Japan, an island nation, encompasses diverse climates from subarctic north to subtropical south. Its geography, with mountains, coastlines, and islands, fosters varied ecosystems. This environment supports a wide array of animal life, including many endemic species.
Unique Endemic Mammals
Japan’s isolation has led to the evolution of several distinct mammal species.
The Japanese Macaque (Macaca fuscata), often called “snow monkeys,” inhabits Honshu, Shikoku, and Kyushu, adapting to environments with months of snow. Their thick fur allows them to withstand cold temperatures, and they use volcanic hot springs for warmth. Females typically spend more time in trees, while males are more ground-dwelling.
The Tanuki (Nyctereutes viverrinus), or Japanese raccoon dog, is a canid native to Japan, found across Honshu, Kyushu, Shikoku, and Hokkaido. Despite its name, it is a member of the dog family, not closely related to raccoons. Tanukis are nocturnal and omnivorous, consuming fruits, insects, and small animals. They enter a shallow hibernation during winter, often in pairs.
The Japanese Serow (Capricornis crispus), a goat-antelope, lives in the mountainous forests of Honshu, Shikoku, and Kyushu. These agile ungulates navigate steep slopes and dense vegetation in temperate deciduous or coniferous forests. They are mostly solitary, marking territories with secretions from glands near their eyes. Serows primarily browse on leaves, shoots, and acorns.
Sika Deer (Cervus nippon) are widely distributed across Japan, inhabiting various forest types from subarctic to subtropical regions. These adaptable deer influence their ecosystems through grazing.
Diverse Avian Species
Japan’s location along major migratory flyways makes it a significant destination for numerous bird species.
The Red-crowned Crane (Grus japonensis) has a resident population in Hokkaido. Other populations migrate from breeding grounds in Siberia and Northeast China to winter in Korea and China. These large cranes prefer wetlands and rivers for nesting and foraging, feeding on water plants, seeds, fish, and insects.
The Japanese White-eye (Zosterops japonicus), also known as mejiro, is a small, common bird native to Japan and East Asia. It is recognized by its white eye-ring and olive-green plumage. These omnivorous birds forage for insects and nectar, pollinating flowers, especially camellias. Japanese White-eyes are found in various habitats, including woodlands, gardens, and coastal areas.
Japan’s islands serve as important stopover points for migratory birds along the East Asian-Australasian Flyway. Its varied landscapes provide essential breeding, feeding, and resting grounds for both resident and migratory populations, including various raptors and seabirds.
Rich Marine and Aquatic Life
Surrounded by the Pacific Ocean, Japan’s marine environment is rich in biodiversity, influenced by the convergence of major ocean currents. The warm Kuroshio Current flows northward from the Philippines, bringing warm, nutrient-poor waters and supporting diverse tropical species and coral reefs. Conversely, the cold Oyashio Current flows southward from the Arctic, carrying nutrient-rich waters. The collision of these two currents off Japan’s eastern coast creates a highly productive zone, fostering abundant marine life.
This convergence zone is a significant fishing ground, attracting various fish species like sardines, mackerel, anchovies, tuna, and salmon. Japan’s waters are also home to a variety of marine mammals, including numerous dolphin species. Larger marine mammals, including humpback and sperm whales, also traverse these waters, drawn by rich food sources. The diverse aquatic environments, from coral reefs in the south to cold-water ecosystems in the north, support a wide array of invertebrates and other aquatic creatures.
Reptiles, Amphibians, and Insects
Japan’s terrestrial and freshwater environments support a variety of reptiles, amphibians, and insects.
Among the notable reptiles is the Habu snake (Protobothrops flavoviridis), a venomous pit viper primarily found on the Ryukyu Islands, including Okinawa. These nocturnal snakes are typically terrestrial, often found in coastal habitats, forests, and cultivated fields. Habu snakes are characterized by their large heads and olive-green or brown blotched patterns.
Amphibian diversity includes the Japanese Giant Salamander (Andrias japonicus), the second-largest salamander species globally. Endemic to Japan, these amphibians inhabit cold, fast-flowing mountain streams and rivers. They are nocturnal and feed on freshwater crabs, fish, and insects.
Japan’s insect population is vast and includes several species. The Japanese rhinoceros beetle (Trypoxylus dichotomus) is a large, dark brown beetle, with males distinguished by a prominent Y-shaped horn used in contests over territory and mates. These nocturnal beetles emerge in summer and feed on tree sap and fruit.
Cicadas, known as “semi” in Japanese, are a symbol of summer. Around 30 different species of cicadas are found across Japan, each with distinct calls, such as the “higurashi” (evening cicada) and “abura-zemi” (oil cicada). These insects spend years underground as nymphs before emerging for a short adult life.