Use of Modern Infrared Thermography Population Surveys for Wildlife DALE L. GARNER* Faculty of Environmental and Forest Biology College of Environmental Science and Forestry State University of New York Syracuse, New York 13210, USA H. BRIAN UNDERWOOD Cooperative Research Unit, National Biological Survey College of Environmental Science and Forestry State University of New York Syracuse, New York 13210, USA WILLIAM F. PORTER Faculty of Environmental and Forest Biology College of Environmental Science and Forestry State University of New York Syracuse, New York 13210, USA ABSTRACT / A commercially available thermal-infrared scanning system was used to survey populations of several wildlife species. The system's ability to detect species of different sizes in varying habitats relative to conventional survey methods, to differentiate between species in the same habitat, and the influence of environmental factors on operational aspects of employing this technology in the field were evaluated. Total costs for the surveys were approximately $0.36/ha. There were marked discrepancies in the counts of untrained observers and those from trained analysts. Computer-assisted analysis of infrared imagery recorded 52% fewer deer than were estimated from drive counts, and densities of moose were five times those estimated from conventional aerial methods. By flying concentric circles and using telephoto, detailed counts of turkeys and deer were possible. With the aid of computer-assisted analysis, infrared thermography may become a useful wildlife population survey tool. More research is needed to verify the actual efficiency of detection by combining aerial scans with ground truthing for a variety of species and habitats. With the mounting concern for more active man- agement of wildlife in urban areas and parks, there is a need to obtain accurate information on wildlife pop- ulations. Aerial surveys for population census or esti- mation of wild animals are fraught with difticulty (LeResche and Rausch 1974). However, many innova- tive technological and procedural developments have been employed in wildlife surveys to circumvent some of the more common problems (Davis and Winstead 1980). Recently, modern thermal-infrared (IR) scan- ning equipment has regained the widespread atten- tion of wildlife managers and trial use of the new technology is underway. We had the opportunity to test a state-of-the-art thermal-IR scanner and the computer software used in image analysis. While our opportunity did not allow for rigorously controlled experimental design, the trials did provide insight about the strengths and weaknesses of this approach to wildlife survey methods. KEY WORDS: Infrared; Wildlife;Population;Surveys *Author to whom correspondence should be addressed. Our paper describes the recent advances of the hardware and software technology and reports the results of our experience. Specific objectives were to investigate: (1) the ability of IR to detect animals of different sizes in varying habitats relative to conven- tional survey methods, (2) the ability of relatively un- trained observers to detect target animals in compari- son to computer-assisted analysis, (3) the influence of vegetation and weather conditions on detection, and (4) the relative costs of using infrared technology in the field. A thermal-IR system uses a detector, a thermal imager, and a real-time image recording device. The detector is responsible for converting radiant energy to an electrical signal, which, after processing, be- comes a visible image. Croon and others (1968), Mc- Cullough and others (1969), Addison (1972), Graves and others (1972), and Parker (19~'2) were among the first to demonstrate the operational uses of ther- mal-IR (i.e., emitted radiation in the far-lR spectral bands of 3-14 i~m) detectors for censusing large mammals. Parker (1972) concluded that sensors capa- ble of differentiating objects of small thermal contrast (i.e., < I~ at relatively low temperatures (- 23~ to Environmental Management Vol. 19, No. 2, pp. 233-238 @ 1995 Springer-VerlagNew York Inc.