At a zoo northeast of Tokyo, two female Hokkaido brown bears were in an unusually lively mood earlier this year thanks to a change in diet — they were being fed the carcass of a wild boar.

In their natural environment, Ai and Eriko would have spent most of their time hunting for food, walking many hours for prey, according to keeper Yuya Yamashita, 29, at the Kamine Zoo in Hitachi, Ibaraki Prefecture. Feeding them a carcass, fur still attached, was meant to stimulate those hunting instincts.

The initiative is part of a "carcass feeding" movement under way across Japan, inspired partly by the accumulation of corpses of wild animals hunted to prevent crop destruction. Support groups and wild-game businesses are jumping on the bandwagon.