The eruption of Mount Ontake in September killed dozens of hikers, but also probably decimated the population of a rare bird — the rock ptarmigan, a much-loved symbol of Japan's alpine region.

The bird, called the "raicho" (thunder bird) in Japanese, is considered quite tame and has striking plumage that changes with the seasons: mottled in summer and mostly white in winter. The bird is designated as a Special Natural Monument by the Cultural Affairs Agency, and the Environment Ministry's Regional Red List declares it an endangered species.

Experts believe the thick layer of ash left by the Sept. 27 eruption of the 3,067-meter volcano straddling Gifu and Nagano prefectures may have killed the plants the bird lives on and reshaped its habitat.