Since bats are so hard to see at night, there are some technological aids that can help. Information that shows all three possibilities, bat detectors, infrared and night vision, is not easy to find. So I am putting together a simple overview of these technologies to get you started.
Bat detectors use special microphones to listen to the high frequencies of bat sounds, then their electronics convert the high sounds of the bats that we can’t hear to low sounds we can. The frequency of the call can be used to help identify the bats.
A lot of work has been going on in recent years to use computing power to identify bat species from their calls. A researcher at the forefront of this work is Professor Joe Szewczak at Humboldt State University in Northern California. He developed the Sonobat software used by bat researchers and wildlife managers to identify, track, and record bats in locations across the U.S. He is working to make this work on a tablet (and an iPad someday), and I will include that here when I learn about it.
Wildlife Acoustics has created a consumer level bat detector that can be used with your iPad or iPhone, called Echo Meter Touch. This includes a small device that plugs into your iPad or iPhone and has a microphone sensitive to bat frequencies as well as electronics to process that sound for the iPad or iPhone. It costs $399. Dedicated software on your iPad or iPhone then lets you use it. It really is a lot of fun to be outside in the dark and discover that bats are flying near even if you can’t see them.
To see bats, it either has to be light enough for our eyes to see something, or we have to use an aid to “seeing in the dark.” That can be an infrared camera or night vision scopes and goggles.
Infrared (IR) cameras come in two types, active thermal imaging and passive units that need an external IR light source. Active thermal imaging cameras read the infrared light coming from the scene and the subject. With such equipment, you can see the warm and cold patterns of a scene as different colors, and bats will generally show up very differently than the surroundings. FLIR makes some very high-end thermal imaging cameras along with some affordable units. The FLIR C-2 is a compact unit that costs $699, while the FLIR One is a special module that you add to a smart phone or iPad to make it into a thermal imaging unit for $249.
There are also cameras that can capture infrared light that is reflected from a subject from an IR light source. A number of video camera manufacturers include this in certain models as a night vision setting (this is a constantly changing area – in the past, both Panasonic and Sony have made excellent camcorders with night vision, but some of those cameras are now discontinued; Google night vision camcorder). You will need an IR light source for these cameras.
The more powerful the light, the better you will “see” into the dark, especially some distance. Bat Conservation and Management has the brightest, most durable units I have seen. You can also find units from Polaroid at Amazon.com and Cleveland Paranormal sells their own (they also sell IR camcorders).