Marshall, 1945 Polar Otus podarginus the same pair will do this from the same tree each evening. The majority begin when it's getting dark & keep it up all night, tho calling less frequently after the first couple hours. Early calling: one pair at little N Koror ridge, 1 pr. at Pelelin. Voice: Call about every 15 min. (1st part of four hours of evening). It seems to be part of a very set series of doings & if series is interrupted, bird will wait another 10-15 min & start over again, as the following exceptional case shows: Heard the ♂ of a pair based on ridge calling from tree edge lagoon. I didn't climb in & call was short. Figured he would stay there - ran 250 yds to tree I figured he would occupy. In 10 min he gave a few muffled notes - silent again 15 min, then began regular series - I crashed up towards him & he stopped in middle of series. I therefore would still remain] I shot at a movement in the leaves (couldn't shic him) & scared him away. This is due to interruptions) in contrast to the established mode of conduct: Call is series of notes lasting 2-3 minutes, consisting of rise to climax in 1½-2½ min, definite climax for ½ min, tho another tapering off for 15-25 sec.