Shokanbetsu-Teuri-Yagishiri

Shokanbetsu-Teuri-Yagishiri Quasi-National Park is situated on the Sea of Japan coast of northwestern Hokkaido, encompassing the Shokanbetsu-dake mountain range on the mainland coast along with two remote offshore islands, Teuri-to and Yagishiri-to. The park protects a diverse range of natural environments from rugged coastal cliffs and forested mountain terrain on the mainland to the windswept island ecosystems of Teuri and Yagishiri, which support some of the most spectacular seabird colonies in Japan. Mount Shokanbetsu (1,492 meters) is the highest peak in the Mashike Mountains and offers exceptional alpine scenery accessible from Hokkaido's northwest coast. The quasi-national park designation reflects the high ecological and scenic value of this landscape, which combines maritime, island, and mountain environments within a single protected area framework.

The wildlife of Shokanbetsu-Teuri-Yagishiri is defined by the extraordinary seabird colonies on Teuri Island, which hosts one of Japan's most important breeding aggregations of rhinoceros auklets (uma-suzume), with hundreds of thousands of pairs nesting in burrows across the island plateau during summer. Spectacled guillemots, black-tailed gulls, and tufted puffins are among the other seabird species breeding on Teuri and Yagishiri. Steller sea lions and harbor seals haul out on rocky shores around both islands. On the mainland Shokanbetsu mountains, Ezo brown bear (Hokkaido brown bear), Hokkaido sika deer, and red fox are the dominant large mammals. The mountain forests harbor Blakiston's fish owl, the world's largest owl and one of Japan's most endangered bird species, which requires large old-growth riparian trees adjacent to fish-bearing streams. Hokkaido squirrel, Siberian chipmunk, and alpine ptarmigan are among the characteristic highland species.

Vegetation in Shokanbetsu-Teuri-Yagishiri spans a remarkable range from the island grasslands and coastal shrublands of Teuri and Yagishiri to the full altitudinal sequence of Hokkaido mountain vegetation on Mount Shokanbetsu. The islands support wind-sculpted low shrub communities and maritime grassland dominated by Japanese pampas grass, with spring wildflowers including lilies and irises that bloom abundantly across the island terrain. The mainland mountain forest transitions from mixed conifer-broadleaf forest in the lower zones, dominated by Sakhalin fir (Todo-matsu) and Hokkaido spruce (Ezo-matsu), through Japanese beech forest in the middle elevations, to dwarf stone pine (haimatsu) krummholz and alpine tundra communities near the summit. The summit ridge supports a diverse alpine flora with characteristic Hokkaido alpine species including alpine buttercups, anemones, and specialized sedge meadows in snowmelt depressions.

Mount Shokanbetsu and the Mashike Mountains are composed primarily of volcanic and sedimentary rocks formed through the complex tectonic history of Hokkaido, including arc volcanism and accretion of oceanic terranes. The rugged coastal cliffs visible along the Sea of Japan shore result from the active erosional processes driven by Japan Sea wave action against the relatively soft rock formations. Teuri and Yagishiri islands are believed to be remnants of elevated seafloor terrain that became isolated as sea levels changed at the end of the last glacial period, when rising seas flooded the lowlands connecting them to the mainland. The islands' flat-topped topography and surrounding sea cliffs reflect a history of wave planation during periods of different sea level. The Sea of Japan coastline of northwestern Hokkaido is geologically dynamic, with ongoing coastal erosion reshaping the cliffs and rocky shores.

Northwestern Hokkaido experiences one of Japan's most severe climates, with intense winter cold, heavy snowfall, and the presence of drift ice (ryuhyo) from the Sea of Okhotsk that pushes into the Japan Sea along Hokkaido's northwestern coast. The Shokanbetsu mountains intercept moisture-laden winds off the Japan Sea, generating exceptionally heavy snowfall that can accumulate to several meters on the upper slopes. Winter temperatures in the mountain interior can drop to minus 20 degrees Celsius or below. The offshore islands experience somewhat moderated temperatures due to their marine exposure but are subject to powerful winter storms and persistent sea fog in summer. Summer on Teuri and Yagishiri is remarkably cool compared to mainland Hokkaido, making the islands a summer birding destination. The park is most accessible from May through October, when mountain snow has sufficiently melted for hiking.

