Siberian Chipmunk: Slippers of the Gods
Siberian Chipmunk Tamias sibiricus otherwise known to the Ainu as Slippers of the Gods
The Japanese Archipelago consists of a divided, fragmented crescent of land. Channels of seawater, some deep, some with strong currents, have long separated the islands and the life that lives on them.
Some of those channels are so ancient as to dictate very strongly the distribution of wildlife in Japan, and one of the most significant of these is the Tsugaru Kaikyo, the strait, which is 20 km wide at its narrowest point and 140-200 m deep, that divides the Japanese main island of Honshu, from Hokkaido further to the north.
So significant is the depth and age of this channel that whole suites of species are divided by it, and major distinctions between the fauna and flora north and south of it are recognised by scientists.
Such biogeographical borders are given special names, perhaps the most famous in the world being Wallace's Line in Indonesia named after one of the two original proponents of evolution by natural selection (the other, of course, being Darwin).
In Japan too we have such lines and the one dividing Honshu from Hokkaido is known as Blakiston's Line, named after the British consul and naturalist Thomas Wright Blakiston who lived in Hakodate.
North of the biogeographical divide of Blakiston's Line occur such notable species as Blakiston's Fish Owl, and Brown Bear. South of Blakiston's Line we find the Japanese Serow, Japanese Giant Salamander, Asiatic Black Bear and the Japanese Macaque.
Some species, such as the Red Fox occur naturally on both sides of the 'line' indicating their much more ancient distributions, or that they have been able to colonize the northern and central parts of Japan successfully and separately more than once from the continent of Asia.
A small selection of species occur both north and south of Blakiston's Line, but not through natural causes. The Japanese Marten, a predatory denizen of the main islands south of the Tsugaru Strait, has been introduced into Hokkaido and currently thrives there mainly in the southwest. Conversely, the vegetarian rodent, the Siberian Chipmunk, considered cute by tourists to Hokkaido, has been introduced into various parts of Honshu, Shikoku and Kyushu.
The northern Japanese summer is a lush, emerald one. It may be less tropical than that hazy, humid season in central and southern Japan; there may be fewer kinds of butterflies, cicadas and other insects, and the vegetation may be less dense and not as advanced, but lush it is, even in Hokkaido.
The northern deciduous woodland canopy shades a thick, clothes-grabbing, shrubby layer, which spans the gap between the leg-snagging dwarf bamboo and the head-cracking branches. All this vegetation helps hide the native wildlife, some of which is already elusive as it is.
A raised log, stump or branch provides a better look out point. Occasionally, to escape disturbance or predators, they do climb trees, but mostly they are at home on the ground.
Sounds of the Japanese Woodland
Listening to bird and cicada song is one easy way of feeling 'in touch' with the movements of some of the hidden woodland creatures, but watching out for other wildlife can be a strain. On days with even just a light breeze the spinning and flicking of moving foliage is enough of a distraction to wear down the alertness of even the keenest naturalist, and in autumn, when leaves are blowing and falling in a riot of colour, then spotting the erratic movement of a small mammal can be well-nigh impossible.
Thank goodness that some animals, as well as birds, announce their presence vocally. While some mammals, such as the Red Fox and the wily weasels and stoats, move speedily and silently through their territories, vegetated or not, others let on to each other exactly where they are, communicating by various means. For a naturalist, knowledge of these sounds can provide a magical 'window' through the dense vegetation, enabling search in the correct direction, at least, for the hidden vocalists.
Ranging from lowland forests to mountain tops, this individual chipmunk lives at the top of Soranuma-dake. There it enjoys commanding views and, receives visitors (hikers) on a daily basis.
It can take ages to track down one particular forest sound, when first encountering it in Hokkaido's forests. A high-pitched squeak, so attenuated as to be almost impossible to pin down, eventually penetrates the senses. Were it not for the fact that it holds a ring of power it might easily be dismissed as merely the squeaking of a vole or shrew hidden in the grasses near one's feet, but this sound seems to come from further away.
