Autumn populations and movements of migrant Northern Saw-whet Owls (Aegolius acadicus) at Little Suamico, Wisconsin

Abstract

Northern Saw-whet Owls (Aegolius acadicus) were once considered a "rare" bird in Wisconsin. In the 1960's mist netting at bird-banding stations revealed Saw-whets to be a regular, uncommon migrant. Passive mist netting was initiated at the Little Suamico Ornithological Station in 1971. Our Saw-whet Owl experiences were similar to other banding stations until 1986, when we developed an "audiolure". This technique, utilizing an amplified Saw-whet "solicitation" courtship call increased our annual catch more than tenfold. Now in use at major banding stations in the western Great Lakes area, this technique has resulted in over 2,000 Saw-whets being netted each autumn. Currently at Little Suamico 5 percent of adult owls netted have been previously banded. Approximately 40 percent of owls netted are northbound. Direct interstation recoveries reveal that Saw-whets migrate slowly at our latitude and often not in the expected southbound direction. Adults move greater distances per night than immatures. More than 200 recoveries and recaptures in subsequent years have been generated at Little Suamico since 1986. Migration dates and nightly travel distances suggest that many of the Saw-whet Owls that we encounter spend the winter in Wisconsin.

Parent Publication

• Biology and conservation of owls of the Northern Hemisphere: 2nd International symposium

Citation

Erdman, Tom C.; Meyer, Tom O.; Smith, Jerry H.; Erdman, Debra M. 1997. Autumn populations and movements of migrant Northern Saw-whet Owls (Aegolius acadicus) at Little Suamico, Wisconsin. In: Duncan, James R.; Johnson, David H.; Nicholls, Thomas H., eds. Biology and conservation of owls of the Northern Hemisphere: 2nd International symposium. Gen. Tech. Rep. NC-190. St. Paul, MN: U.S. Dept. of Agriculture, Forest Service, North Central Forest Experiment Station. 167-172.