Duncan, James R. and Patricia A. Duncan. (1998) Northern Hawk-Owl (Surnia ulula), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: doi:10.2173/bna.356.
Duncan, James R. and Patricia A. Duncan. (1998) Northern Hawk-Owl (Surnia ulula), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: doi:10.2173/bna.356.
Sonerud, Geir A. (1992). "Search tactics of a pause-travel predator: adaptive adjustments of perching times and move distances by hawk owls (Surnia ulula)". Behav Ecol Sociobiol. 30 (3–4): 207–217. Bibcode:1992BEcoS..30..207S. doi:10.1007/BF00166705. S2CID24152225.
Rohner C, Smith JN, Stroman J, Joyce M, Doyle FI, Boonstra R (1995). "Northern Hawk-Owls in the nearctic boreal forest: Prey selection and population consequences of multiple prey cycles". Condor. 97 (1): 208–220. doi:10.2307/1368997. JSTOR1368997.
Cheveau M, Drapeau P, Imbeau L, Bergeron Y (2004). "Owl winter irruptions as an indicator of small mammal population cycles in the boreal forest of eastern North America". Oikos. 107 (1): 190–198. Bibcode:2004Oikos.107..190C. doi:10.1111/j.0030-1299.2004.13285.x.
Sonerud, Geir A. (1992). "Search tactics of a pause-travel predator: adaptive adjustments of perching times and move distances by hawk owls (Surnia ulula)". Behav Ecol Sociobiol. 30 (3–4): 207–217. Bibcode:1992BEcoS..30..207S. doi:10.1007/BF00166705. S2CID24152225.
Cheveau M, Drapeau P, Imbeau L, Bergeron Y (2004). "Owl winter irruptions as an indicator of small mammal population cycles in the boreal forest of eastern North America". Oikos. 107 (1): 190–198. Bibcode:2004Oikos.107..190C. doi:10.1111/j.0030-1299.2004.13285.x.
Rohner C, Smith JN, Stroman J, Joyce M, Doyle FI, Boonstra R (1995). "Northern Hawk-Owls in the nearctic boreal forest: Prey selection and population consequences of multiple prey cycles". Condor. 97 (1): 208–220. doi:10.2307/1368997. JSTOR1368997.
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Sonerud, Geir A. (1992). "Search tactics of a pause-travel predator: adaptive adjustments of perching times and move distances by hawk owls (Surnia ulula)". Behav Ecol Sociobiol. 30 (3–4): 207–217. Bibcode:1992BEcoS..30..207S. doi:10.1007/BF00166705. S2CID24152225.
Gill, Frank; Donsker, David; Rasmussen, Pamela, eds. (January 2021). "Owls". IOC World Bird List Version 11.1. International Ornithologists' Union. Retrieved 22 May 2021.