The influence of audio-lures on capture patterns of migrant Northern Saw-Whet Owls

The effect of audio-lures on capture patterns of migrant Northern Saw-whet Owls (Aegolius acadicus) was assessed. The majority of new owls were captur ed within 12 m of the lure and capture frequencies decreased with increasin g distance away from the lure. Recaptures tended to occur farther away from the audio-lure than new captures. Capture locations of foreign retrapped o wls, however, were not significantly different than new owls. Although capt ure locations did not differ between adult and immature owls, there was a d etectable size bias in the distribution of capture locations. Smaller owls tended to be caught farther away from the lure than larger owls. Our result s demonstrate that when an audio-lure is used, a small number of mist nets is sufficient to capture substantial numbers of Northern Saw-whet Owls. How ever, studies targeting recaptures may benefit from the use of more nets sp aced over a larger area.