The Japanese squirrel (''Sciurus lis'') is a

tree squirrel Tree squirrels are the members of the squirrel Family (biology), family (Sciuridae) commonly just referred to as "squirrels". They include more than 100 arboreal species native to all continents except Antarctica and Oceania. They do not form a ...

in the genus ''

Sciurus The genus ''Sciurus'' ( or ) contains most of the common, bushy-tailed squirrels in North America, Europe, Temperate zone, temperate Asia, Central America and South America. Species The number of species in the genus is subject to change. In 200 ...

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

. It was described by Dutch zoologist

Coenraad Jacob Temminck Coenraad Jacob Temminck (; 31 March 1778 – 30 January 1858) was a Dutch people, Dutch patrician, Zoology, zoologist and museum director. Biography Coenraad Jacob Temminck was born on 31 March 1778 in Amsterdam in the Dutch Republic. Fro ...

in 1844. The Japanese squirrel's native range includes large portions of the islands of

Honshū , historically known as , is the largest of the four main islands of Japan. It lies between the Pacific Ocean (east) and the Sea of Japan (west). It is the seventh-largest island in the world, and the second-most populous after the Indonesian ...

Shikoku is the smallest of the List of islands of Japan#Main islands, four main islands of Japan. It is long and between at its widest. It has a population of 3.8 million, the least populated of Japan's four main islands. It is south of Honshu ...

, and

Kyūshū is the third-largest island of Japan's four main islands and the most southerly of the four largest islands (i.e. excluding Okinawa and the other Ryukyu (''Nansei'') Islands). In the past, it has been known as , and . The historical regio ...

. The Japanese squirrel is absent from

Hokkaido is the list of islands of Japan by area, second-largest island of Japan and comprises the largest and northernmost prefectures of Japan, prefecture, making up its own list of regions of Japan, region. The Tsugaru Strait separates Hokkaidō fr ...

, where it is replaced by the related

red squirrel The red squirrel (''Sciurus vulgaris''), also called Eurasian red squirrel, is a species of tree squirrel in the genus ''Sciurus''. It is an arboreal and primarily herbivorous rodent and common throughout Eurasia. Taxonomy There have been ...

(''Sciurus vulgaris''), which is conversely absent from the rest of the Japanese archipelago outside Hokkaido. Recently, populations in south-western Honshū and Shikoku decreased, and those on Kyūshū disappeared. One of the factors affecting the recent local

extirpation Local extinction, also extirpation, is the termination of a species (or other taxon) in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with extinction, global extinctions. Local extinctions ...

s of this species seems to be forest fragmentation by humans. In certain areas, up to 35% of its diet can come from walnuts. It is possible the resulting dispersion has affected the evolution of larger seed sizes among Japanese walnut populations where Japanese squirrels are present. Furthermore, Japanese walnut ('' Juglans ailanthifolia'') is an important food for Japanese squirrels in lowland mixed-species forests in Japan. The Japanese squirrel's feeding technique consists of opening the hard shell of walnuts by chewing along the crease of the shell, embedding its teeth into the cleft, and airing out the two parts. This strategy seems to be efficient since it minimizes the time to finish eating an entire walnut. It has also been found that fallen dead trees serve as landmarks for the movement, vigilance, and resting of Japanese squirrels. Deadwood also can serve as hoarding sites for Japanese squirrels, which is crucial for their survival. The increase of deadwood may provide benefits to small mammals, such as the Japanese squirrel, and the quality of habitat is improved significantly.

References

External links

* Endemic mammals of Japan Sciurus Mammals described in 1844 Taxonomy articles created by Polbot Taxa named by Coenraad Jacob Temminck {{Squirrel-stub