Case report: long-distance overwater migration of the Northern Boobook, Ninox japonica, revealed by year-round GPS tracking

Relative to extensive research on soaring raptors, the propensity for overwater movement of owls is poorly known. To provide insights into the migratory routes of an owl species, Northern Boobooks Ninox japonica, breeding in East Asia, we attached GPS loggers to male Northern Boobooks in the Tohoku region of Japan.

A GPS logger successfully recorded the full annual cycle of one male, showing an example of a clockwise loop migration between Japan and Southeast Asia. The migration route via Luzon, Philippines, was consistent with previous band-recovery data. In both autumn and spring, the tracked owl undertook ocean crossings exceeding 1400 km. In wintering ground, the owl used a four-year-old secondary forest surrounded by oil palm plantations in Kalimantan, Indonesia.

This tracking record provides the first detailed description of the migration route of owls along the East Asian flyway and an initial insight into the migration and wintering ecology of the Northern Boobook. Our GPS tracking data, while not a statistically sufficient sample size, suggest that this species performs long-distance overwater migration.