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Wildlife of Metropolitan Akikawa Hills Natural Park

Olive-backed Pipit

The olive-backed pipit is in the order Passeriformes and the family Motacillidae. It is approximately 15 to 16 centimeters (5.9 to 6.2 inches) in length. In Japan, it is distributed from Hokkaido, Honshu, and through to Shikoku as a wandering or summer bird. It breeds in forests and meadows on the plains, and in forests and grasslands in the alpine belt, and moves to a warmer area in winter. Males and females are the same color: greenish brown from the forehead to the top of the body with vertical black streaks, whitish on the underside of the body, and yellowish brown on breast and flanks. It eats plant seeds, and waggles its tail feathers up and down while walking on the ground. While flying, it emits a call that sounds like “bing, bing, zizui, zizui”. This is the origin of its Japanese name, binzui.

Olive-backed pipit

Bull-headed Shrike

is approximately 20 centimeters (7.8 inches) in length. Habitats range from plains to agricultural land, forest greenery, and the banks of the rivers in the lower mountains across Japan. The body is small, but the beak is shaped like that of a hawk and is sharp. It has even been known to catch small birds. It has a habit, called “Shrike’s quick sacrifice,” of impaling prey on a thorn of a branch of a tree or wedging it in a notch between two branches.

Bull-headed shrike

Forest Green Tree Frog

The forest green tree frog is in the order Anura, the family Rhacophoridae, and the genus Rhacophorus. It is an endemic species of Japan and distributed throughout Honshu (the main island of Japan) and Sado Island. The male is approximately 42 to 62 millimeters (1.6 to 2.4 inches) in length, and the female is approximately 59 to 82 millimeters (2.3 to 3.2 inches) in length. The female is larger, and the male calls by expanding the air sac under the throat. It has round suckers on its toes and uses them to live in trees. It is rarely found on the ground. From April to July during the breeding season, it appears around ponds and swamps in woodland. In a tree standing at the edge of the water, it creates a nest of a ball of white foam (about 10 centimeters (3.9 inches) wide) and lays eggs in it. The tadpoles hatch in the nest and fall together with the foam when it collapses in the rain. The Tokyo Metropolitan Government has assigned this frog a Near Threatened (NT) status.

Forest green tree frog

Harvest Mouse

The harvest mouse is the smallest rodent in Japan being approximately 5 to 8 centimeters (2 to 3.1 inches). In Japanese, it is called as Kaya-nezumi, which means mouse of Japanese pampas grass, because it inhabits meadows, crop fields, and marshes where plants of the rice family such as Japanese pampas grass grow. Its staple foods are the seeds of the plants of the rice family, and insects such as grasshoppers and locusts. It skillfully weaves plant leaves to build a ball-shaped nest in the middle of the stalk, like a bird's nest, and rests there or nurtures its young. In winter, these frogs live in a tunnel dug underground. When they climbs up or down the stalk of Japanese pampas grass, they winds their long tails around the stems. During a nesting survey conducted by Akiruno City, nests were identified near the Akigawa River

Harvest mouse

Mountain Cherry and Yoshino Cherry Trees

In Akigawa Gorge, there is a fantastic view of cherry blossoms (known as Kosho cherry blossoms) along the Akigawa River and Yoshino, and the weeping cherry blossoms, are astonishing in the precincts of the Kotokuji Temple and around Owada on the way to the temple. In addition, the precincts of Kogon Temple, founded by Takauji Ashikaga in Akiruno City, contain a mountain cherry tree that is said to be 400 years old and is designated as one of the three giant trees of Tokyo. (The other two are a tree called Sakurakkabu on Oshima, and a tree called Ozakura on Miyakejima.) The Tokyo Metropolitan Government has designated these trees as natural monuments. The mountain cherry trees begin flowering at the end of March, and you can also view the magnificent cherry blossoms while walking in the park.

