The Department of Defense (DoD) administers nearly 30 million acres of land for the primary purposes of training troops and testing weapon platforms to ensure military readiness. These inaccessible areas provide large areas of habitat that support significant populations of many threatened, endangered, and at-risk species (TER-S) of bats. Monitoring and managing bat species on many installations is difficult because of the inability to access restricted impact areas on the ground as well as difficulty in sampling at height. To meet stewardship and legal mandates, DoD needs better information about species presence and population trends of TER-S bats on installations, particularly in light of the threat posed by White-Nose Syndrome (WNS). Traditional field sampling has been used successfully on some installations to partially inventory and monitor some bat species in accessible areas. However, significant inaccessible portions of many installations, containing some of the most unique ecosystems, have not been surveyed (e.g., munitions impact areas, live fire areas, and other restricted areas) because they cannot be regularly accessed by field biologists, if at all. While effective in some areas, ground based detectors miss some bats that fly at altitudes above the effective range of the detector and cannot be used to sample bats in inaccessible locations. The objective of this effort is to augment ground-based ultrasonic acoustic sampling approaches in accessible areas, as well as to enable sampling of inaccessible areas on DoD installations with the system we have developed, the Aerial Bat Detection Technology (ABDT).
The Autonomous Aerial Acoustic Recording System was an aerial bird monitoring technology developed and field-tested under ESTCP Project #RC-201112. This project will demonstrate and validate the use of ultrasonic bat detectors on balloons to conduct inventorying of bats at altitude and in inaccessible areas on DoD installations. The system consists of three main components: 1) Micro-processor controlled ultrasonic microphone and recorder; 2) GPS position and altitude tracking and transmission system; and 3) aerial lift vehicle comprised of a helium-filled weather balloon with remote-control capability. The ABDT records bat echolocation calls using an ultrasonic microphone and recorder modified from a commercially available bat detector. Sampling will be done in both tethered mode to allow for sampling above the detection area of ground based detectors, as well as in free flight over inaccessible (i.e., impact) areas. Analysis of recorded echolocation calls will be done using software approved for bat surveys by the US Fish and Wildlife Service. This project will involve use of ultrasonic playback of bat echolocation calls to validate the ability of the system to accurately detect bat echolocation calls. In addition, comparison will be made in free flight between the balloon detector (both tethered and free-flight) and ground based sampling equipment. Finally, costs will be evaluated to show the benefits of sampling with this new technology. Success for the project is made by achieving high detectability in playback tests and improving bat surveys in areas that cannot currently be sampled.
The demonstration and validation of the use of ultrasonic bat detectors to sample bats will improve the inventorying and monitoring of bats in currently inaccessible areas (e.g., at altitude and over impact areas). This project will provide information that will significantly improve DoD’s regulatory compliance. This additional information will become increasingly important as threats from WNS are fully realized. Implementation of the ABDT will allow natural resources staff to document which bat species are present in inaccessible areas, in addition to supplementing data from accessible areas. Documentation of TER-S bats in inaccessible areas, in conjunction with existing data from outside these areas, will provide a significant improvement to our understanding of the role DoD lands play in monitoring important habitats for a variety of TER-S. Furthermore, the training plans with installation environmental staff will put these important tools in the hands of individuals who can best use them.