Elekon produce three microphones to be used in conjunction with the Batlogger and Batlogger M models. All microphones are omni-directional; take the temperature measurements and have a frequency range of 10-130kHz:
FG Black: This is the new improved version of the original BL microphone which is relatively insensitive to moisture and humidity. This microphone can be used directly plugged into the Batlogger M or used with an extension cable on the Batlogger.
We find this microphone to be highly sensitive, in some situations this is too sensitive for what is necessary. For example it is great if doing standard emergence/re-entry bat surveys standing still in one place for a length of time or undertaking walks along a hard surface. However, if undertaking field transects through long vegetation or simply moving about a lot this microphone becomes too sensitive (particularly if the settings are not altered from what you would normally use with the BL microphone). We personally keep these microphones purely for when we know that conditions may be a little damp, small enough to carry and easy to replace in the field. A must have for any professional.
FG Green: A highly sensitive microphone to be used with the 100m extension kit and the Batlogger M. We have not had the opportunity to trial this microphone and so cannot state any conclusions, however we believe this microphone to be highly sensitive when considering the length of the extension cable.
BL: This is the original microphone which comes with the Batlogger and Batlogger M as standard. It can be sensitive to moisture or dew in the air and we have had microphones degrade over time after experiencing damp conditions. The microphones do not immediately stop working but rather degrade over a time period which may be a week or so or even several months. Of course, all microphones will degrade over time if placed within damp conditions (although the FG Black has shown considerable resilience to even being placed outside in all weathers). We use this microphone for most survey work as it is highly sensitive and an all-round general microphone suitable for most situations including field transects.
So what about when using the microphones for other survey types such as car transects....
During car transects both the FG Black and the BL microphones perform very well. We use the Elekon 2m extension cable so that the detector can remain safely within the vehicle with just the microphone taped or cable tied to a roof bar etc. In order to help to reduce any wind noise we add a small windshield (acoustic microphone foam cover) over the end of the microphone. In automatic mode the Batlogger and the Batlogger M does not pick up any wind noise using either microphone what so ever and so you only record bat passes, a big plus when it comes to analysing! With the use of the acoustic foam the quality of the sonograms does reduce slightly but this is nothing to be concerned of due to the exceedingly high quality of the sonograms produced from these detectors and species identification is not impaired. A fantastic easy detector with microphone options depending on weather conditions.
It must be remembered that there are many different types of acoustic foam and windshields available. Therefore, denser or more open foams from that which we used may produce differing results. The Elekon 2m extension cable is of high quality and no deterioration to the recordings has been experienced.