LIMITATIONS OF FAR-INFRARED THERMAL IMAGING IN LOCATING BIRDS

The utility of far infrared (FIR) thermal imaging devices to detect an d census birds in the field was examined. A Thermovision 210 was used to survey individuals and/or nests of Great-horned Owls (Bubo virginia nus), Pileated Woodpeckers (Dryocopus pileatus), Northern Flickers (Co laples auratus), Barrow's Goldeneyes (Bucephala islandica), Buffle-hea ds (Bucephala albeola), Malards (Anas platyrhynchos), Green-winged Tea l (Anas crecca), Lapland Longspurs (Calcarius lapponicus) and Pectoral Sandpipers (Erolia melanotos). Thermal imaging was successful in dete rmining activity at nests of all four cavity-nesting species and in fi nding nests of Arctic tundra birds if their approximate location was k nown. FIR thermal imaging was not useful, however, in detecting the ac tive, open nests of Mallards or Green-winged Teal, nor was it useful i n locating resting waterfowl or Great-horned Owls. It was successful a t locating Arctic tundra birds. These differences are largely attribut able to variation among species in the insulative property of nests or feathers. It is concluded that FIR imaging will be of limited utility in censusing most avian populations, although it may provide a useful , abeit expensive tool, to assess nest occupancy of cavity- or burrow- nesting birds, or to determine the activity of birds in open habitats.