For planing in advance of wind parks, examining roost usage as well as for many other bat acquisition tasks longterm monitoring is very useful. Usually activity needs to be recorded for a time span of multiple weeks or even months. A technically challenging task.

The box extension for the batcorder simplifies this task. The batcorder is contained within a robust plastic box. The disc-microphone is installed in the box lid and additionally protected by a foam ring. A specifically designed controle module allows connection of 6V to 17 V batteries. The set is sold with a 6V / 12 Ah lead-gel rechargeable battery. This can be recharged using a solar panel (optional). Thus, the maximal runtime of the batcorder is limited only by the SDHC card’s capacity, and is – depending on bat activity – two to six months. There is a box version compatible to batcorder 2.0, 3.0 and 3.1 as well as one without the control module for the  GSM-batcorder.

Reliable monitoring set

The box is based on experiences gained from the wind turbine extension, which is successfully used since 2010. Thus, we added a microphone test to the box extension, to detect deviances from calibrated sensitivity. If the microphone is damaged by rain or dirt, the controle module reports this per SMS.

At the end of each recording interval (night), the box also sends a detailed status update to a freely choosable cell phone number. This message contains the number of recordings of the last night, overall number of recordings, memory capacity of the SDHC card, microphone sensitivity as well as other error conditions like empty battery. All you need is a standard SIM card, which you can install yourself easily. Prerequisite is reasonably well cell coverage at the location.

Reasonable longterm monitoring

Depending on the expected results long term monitoring can be very powerful. Nevertheless some prerequisites at the location are necessary for optimal use of the batcorder. The box should be set up spaced to reflective surfaces above, below, to the sides as well as to the front to reduce echos. If installed on a mast, the box should face away from the main direction of weather to reduce rain exposure of the microphone. Electromagnetic fields (power lines and such) as well as known ultrasound sources (for example ultrasound based humidity sensors) should be avoided. We recommend to test before installation if such sources can not be avoided.

Monitoring for multiple years, as asked for by some officials, is even with state-of-the-art devices not possible without regular maintenance. Microphones age more quickly and should be tested after a year. The device should also be deinstalled before winter to avoid.

Installation and usage

When setting up the box you should always properly fixate the box. At locations with higher visitor rate, the box should be locked and be installed out of easy reach. If installed on a mast we recommend you ask the mast producer, so a technician can do the installation. Some masts are known to be compatible with the box like masts of engineering services- Frey or since 2104 of  energiewerkstatt.

Deployed material and accessories

The standard box extension contains the plastic box including material for attachment of batcorder and control module. The controle module and a 6V / 12 Ah lead-gel battery is included as well. Solar panels are optional.

In addition you need:

• batcorder 2.0, batcorder 3.0 or GSM-batcorder
• SDHC card
• SIM-card for sending SMS messages

When using the GSM-batcorder no control module is necessary and thus not included. The GSM-batcorder has the control module functions implemented.