Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.
The eastern North Pacific stock migrates northward to summer range in February-May, led by newly pregnant females. The southward migration (November-January), led by pregnant females, passes through Unimak Pass, Alaska, and for most individuals ends in the Mexican winter range. The southward migration is more concentrated and closer to shore than is the northward migration. Roundtrip migration is up to about 18,000 kilometers. Small numbers spend the summer along the west coast of North America, from California north (Rice, in Wilson and Ruff 1999).
The western Pacific stock migrates south from western and northern Sea of Okhotsk to the southern coast of China (Rice, in Wilson and Ruff 1999).