Swengel, Scott R., and Ann B. Swengel. 1987. “Study of a Northern Saw-whet Owl Population in Sauk County, Wisconsin.” In Biology and Conservation of Northern Forest Owls: Symposium Proceedings, February 3–7, Winnipeg, Manitoba, edited by Robert W. Nero, Richard J. Clark, Richard J. Knapton, and Robert H. Hamre, 199–208. General Technical Report RM-142. Fort Collins, CO: USDA Forest Service, Rocky Mountain Forest and Range Experiment Station.