Teuri and Yagishiri islands have been inhabited for thousands of years, with evidence of Jomon period settlement indicating that fishing communities established themselves on these offshore islands many millennia ago. The islands later became home to Ainu communities who maintained fishing and hunting traditions adapted to the marine environment, and traces of this Indigenous heritage remain in place names and oral traditions of the region. Japanese fishing communities settled on the islands during the Edo and Meiji periods, developing substantial herring (nishin) fisheries that made Hokkaido's northwestern coast economically significant in the late nineteenth and early twentieth centuries. The herring boom and subsequent bust fundamentally shaped settlement patterns throughout the region. The mainland Shokanbetsu area was settled later as Hokkaido's interior was opened for agriculture and forestry in the Meiji era, with fishing communities establishing bases along the coastal margins.

Shokanbetsu-Teuri-Yagishiri was designated as a Quasi-National Park by Japan's Ministry of the Environment to protect the exceptional combination of coastal mountain scenery, island ecosystems, and seabird breeding colonies that together constitute one of Hokkaido's most ecologically significant protected landscapes. The inclusion of Teuri Island in the park was driven specifically by the island's extraordinary seabird values, as its rhinoceros auklet colony represents one of the largest aggregations of this species in the world and is of international conservation significance. The quasi-national park designation represents a higher level of protection than prefectural natural park status, reflecting the national and international importance of the park's natural values. Management of the island ecosystems is a particular challenge given their remoteness and sensitivity to visitor disturbance during seabird breeding season.

The ascent of Mount Shokanbetsu from the Mashike side is the primary hiking attraction on the mainland, with well-maintained trails passing through old-growth forest before ascending to the alpine zone and summit ridge, where panoramic views extend across the Sea of Japan and the surrounding Mashike Mountains. Summer wildflower displays on the alpine slopes are a notable attraction. Teuri Island is the principal destination for wildlife and birdwatching visitors, offering evening viewing of tens of thousands of rhinoceros auklets returning to their burrows from the sea at sunset — one of Japan's most dramatic wildlife spectacles. Whale watching tours operate from Teuri Island during summer, as humpback and minke whales frequent the productive waters of this coast. Yagishiri Island offers a quieter island experience with cycling trails around the island's coastal perimeter and rich spring wildflower meadows.

Access to Teuri and Yagishiri islands is by ferry from Haboro port on the Hokkaido mainland, with services operating from May through November. Teuri Island has a small guesthouse and minshuku accommodation, and advance booking is essential during peak summer season when birdwatching visitors fill the limited lodging. Yagishiri Island similarly has a small number of accommodation options and is quieter. Mount Shokanbetsu is reached by road from the town of Mashike on the Sea of Japan coast, then by driving or hiking to trailheads in the Shokanbetsu-dake Natural Recreation Forest. Mashike town provides accommodation, restaurants, and transport connections. The JR Haboro Line previously connected this coast but was discontinued, so access by public transportation is now limited; most visitors arrive by private vehicle or rental car from Asahikawa or Sapporo.

Conservation at Shokanbetsu-Teuri-Yagishiri focuses primarily on protecting the island seabird colonies, which are vulnerable to human disturbance during the breeding season, introduction of invasive predators, and changes in marine prey availability driven by climate change and fishing pressure. Teuri Island's rhinoceros auklet colony has been subject to long-term monitoring and represents a globally important dataset for seabird population trends in the northwestern Pacific. Management of visitor access during breeding season, including trail restrictions and lighting controls that could disorient returning birds at night, is carefully regulated. On the mainland, old-growth forest conservation is prioritized to protect Blakiston's fish owl and other old-growth dependent species. Hokkaido brown bear management is an ongoing challenge as bear-human interactions increase near the park margins. Marine protected area coordination is needed to address the fisheries management context within which the island ecosystems exist.