Kushiro-shitsugen National Park (釧路湿原国立公園), at 269 sq km, is Japan's largest undeveloped wetland. It was designated a national park in 1987 to combat urban sprawl and protect the habitat of numerous species, chiefly the tanchō-zuru (red-crowned white crane), the traditional symbol of both longevity and Japan.
In the early 20th century, the cranes were thought to be extinct due to overhunting and habitat destruction. In 1926, however, some 20 birds were discovered in the marshes here; with concentrated conservation efforts, they now number over 1000. Cranes can be seen year-round, but the best time to spot them is during winter when they gather at feeding spots.