Sudden movement is the give away. With a sprint and a jump, this active little creature reveals its presence as it scampers across the forest floor with its tail erect like a flag. It pauses frequently, peers around, commonly dashes along fallen trees and climbs onto weathered and greying tree stumps, using them as look out points to scan it territory.
Siberian Chipmunk Markings
Sitting still for a moment this woodland sprite shows off its features. A small, mostly terrestrial squirrel, with a long tail (almost the same length as the body), the Siberian Chipmunk is pale to mid-sandy-brown above, with five prominent dark brown stripes running along the face, neck and body.
Between the dark stripes the fur is pale, almost white, and the under parts, from chin to belly and including the insides of the legs, are creamy white. The face is elongate, the snout rounded, the eyes protrude and are black. The short muzzle is pink with long whiskers. The ears are short, rounded, erect and fringed with white. The limbs are of medium length, sandy brown, with short slender fingers and long slender toes. After its stripy back, it is usually the large dark eyes that a new observer notices first.
The striped coat of the Siberian Chipmunk is distinctive when the animal is in the open, but provides suitable camouflage when amongst vegetation or dappled light.
Where visitors are frequent, chipmunks become used to human presence and to hand-outs - here in the form of sunflower seeds. Such close encounters provide ideal opportunities to admire their small rounded ears and relatively huge eyes.
The Siberian Chipmunk, with its stripy markings, its small rounded ears, relatively large limpid eyes and straight, trailing, furry tail it cannot be confused with the true squirrel of Hokkaido, the bushy-tailed Eurasian Red Squirrel or Ezo-risu, though it belongs to the same family, known as the Sciuridae.
The grey-fringed tail, when it dangles down over the tipped face of a tree stump, seems longer than the hunched brown body, and the perky-faced head with its large eyes and rounded ears, seems over-sized. This cute little creature measured a mere 12-17 cm with an additional 8-15 cm of tail. It bobs down from its alert posture and, in a flash it is gone - like a magical sprite.
Then, it re-appears, again as if by magic on a different part of the well-vegetated woodland floor, and then an instant later on an exposed rock. Erratic dashes are interspersed with sudden hesitant, watchful pauses. Abruptly it stands upright, bracing itself on the tripod of its tail and hind legs. The hind feet are long and the hind legs powerful, clearly giving it balance for its bipedal posture. Now its small forepaws are tucked up on its white chest. Suddenly its down and off again; ever watchful for predatory martens, sable, or birds of prey.
This delightful creature, known in the local vernacular as Shima-risu, occurs widely throughout Hokkaido. It can be found in places as diverse as in lowland parks with woodland and bushy understory, such as Nopporo Forest Park just east of Sapporo, on the peaks of low mountains throughout the island, and even high on the stone-pine and rock strewn slopes of the Daisetsu mountains in central Hokkaido, where it can be found at up to 2,000 metres.
While most individuals are shy and retiring, and easily disturbed, some individuals become accustomed to human presence, and presents! These individuals are ready to take full advantage of hikers and visitors to provide them with supplements to their more usual diet of nuts (which they transport in cheek pouches to store up for winter), seeds, tree buds, mushrooms, berries and grains.
Caught in the open, this Siberian Chipmunk adopts the typical 'tail-flag' pose as it dashes for cover.
Life Cycle of the Siberian Chipmunk
A delightful and endearing denizen of Hokkaido's woodlands, the Siberian Chipmunk is active during the day and is typically seen on the ground or climbing in low shrubs. Warm days of summer are when they are the most active, but between late October and April of the following year these seemingly constantly active creatures actually hibernate in an underground burrow that may be two metres or more in length.
After emerging in spring they can be seen rushing across woodland paths and scampering over logs in search of food, or lingering in patches of warming sunlight becoming quite lethargic in the heat. Apart from building up their body reserves again after emerging from the winter sleep, the males must seek out mates.
They have stolen a march on the females somewhat, for by entering hibernation later than females, males can track down the burrows where females have hibernated in the autumn and thus find them again quickly in spring. They usually nest in a burrow or in a hollow log, and gestation lasts about 35-40 days until the litter of 3-7 young is born. Usually only one litter is produced though two are occasionally reared especially in warmer regions where food is plentiful. The young become independent in the season of their birth and they may live for up to five or six years.
