Department of Defense (DoD) lands house a higher number of listed species than other federal agencies relative to the amount of land they manage. Knowledge of population trends for threatened, endangered, and at-risk species (TER-S) provides useful data in consultation with the U.S. Fish and Wildlife Service, thereby minimizing impacts to the military mission. Numerous techniques are available to conduct population monitoring of TER-S, though many are time consuming and expensive. Some species form colonies in caves, mines, or other structures, including numerous bat species and the Mariana swiftlet (Aerodramus bartschi). Congregations of animals provide an opportunity to efficiently conduct population monitoring efforts. Monitoring of caves, mines, and other structures is often problematic, despite the ease of documenting the initial use of species’ roost sites. Even for sites with small colonies that can be entered and visually counted, the resulting disturbance has been shown to cause site and/or offspring abandonment. As a result, managers initiated monitoring efforts that count animals as they emerge from roost sites, often utilizing night vision equipment, near-infrared cameras, or other special equipment. These techniques provide information on population size but result in subjective counts by human monitors and require extensive time and experience to conduct. The objective of this project is to use automated analysis techniques to improve data quality obtained for these important population surveys.

Technology Description

Advances in videography hardware and automatic processing have enabled the monitoring of wildlife populations. This project will demonstrate and validate the use of thermal videography and automated analysis for censusing bats and birds as they emerge from their roost sites. Data from thermal cameras will be analyzed using a digital image processing (DIP) program developed at the U.S. Army Engineer Research and Development Center to obtain population counts. Three steps constitute the analytical process: target detection, tracking, and counting. The project will validate the ability of the software to accurately perform each step. Software performance will be assessed by comparing the results of the automated analysis to manual observations on short segments of observed thermal data and simulated data. Additionally, the impacts of camera placement will be assessed by setting up the system in a variety of orientations to overcome any masking effects and to further validate previous guidelines associated with camera position. Finally, the cost for each survey method will be calculated to showcase the cost savings associated with the technique. Success for the project entails providing guidance in acquiring suitable data, demonstrating cost effectiveness, and achieving high-count accuracy with little variation in population estimates.


The demonstration and validation of thermal videography to monitor populations of bats and birds that use caves and other structures for colony roost sites will greatly improve monitoring efforts at areas where animals naturally congregate. The benefits yielded from this project will include: (1) detailed setup instructions that enable transferability to installation managers and (2) a methodology that provides higher quality animal census data by removing subjectivity from the process of estimating population trends. Improving the quality of population trends will assist in future conservation efforts, which serve to minimize potential impacts of TER-S on DoD installations. (Anticipated Project Completion - 2018)

  • Habitat,

  • Demonstration,

  • Monitoring,