Yoshino cherry trees in Kosho

Dogtooth Violet

Dogtooth violet is a perennial belonging to the Erythronium genus of the Liliaceae family. It has a stem up to about 10 to 20 centimeters (3.9 to 7.9 inches) long. It produces red-purple flowers on a stalk that grows between two leaves, and the flowers bloom downwards. Before the trees in the forest open their leaves, the flowers open on sunny days as the earth warms. The flowers close night and in bad weather, but they sometimes open if the temperature is high. Flowering season is from April to June. Dogtooth violets grow in the mountain ranges; in some locations, they grow in groups.

Dogtooth violets

Forest Ghost Flower

The forest ghost flower is a parasitic plant belonging to the genus Aeginetia of the family Orobanchaceae. The leaves are egg-shaped, and the flowers bloom from July to August. The corolla is a cylindrical shape, becoming a lip shape. It grows wild from the temperate zone in Eastern and Southern Asia including Japan across the tropics. The flower mainly lives as a parasite on pampas grass, and also lives as a parasite on plants in the rice family, myoga, plantain lily, and yucca, etc. It grows up to 15 to 50 centimeters (5.9 to 7.9 inches) long. The Japanese name, nanban-giseru (literally “Portuguese pipe”), derives from the fact that the shape of the flower resembled the pipes that Spanish and Portuguese people held in their mouths.

Forest ghost flower

Japanese Helwingia

Japanese helwingia is a deciduous shrub belonging to the order Aquifoliales and known as Yome-no-Namida, which means “tears of a young bride”. It is native to forests in the mountains of Japan from Southern Hokkaido to Kyushu. It is an unusual plant with flowers blooming on the leaves and it grows up to 2 meters (6.6 feet) high. The stem is not so thick, and the leaves are similar to a raft. The flowers and fruits bloom on leaves resemble people on a raft, which is the origin of the Japanese name, Hanaikada (which means “flowers on a raft”).

Japanese helwingia

Golden-rayed Lily

The golden-rayed lily is a bulb plant of the genus Lilium of the family Liliaceae, which is native to Japan. It is distributed at forest edges and grasslands of mountains in the Kinki region and the northern area of Japan, excluding the Hokuriku region. The the Japanese name, Yamayuri, means “mountain lily”. It is also called Satoyama-no-Hoseki (which means a "jewel in a mountain close to a rural settlement") and is a plant representing the summer forest. Although the best time to see the flowers is from the middle to the end of July, the flowering season is different in that the early blooming flowers are just after Tanabata (the star festival on July 7) and the late blooming flowers appear at the beginning of August. However, you can definitely enjoy the beautiful golden-rayed lilies between middle and late July.

Golden-rayed lily

Pin Oak and Sawtooth Oak

Pin oaks and sawtooth oaks are tall deciduous trees in the family Fagaceae. Pin oaks grow to approximately 20 meters (65.6 feet) high. Sawtooth oaks grow to approximately 15 to 20 meters (49 to 66 feet) high. Both flower in April or May. Pin oak produces hanging flowers along with the spread of young leaves. In the autumn, it drops acorns. Small yellow male flowers hang down from sawtooth oaks in tufts of about 10 centimeters (4 inches). The female flowers are small and red and are almost not noticeable when they bloom at the base of the leaves. Sawtooth oaks also produce acorns. Pin oaks and sawtooth oaks are found in wooded areas in Japan, and there are many communities growing along the Akigawa River.

Pin oaks and sawtooth oaks


The hydrangea is a deciduous shrub of the genus hydrangea of family Hydrangeaceae. It flowers from the middle of June to early July. At Minamisawa Ajisai-mountain (Minamisawa Hydrangea Mountain), located in Akigawa Gorge, trees along the roads and the entire slopes of the mountain are covered with blue and pink colors when hydrangeas are in full bloom, and the appearance is truly impressive. Tranquil mountain villages look as if they are filled with decorations when the beautiful hydrangea flowers. A wide variety of hydrangeas, such as hydrangea and lacecap hydrangea, bloom in the same season in the Hydrangea Garden of Tokyo Summerland, which extends into the lush green Akikawa Hills.

Minamisawa Ajisai-mountain


このページの担当は自然環境部 緑環境課 自然公園計画担当です。

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