When summer temperatures are soaring, it is hard to think ahead to the implications of autumn, yet for several of Japan's native creatures, the pending shift of seasons is more than just a matter of life and death, it is more like a transformation from life to a deathlike state. Japan's largest land mammal, the Brown Bear, and one of its smallest, the Siberian Chipmunk, both spend about half of each year avoiding what they can't survive - winter. And if they are to survive their winter sleep, then they have to work very hard during their months of activity in summer and autumn.
Although both bear and chipmunk have the same end in mind, their strategies and styles of hibernation could hardly be more different. Whereas bears gorge on the rich supply of fish, berries and nuts of summer and autumn, converting food into an insulating and energy-giving layer of body fat, the diminutive chipmunk is too small for this approach.
Brown Bears weigh most in autumn having accumulated large stores of fat, and they burn off their fat as an energy supply throughout the winter. Chipmunks reach their peak weight during summer, and even lose a little weight before hibernation, so their survival through winter depends on food stored in their burrows, not in their bodies, nor beneath their skin. They must wake from time to time during winter to move about, and to eat from their food store.
Relying on its camouflage in the shade beneath a Japanese Stone Pine, this Siberian Chipmunk paused to groom and scratch - important behavior to maintain its fur coat in good condition and to prevent the build up of ectoparasites.
Preparing for Winter Hibernation
The chipmunk's storing behaviour leads to a lot of visible activity in autumn. These cute animals just cannot say no to proffered food. On the crater rim of Hokkaido's beautiful Lake Mashu, one can witness the amusing spectacle of several of these striped pocket-rockets shooting back and forth between their burrows and the feeders where they are plied with sunflower seeds. They snatch, shell, then stuff these seeds into their elastic cheek pouches at an incredible pace, then scurry away with their cheeks bulging almost as large as their head, like cartoon characters suffering from tooth-ache.
Chipmunks are a very familiar sight in North America, where there are more than twenty species (whereas there is only the one in Eurasia), and it is from an Algonquian Indian word that 'chipmunk' has entered the English language. Reportedly it means, 'head first', because that is the way in which they descend trees. To scientists these small squirrels are Tamias (from the Greek meaning "the treasurer") because of their hoards of stored food.
Japan's Shima-risu is tan, with a light brown tail and four light and five dark longitudinal stripes on its body. According to North American folk tales chipmunks did not originally have stripes; they received them from the raking claws of an enraged Brown Bear that the chipmunk had been teasing and tormenting. According to local Ainu legend in Japan, the chipmunks of Hokkaido sprang from the slippers of the gods, which were accidentally left behind when the Earth was made.
In Japan, the Shima-risu can be found only as a native species in Hokkaido. However, they have been introduced into various parts of Honshu (Niigata, Yamanashi and Gifu prefectures), Shikoku and Kyushu. so can be encountered in central and southern parks, gardens and forests too. In Hokkaido, they range from sea level, where they may be encountered even among coastal dunes with their wild roses, through a wide range of forest types and up to the sub-alpine zone where they live among the stunted Japanese Stone Pines.
They can climb quite well, but unlike the almost exclusively arboreal Eurasian Red Squirrel of Hokkaido, the chipmunk lives mostly on the ground, where its movements range from lethargic and confiding to swift and erratic. When in haste, their stripes make them look longer than their diminutive 14 cm suggests, though their 12 cm tail adds to that impression; even fully grown they weigh only 70-115 gm.
Periods of intense stillness intersperse the rapid activity of this attractive rodent. Siberian Chipmunks seem to enjoy basking in sunlight when undisturbed.
This chipmunk is carrying a bundle of leaves and bark in its mouth. No doubt it has a nest nearby and may be ready to give birth.
Shima-risu are active during the daytime, when they feed on the buds of trees and shrubs, on berries, nuts and fungi, occasionally insects and even small birds and lizards. For them the summer is a rush - to breed, to rear young, and then to store food. Yet somehow they survive the severest of Hokkaido's winters - even in the mountains. With conditions in Honshu, Shikoku and Kyushu, where they have been introduced, being so much milder, it is likely that their winter survival rate is higher and that they have opportunities to breed more than once in a year.
