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'' contains most of the common, bushy-tailed squirrels in North America, Europe, temperate Asia, Central America and South America. Species The number of species in the genus is subject to change. In 2005, Thorington & Hoffma ...

endemic Endemism is the state of a species being found 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 found elsew ...

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

. It was described by Dutch zoologist

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

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

Honshū , historically called , is the largest and most populous island of Japan. It is located south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Straits. The island separa ...

Shikoku is the smallest of the four main islands of Japan. It is long and between wide. It has a population of 3.8 million (, 3.1%). It is south of Honshu and northeast of Kyushu. Shikoku's ancient names include ''Iyo-no-futana-shima'' (), '' ...

, and

Kyūshū is the third-largest island of Japan's five main islands and the most southerly of the four largest islands ( i.e. excluding Okinawa). In the past, it has been known as , and . The historical regional name referred to Kyushu and its surround ...

. Recently, populations on south-western Honshū and Shikoku decreased, and those on Kyūshū disappeared. One of the factors affecting the local

extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

of this species seems to be

forest fragmentation Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological processes ...

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 ''Juglans ailantifolia'' (synonyms ''J. cordiformis'' and ''J. sieboldiana'' and '' J. mandshurica'' var. ''sachalinensis''), the Japanese walnut ( ja, 鬼胡桃 ''oni-gurumi''), is a species of walnut native to Japan and Sakhalin. It is a deci ...

populations where Japanese squirrels are present.Tamura, Noriko. “Population Differences and Learning Effects in Walnut Feeding Technique by the Japanese Squirrel.” ''Journal of Ethology'' 29.2 (2011): 351–363. Web.Tamura, N. and Hayashi, F. (2008), Geographic variation in walnut seed size correlates with hoarding behaviour of two rodent species. Ecol. Res., 23: 607-614. doi:10.1007/s11284-007-0414-8Furthermore, Japanese walnut (''Juglans ailanthifolia'') is an important food for Japanese squirrels in lowland mixed-species forests in Japan. Japanese squirrels 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.

References

External links

* Endemic mammals of Japan Sciurus Mammals described in 1844 Taxonomy articles created by Polbot {{Squirrel-stub