Identifying Individual Northern Spotted Owls by Voice at Point Reyes National Seashore

Rick reports data suggesting individual male Northern Spotted Owls (Strix occidentalis caurina) can be distinguished by characteristics of their Four Note Location Calls (FLC). He recorded owls while accompanying field biologists as they monitoried owls on historic breeding territories, including sites where previously banded owls were re-sighted during the study period (2006–2012). Using spectrograms, he estimated pitch contours, and measured frequency and timing of the calls. Discriminant Analysis matched calls to site with a mean success rate of 96% at four sites. One banded owl was re-sighted over a five year period, and its 17 FLC classify correctly. Graphical analysis and simulation runs suggest that individually identifiable calls may occur at five additional study sites with smaller sample sizes. Discussion topics include need for further study and potential usefulness of acoustic monitoring in situations where Barred Owls also occur since they display individual vocal identity as well.

Speaker: Rick Johnson, PRNS Volunteer