INVASIVE OWLS

“sparred owl”

ResultsThere are clear differences between the

“traditional” contact calls of allopatric barred owls and the calls of barred owls that are sympatric with spotted owls.

Hypothesis: In areas of overlapping range, differences in contact calls will reinforce species isolation. Allopatric barred owls will show changes in the contact call to differentiate more clearly from the contact call of the spotted owl.

Methods Using sonograms from the Macaulay

Library and GIS mapping, we identified sympatric and allopatric samples of barred owl contact calls as well as spotted owls. Representative calls from each group were analyzed [number of syllables, max and min frequency, and frequency range of call, presence or absence of a descending trill on final syllable]

Reinforcement of species isolation in invasive barred owls

Spotted owl Strix occidentalis Barred owl Strix varia

Hypothesis: In areas of overlapping range, differences in contact calls will reinforce species isolation. Allopatric barred owls will show changes in the contact call to differentiate more clearly from the contact call of the spotted owl.

Using sonograms from the Macaulay Library and GIS mapping, we identified sympatric and allopatric samples of barred owl contact calls as well as spotted owls. Representative calls from each group were analyzed [number of syllables, max and min frequency, and frequency range of call, presence or absence of a descending trill on final syllable]

David Glick, Stacey Kiser, Linda Vick