We have developed an iBats equipment pack for our monitoring teams.

Each pack consists of the following:

1 x Tranquillity bat detector.
1 x Minidisk recorder (plus headphones and leads) or mp3/wav recording device.
1 x GPS/PDA unit - Mio 210, 350 or 360 (plus leads and car attachments).
1 x Petzl head torch.
1 x In/out dual display thermo-hygrometer (plus leads)
1 x 4 way Cigarette socket adaptor.
1 x Car power adaptor.
6 x Sony Hi-MD blank 1GB minidiscs.
2 x 1GB memory cards.
3 x Stereo leads.
32 x Duracell AA batteries
1 x Clipboard and pen
1 x Survey Protocols
1 x Analysis Protocols
1 x Recording sheet
1 x Tuff Zipper Bag. This is the main holder for the pack and all equipment should fit into here.
1 x Bat Detector clamp – this custom made from a Car Window Mount- see below.

We currently order our equipment through Alana Ecology and we get it shipped to each project.

Tranquility detector - how it works

When the detector is switched ON it is ready to receive ultrasound through its microphone. When ultrasound is produced (and the volume is above the threshold of the microphone) the detector is ‘triggered’ and captures a snapshot of the ultrasound. The exact duration of the ultrasound captured depends on the TIME setting on the detector but for this project it is always set at 320ms. This means that when ultrasound is heard the detector will capture 320ms of the ultrasound.

Once the 320ms of ultrasound has been captured, the detector converts the sound into a digital format. This digital format is then slowed down 10 times. Slowing sound down has the effect of lowering the ultrasonic frequencies into audible sound. The resultant audible sound is 10 times longer than the original ultrasound so 320ms becomes 3.2 seconds. The resultant audible sound is output via both the headphone (H/D) and REC sockets of the detector. Once this process is finished the detector is then ready to capture the next set of ultrasound.

For this project we have modified the above approach slightly. A challenge of night time surveying is that there is lots of non-bat ultrasound present e.g. from Orthopterans, vehicles, jangling keys etc. This results in the detector triggering (‘false trigger’) when a bat is not present and causes sampling problems because when the detector is processing ultrasound it is no longer listening for new ultrasound. These ‘false’ triggers means the detector is spending less time surveying for bat ultrasound. To overcome this we set the microphone sensitivity to maximum (using the SENS dial referred to below). The microphone is now so sensitive that it ‘fires’ spontaneously whether ultrasound is present or not. Thus the detector fires for 320ms, processes the sound (if any is present) for 3.2 secs then fires for 320ms and repeats this sequence until the detector is turned off.

This approach means that the survey effect of ‘false’ triggers is removed but means that ultrasound will only be captured if it is present when the detector has ‘fired’ automatically.

Tranquility controls

The tranquility doesn’t have a speaker so headphones are required to hear sounds (alternatively, you could plug a cassette adaptor into the the minidisk headphone/output socket and listen to the calls through the car stereo).

Switches on front of detector

On/Off. Turns the detector on or off.
OK. Green colour indicates detector is switch ON and changes to yellow when batteries need replacing.
DIV. Changes between time expansion of 10 and 32. This should ALWAYS be set to 10.
TIME. The duration of ultrasound that is captured can be set to 40ms, 320ms or 1280ms (1.2 secs). For this project ALWAYS SELECT 320ms.

Switches on rear of detector

REC. Socket for connecting to a recording device.
SENS. Determines how sensitive the microphone is to ultrasound. For this project the SENS knob should be rotated fully clockwise so sensitivity is at maximum.
VOL. Changes the volume of the headphone socket. It DOES NOT change the volume of the REC socket.
H/D. Socket for headphones.
DC. An external 6V battery can be connected to this socket if required.

Minidisk recorder - how it works

Minidisk recorders have not been designed for field use. They are designed for recording and playing music. This means that they are delicate and have many functions that are irrelevant for recording bat calls. Surveyors should go through the manual accompanying the recorder to fully understand all it can do.

The recorder can record in 2 ways – as a normal recorder or in Hi-MD mode. Recordings made in ‘normal’ mode can only be transferred to a computer by playing the recordings via the sound card of the computer. Thus a 2-hour recording will take 2 hours to play into the computer. In Hi-MD mode the recorder can be attached to the computer via the USB socket and copied across as a file. Thus a 2 hour recording will only take a few minutes (depending on computer specifications) to transfer to the computer. For this project it is essential that recording is in Hi-MD mode. The amount of time the recorder can record for can be altered and the Hi-SP recording time must be used in this project.

The recorder needs to be instructed to record in HD-MD and Hi-SP mode. To set the recording mode press NAVI/MENU button for 2 seconds then rotate the jog dial until REC SET flashes. Press the ENTER button and REC MODE should be flashing. Press ENTER button again and rotate the jog dial until HI-SP is flashing. Press the ENTER button and HI-SP mode will be selected.

Recording in Hi-MD mode takes a lot of power and it is essential that a new dry cell battery is used at the start of each survey to ensure recording time is sufficient for the survey. Only Hi-MD discs should be used as ordinary discs cannot record in the proper format for copying to computer.

A head torch is necessary to see the controls at night but be careful not to blind the driver whilst using it! The headphone VOLUME of the recorder should be set to high so that sound can be heard through the headphones. Once the recorder has been set up then the RECORD button should be pressed at the start of the survey. It is important that no other settings are changed on the recorder other than the above.

PDA/GPS - how it works

The PDA/GPS enables geo-referencing of bat encounters and can also help surveyors navigate themselves during the survey. The GPS records its location every 5 seconds and stores it as a file in the PDA. This file can be transferred across to a computer for analysis at a later stage. The GPS also records the time each reading is taken and information on the speed surveyors are travelling. Use of the PDA/GPS, although not absolutely essential for monitoring, adds a lot additional information to the project and lays the foundation for identifying roadside habitats that are beneficial to bat populations.

If digital maps of the survey area are available, they can be imported into the PDA and the position of the surveyor can be seen on the map during the survey. This is useful as it is easy to become lost at night. The PDA has a removable memory card for storing the GPS file and maps. Synchronising the GPS readings and the bat encounters is achieved by simultaneously starting the GPS and the minidisk recorder at the start of the survey. Essentially, if a bat is encountered 50 seconds after the survey start then the location of the GPS at 50 seconds after the start identifies the location.