Aerial ungulate surveys with a combination of infrared and high–resolution natural colour images

Information on animal population sizes is crucial for wildlife management. In aerial surveys, we used a silent light aircraft (microlight) and a combination of a computer–linked thermal infrared camera (640 x 480 pixels) to detect ungulates and high–resolution visual images (5,616 x 3,744 pixels) to identify specific species. From winter 2008/2009 to winter 2010/2011, we flew 48 missions over three German national parks and a German/ French biosphere reserve. Within each study area, we followed non–overlapping linear transects with a flying altitude ~450 m above ground level and scanned 1,500–2,000 ha every two hours of flight time. Animals best detected and identified were red deer and fallow deer. Detection rates with respect to the type and density of vegetation cover ranged from 0% (young spruce) to 75% (young defoliated beech) to 100% (open land). This non–invasive method is cost–effective and suitable for many landscapes.