DISTRIBUTION AND HABITAT ASSOCIATIONS OF NORTHERN PYGMY-OWLS IN OREGON

ABSTRACT We conducted acoustic lure surveys of Northern Pygmy-Owls (Glaucidium gnoma) on 224 transects that were systematically placed in forested areas in Oregon. Our objectives were to determine if pygmy-owls were associated with particular forest types, regions, or with large trees. We also examined temporal variation in numbers of owls located. We detected pygmy-owls at 161 of 224 transects. The mean number of owls detected per linear km on individual transects was 0.21 (SE  =  0.01, range of means  =  0–1.07, N  =  224). Mean detections per transect were highest in the Western Cascades, intermediate in the Coast Ranges, Klamath Mountains, Eastern Cascades, and Blue Mountains, and lowest in the Willamette Valley and High Desert Ecoregions. The mean number of owls detected per transect was highest in mesic Douglas-fir (Pseudotsuga menziesii) and ponderosa pine forests (Pinus ponderosa), intermediate in conifer/hardwood and mixed-conifer forests, and lowest in alpine conifers, deciduous hardwoods, and w...