Lane, W.H. 1992. Distribution, status, and habitat requirements of the boreal owl (Aegolius funereus) in northeast Minnesota, 1990-1991. Final report submitted to the Nongame Wildlife Program, Minnesota Department of Natural Resources. 7+ pp.
Nocturnal, auditory surveys were conducted in 1990 and 1991 to locate singing male boreal owls (Aegolius funereus) in Lake and Cook Counties of northeast Minnesota. Nineteen male boreal owls were located in 1990 during 324.4 miles of surveys. Thirty male owls were located in 1991 during 720.2 miles of surveys. Six cavity trees were observed in 1990, and ten in 1991. Fourteen (88%) of the 16 cavities occurred in trembling aspen (Populus tremuloides). Three nest sites were documented in 1990, and 6 in 1991. Four male boreal owls were outfitted with backpack-type radio transmitters in both 1990 and 1991 to identify habitats used by the species during its circadian activities. Eighteen diurnal roost sites were observed and qualitatively described in 1990. Eighty-three diurnal roost sites were identified in 1991, and quantitative habitat measurements made. Seventy-two (87%) of the roost trees identified in 1991 occurred in lowland, black spruce (Picea mariana). In addition, 201 nocturnal relocations were recorded in 1991. This report summarizes results of boreal owl field studies conducted in 1990 and 1991.