Urban Safari: Tokyo wildlife in the Kanda River

For most, the idea of 'Tokyo wildlife' summons images of urban pests like crows, rats and stray cats. What self-respecting animal would dare live in this jungle of metal, concrete and glass?

Intrepid naturalists, of course, know better. Clinging to the nooks and crannies of Tokyo's urban sprawl is a surprising amount of wildlife. Among the most fertile grounds for wild species, Kandagawa, or the Kanda River, snakes for roughly 15 miles through suburban and central Tokyo. From its headwaters in Kichjijoji's Inokashira Park, the river winds through urban Nakano and Shinjuku all the way east to the Sumida River, filling the moat around the Imperial Palace along the way.

Like many Japanese rivers, the entirety of the Kanda has been sheathed in concrete. During Japan's rapid economic growth in the 1970s and '80s, suburban waste water poured into the Kanda at such a clip that it earned the nickname 'River of Death.'

A reworking of the sewer network in the 1990s, however, dramatically improved the quality of the water, allowing formerly displaced animals to return. In celebration of the river's revival as a spot to spot Tokyo animals, here's a list of creatures found along the first several kilometers of the Kanda River.

Soft-shelled turtle

'Suppon' to the Japanese, these large, floppy counterparts to hard-shelled turtles are a common sight in the Kanda. They're easiest to spot in shallower sections of the river, particularly on clear days when they sun near the surface. Considered a delicacy in Japan and China, soft-shelled turtle meat is often prepared in a soup.

Japanese pond turtle

Once a common Kanda River animal, Japanese pond turtles have largely been displaced from their original habitat by an invasive foreign species, the North American red-eared slider.

Red-eared slider

Originally released into Inokashira Pond by people who no longer wanted to care for them as pets, the red-eared slider turtle has singlehandedly displaced some 90 percent of the pond turtle population.

Japanese rat snake

Known as 'ao-daisho,' or 'green general,' this common snake can reach lengths of up to two meters, though one-meter specimens are more common. Although non-venomous, they occasionally bite if disturbed. Happy on land and in water, they are often spotted swimming through reeds in the river.

Tanuki

The elusive 'tanuki,' or Japanese raccoon-dog, was revered as a trickster in local folklore. Largely displaced by the spread of residential development, a few stragglers sometimes make their way in the suburbs. A tanuki skeleton was discovered in nearby Inokashira Park in early 2009, indicating the animal's presence in the area. Largely nocturnal, they are extremely difficult to spot.

Night heron

Often spotted sleeping in branches during the day, these nocturnal predators hit the water at dusk in search of fish and small crustaceans. Night herons are occasionally seen near manmade ponds, gazing longingly at carp far too large to fit in their beaks.

Mandarin duck

A close relative of the North American wood duck, these brightly plumed birds are common in Inokashira Pond and along the Kanda River.

White heron

These large, majestic birds are often spotted wading through the shallows, poking their beaks into the water in search of small fish and crustaceans, particularly juvenile crayfish.

Koi

A staple of ponds the world over, huge numbers of these ornamental carp dwell in the Kanda. After generations of unsupervised breeding, however, most koi have returned to their natural drab gray coloration. That said, rarer calico carp do appear in the wild.

Hiroko Yoda and Matt Alt run AltJapan Co., Ltd., a Tokyo-based  company that specializes in translating video games and other pop culture. They are the co-authors of "Yokai Attack! The Japanese Monster Survival Guide," "Ninja Attack! True Tales of Assassins, Samurai, and Outlaws," and "Yurei Attack! The Japanese Ghost Survival Guide."

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