During late summer and early autumn each chipmunk must find a burrow in which it can spend the winter. They have a major task ahead of them, and some sex- and status-related jostling to go through too. There is a crucial pattern here: they do not just select burrows at random, nor hibernate where they feel like it. Although the actual date of burrow selection and the start of hibernation vary from year to year, it is always the dominant adult males that select their burrows first, getting the pick of what's available. Those dominant males are closely followed by the adult females, then the juvenile females and finally the juvenile males. What are left for these chimpunks' will be the poorer accommodations, the lowly bachelor pads.
Once the ownership of burrows has been settled, the order shifts, and when its time to hibernate, the adult females begin first, usually at some point in September or October depending on the altitude and weather. Again the date varies from year to year, but the order is fixed. Only after adult females have entered and sealed their hibernation burrows with the characteristic burrow-blocking soil plug, will the adult males enter and block theirs, followed by the juvenile females, and finally the juvenile males. It is unusual to see chipmunks above ground once November arrives. Once they have entered and plugged their burrows they will not emerge again until the following spring, up to six months later. In Hokkaido, the males emerge during the first half of April, up to 20 days before the females. On emerging from hibernation in spring, they are often to be seen dashing across the snow layer from tree-well to tree-well in search of food around the exposed bases of the tree trunks. There are very good reasons why the orders of selecting burrows and of actually hibernating are different, and sex is at the heart of it.
A pregnant female chipmunk resting in the shade beneath a Japanese Stone Pine tree.
As with the cavities and holes used by nesting birds, there is competition for burrows among chipmunks, and adult chipmunks are better able to find and occupy burrows than youngsters. Between selecting their burrows for the winter and actually hibernating, each chipmunk must store up food and nesting material to last at least six months underground.
To gather in sufficient stores they carry supplies to their burrows up to 40 times a day. In Hokkaido, one of their favourite foods for hoarding is the acorn. The large size of these oak seeds means that the chipmunks have to make fewer trips to build up a good store.
The males, because they emerge early, before there is much fresh vegetation available in the forest, must also hoard food in other places to eat in the spring. Where they have been introduced, in parts of southern Japan, it is likely that the warmer climate there allows their period of hibernation to be shorter, and their period of activity each year to be longer.
Close-up the squirrel-like head shape is clear, the grey fringe to the otherwise brown tail is noticeable, and the fine dexterous digits can be discerned.
There is good reason why the hibernating males go to sleep late and rise early. Males live in large home ranges that overlap those of up to ten females. In autumn each male keeps watch on each of the females in his range, and only after he has confirmed the location of the burrows of "his" females will he himself hibernate.
Then in spring, the males emerge early so that they can check again on the females' burrows and be there when they emerge. Each female will only mate on one day each year, about ten days after emerging from hibernation. So with the chances of mating limited to such a very brief period, it is important for males to know where the females are.
If you think that sleeping for up to six months each year is a wasteful approach to life, consider the fact that early relatives of today's chipmunks first roamed the Earth 25 million years ago. Sleeping in is a strategy that works!
Eurasia only has one species of chipmunk, biologists and naturalists call it Tamias sibiricus, but tourists to Hokkaido call it 'Kawaii!' (Cute!).
Text and Photographs: Mark Brazil
A writer, naturalist and wildlife guide, Mark spends half of each year travelling in search of wildlife and the other half writing about it from his base in Hokkaido.
Born and educated in England and Scotland, Mark spent more than ten years involved in the making of natural history documentaries for television, and nine years as a professor of biodiversity of conservation at Rakuno Gakuen University near Sapporo.
He began contributing his column, Wild Watch, to The Japan Times newspaper in April 1982, and has been writing about natural history and travel ever since.
His latest book, a field guide, Birds of East Asia, was published to considerable acclaim in 2009, by A&C Black and Princeton University Press.
You can learn more about Mark and his work via his website: www.japannatureguides.com
Books on Japanese Nature
Siberian Chipmunk: read an introduction to the Siberian Chipmunk, its life cycle, habitat and geographical spread in Japan.