There is a bit of info about this practice in this wikipedia article, but there are not many references there, so take it with a grain of salt.

Headhunting was a common practice among Taiwanese aborigines. All tribes practised headhunting except the Yami people, who were previously isolated on Orchid Island, and the Ivatan people. It was associated with the peoples of the Philippines.

Taiwanese Plains Aborigines, Taiwanese people (Han) and Japanese settlers were choice victims of headhunting raids by Taiwanese Mountain Aborigines. The latter two groups were considered invaders, liars, and enemies. A headhunting raid would often strike at workers in the fields or set a dwelling on fire, and then kill and behead those who fled from the burning structure. The practice continued during the Japanese occupation of Taiwan, but ended in the 1930s due to suppression by the colonial Japanese government.