My summer research group is trying to discover which species of bat are inhabiting Santa Rosa Island (in the Channel Islands National Park). We are searching for bats using acoustic methods. Our tool of choice is the Anabat ultrasonic bat detector, and we are hoping to get permission from the Channel Islands National Park to place some detectors for long-term monitoring of their bat populations. We’ll use the recordings, hopefully, to identify the species of bat that make Santa Rosa Island home. The tool that we will use for our passive bat detection efforts is the Anabat swift (Titley Scientific, LLC; Columbia, MO). This post describes this detector. The detector specifications (below) show that the unit is small, light, weather hardened, and battery powered. Pictured here with a 12 ounce can of soda (to give you a sense of scale), you can see the detector is about the size of a paperback book. What is pictured is actually the hard, weather-proof case that contains the detector. Sticking up out of the case is a removable omnidirectional microphone. The detector itself is inside the case. Its internal clock is powered by a button battery. It can be made nocturnal. That is, it can be configured to use GPS information to start recording shortly before dusk and stops recording shortly after dawn, going into sleep mode during the day to conserve power. It can be powered by four or eight AA batteries. Below it is pictured with a carriage for four batteries. When placed in the field we will use a carriage for eight AA batteries. Also pictured below is a one (1) meter long cable used to place the omnidirectional microphone at a distance from the detector, a configuration that can be important when recording (i.e., improves the quality of recordings). Also pictured is a simple black webbing strap that can be used to temporarily and non-destructively secure the detector to a post, tree trunk, tree limb, or other stable object. When we use a cable for the microphone, we can use zip-ties or recyclable variations to secure the omnidirectional microphone so that its cone of sensitivity is aimed at spacial volumes where we expect bats to be hunting for food.
We’ve been very pleased with the Swift and the way it has allowed us to record calls over long periods of time. It has slots for two SD cards, allowing for long-term deployment. Our longest deployments have been overnight on the University campus. Depending on the activity on Santa Rosa Island, we hope to be able to deploy for 3-4 weeks before running out of power and space for recordings.