The Forest in Summer
Summer is breeding season for many animals in Nasu Heisei-no-mori Forest. When not seeking a mate, black bears occupy themselves by feeding on ants, bee larvae, wild cherries, and herbs. It is also mating time for the forest birds, and the treetops echo with the calls of Japanese thrushes, Japanese grosbeaks, ashy minivets, and other birds establishing their nests. Tiny dormice spend the daylight hours curled up in holes in trees, but at night they become active, eating insect larvae, nuts, and their favorite treat: nectar from the many flowers in bloom.
From early July through August, the forest echoes with the shrill buzzing of ezozemi, a large cicada with a striking gold-and-black pattern on its back. Huge golden-ringed dragonflies—82 to 114 millimeters long, the largest type native to East Asia—flit through the forest between August and early September.
Several unusual flowers bloom during the summer months. The frail and fascinating ginryōsō (Monotropastrum humile) is found in forests with little human interaction. Blossoming between late May and late June, this ghostly white plant lacks chlorophyll, and instead gains its nutrients from symbiotic fungi. From June through July, the toxic kobaikeisō (Veratrum stamineum) produces white flowers that cause cramps and vomiting when eaten by humans. The ezoajisai, a variety of mountain hydrangea found only in Japan, blooms in mid-July, and the purple flowers of deathly toxic monkshood (torikabuto) bloom in August and September.
The forest is home to the Japanese fire belly newt, Japanese skink, and Japanese grass lizard, all of which are endemic species, found only in Japan. The Montane brown frog and Tago’s brown frog, also endemic, are common in Nasu. These amphibians frequently fall prey to a venomous—but very shy—serpent known as the tiger keelback.