer analysis of sonar peak-frequencies. There is a voice commentary button for annotating recordings.

Whilst the Batbox Duet covers the requirements of most field workers it requires the use of an external recorder if subsequent analysis is to be carried out, or if recordings are needed for later playback. The Batbox Griffin has been designed to provide all the required functions for studying and surveying bat populations, whilst being easy to use in the dark and without the necessity for the usual connecting leads to recording equipment. Recording time is limited only by the capacity of the Compact Flash card used. The advanced design gives the user setup options; its many automatic features allow use by non-specialist operators.

I'm fascinated by the idea of listening to bats but which model should I choose?

• MicroBat - ideal for children and families with a casual interest - simple and lightweight
• Batbox III D - the most popular choice for adults and club enthusiasts - frequency selection makes it easier to identify the type of bat
• Batbox Duet - suitable for field researchers and anyone wanting to explore the bats' world fully - suitable for subsequent analysis by computer
• Batbox Griffin - the ultimate field tool with built-in solid-state recording - for the dedicated professional or anyone who wants the best

Why is it necessary to select the frequency?

The other models can be tuned to any part of the bats' spectrum. This also makes it possible to detect what are the lowest and highest frequencies a particular bat is using, an important aid to identification.

Frequency Division brings all the Bats' spectrum within our range at once, which enables the kind of recordings needed by field workers for subsequent analysis.

What tools are available for analysing bat recordings?

We offer Batscan Software for fast and easy analysis of bat sonar recordings. It is written for Windows and will record and play back sound samples through your windows-compatible sound card. However, a sound card is not necessary in order to analyze and display audio spectrograms.

BatScan processes PCM format digital audio data such as .wav sound files. Default settings have been optimised for use with Batbox Duet.

I've listened to bats around my house but how do I work out what species they are?

Your best guide is the Bat Detective written and produced by Brian Briggs and David King. It consists of a book and CD containing recordings of bat sonar and a description of which bats are making the sound and what it tells us about their behaviour. Here is what A M Hutson, a recognised authority on bats, had to say about the Bat Detective:

"This book, together with the accompanying CD, provides an essential reference for bat enthusiasts who would like to gain or improve their skills in identifying British bats, using a bat detector.

The material has been gathered from experience gained in numerous bat detector workshops, throughout Europe, and is suitable for those who have just acquired a bat detector as well as for more experienced bat workers. The sounds of 13 bat species are included in the 48 tracks of the CD. This is the first ever comprehensive compilation of British bat recordings on compact disc."

We also recommend it for anyone contemplating buying a bat detector as a way of gaining an insight into bat behaviour and the role of the detector.

Would you like to buy a Bat Detector?