Insular squirrels
THE word squirrel first came into the English language in 1327 and was derived from an Old French word ‘esquerel’. All squirrels are rodents of the family Sciuradae, a term derived from the Greek words ‘skia’ meaning shadow and ‘oura’ meaning tail, which can be interpreted as an animal sitting in the shadow of its tail.
As a youth in England, I knew only red squirrels in the woods near my home but today, my garden bird feeders are regularly raided by cheeky grey squirrels. The largest species of squirrel that I have had close contact with was the Alpine marmoset, on the edge of a glacier in the Austrian Tyrol, where they are locally known as ‘murmeltiers’, the size of a small dog.
On the upper slopes of Mount Kinabalu, I have seen ground squirrels and also a ‘flying’ squirrel at Danum Valley, eastern Sabah, and more recently one at Bukit Timah Nature Reserve in Singapore. To date, only two species of squirrel have been seen in the British Isles. Eurasian red squirrel (Sciurus vulgaris) The Latin term ‘vulgaris’, meaning common, is today a misnomer for this species in the UK. With its reddish brown coat and a creamy-white underside, it moults twice a year to provide camouflage for summer and winter conditions. Throughout most of Europe and Asia, these animals are seen in broadleaf woodlands but today, in Britain, apart from the Isle of Wight, they are more commonly seen in pine forests. Why?
Grey squirrels have taken over the red squirrels’ natural habitat. This scenario is not unlike the simultaneous human invasions of South Africa in the mid-17th century by Dutch, English and Bantus, which pushed out the native tribes (now known as the Bushmen) into the Kalahari and Namib deserts.
There are fewer than 140,000 red squirrels in the UK today, with 85 per cent of the population living in Scotland. In England, the largest population of 3,500 is on the aforementioned Isle of Wight. On this island, strict measures are observed in implementing the 1981 Wildlife Conservation Act, whereby a grey squirrel may be trapped and must be humanely destroyed. Last December, police marksmen were detailed to shoot an American red-tailed hawk that had escaped from captivity and was seeking red squirrels as its prey on this island. Theoretically, red squirrels have become a protected species.
Mostly found in coniferous woodlands, the ‘reds’ feast on pinecone seeds, fungi, berries, hazelnuts and young shoots. They have occasionally been seen eating birds’ eggs. Compared to the grey squirrel, ‘reds’ are heavier at 700 to 800 grams and are thus less agile, despite a smaller head to body length of 19 to 23 centimetres and a tail length of between 15 and 20 centimetres.
Their life expectancy is no more than three to seven years, during which a female will produce no more than two babies a year. Eighty per cent of newborn ‘reds’ do not survive their first winter but hopefully climate change may alter this statistic. The babies are born in a drey (nest) made of twigs and lined with bark, moss and leaves in the forks of branches or in tree hollows. These squirrels hoard their winter provisions in tree holes or bury them underground. It is thought that they have poor spatial memories, often forgetting where their caches are hidden. Eastern grey squirrel (Sciurus carolinensis) An invasive species, first introduced to the British Isles in the very late 19th century from America, it now has reached a population of five million. With a head-to-body length of 23 to 90 centimetres, a tail length of between 19 and 25 centimetres, and weighing only between 400 and 600 grams, they are a fit species.
They have the ability to descend a tree head first and have greater spatial awareness than the native ‘reds’, together with a greater capacity to store body fat. With a litter of normally three babies, they live for several years longer than the ‘reds’. Feeding on acorns (oak tree seeds) they, unlike the ‘reds’, can easily digest them. They can strip the bark off sycamore (acer) and beech (Fagus sylvatica) trees with consummate ease, leading to consequent tree damage.
Regrettably, this species carries a disease, commonly known as ‘squirrel pox’ or Papavox virus, to which they have immunity but it can be transmitted, through infection, to red squirrels and other animals, if they are bitten or scratched leading to death.
Squirrels of all species have very sharp claws. I have witnessed my dog seize a grey squirrel by the nape of its neck as it was feeding on the edge of a ripe barley field. Fortunately, upon my command, my dog dropped the squirrel which scurried up the nearest oak tree, and both animals seemed none the worse for wear. The ‘greys’ face natural predators such as weasels, stoats, buzzards, foxes, cats and dogs, succumbing more often as road casualties yet surviving in such large numbers through their resilience to take over the natural habitats of the ‘reds’. Observations in Borneo In 1869, naturalist Alfred Russel Wallace recorded five species of Sarawakian squirrel. Later, in 1916, Robert Shelford recorded 16 species. A century later, 34 Bornean species have been observed, with most of these in the Mount Kinabalu National Park. Wallace declared that there were no native species of squirrel in Australia but events have overtaken his writings, for humans introduced them there in the late 19th century.
Whilst in Palembang, Sumatra, Wallace joyfully recorded seeing the local people feed these rodents by hand, as they accepted them as their fellow inhabitants through life without hunting for squirrel meat.
Shelford devoted many pages of his book to the Sarawakian squirrels he observed first hand. In size, these varied from a large ‘flying’ species with a 46-centimetre long body and an equally long tail, to much smaller species. He regarded all Bornean squirrels as ‘frugiverous’ apart from one species, Nannosciurus exilis, which he observed “catching winged termites as they emerged from their nests”.
Today, Hans Hazebroek, Tengku Zainal Adlin and Waidi Sinun, in their beautifully illustrated book ‘Maliau Basin – Sabah’s Lost World’, provide valuable insights into the squirrel species observed in Borneo’s remotest interior. Bornean squirrels Here, the squirrel species may be divided into the following three major classes, distinguished by their head-to-body length, weight, habitat and colourings.
1. ‘Flying’ (or more accurately gliding) squirrels with subdivisions into (a) giant gliders with a head-to-body length of more than 30 centimetres and distinctive colourations, (b) medium-sized from 16 to 24 centimetres, (c) small-sized of less than 16 centimetres and (d) pygmy versions, of which two have been seen in Sarawak but not in Sabah. The flanges of skin, on both sides of their bodies, open up to produce wing-like structures which are not unlike those of high risk human fliers sky diving off alpine peaks today.
2. Tree squirrels, which are again identified by sizes and colour from giants (over 25 centimetres), medium (22 to 27 centimetres), smaller (15 to 25 centimetres), even smaller (6.5 to 15 centimetres) to a pygmy group (six to 10 centimetres).
3. Ground squirrels vary considerably in size and so far have not been fully identified.
Most of these three major squirrel groups build their dreys in tree crotches, at different heights in the forests to evade forest floor predators. They can be identified by the position of their habitat from the forest floor up to the canopy of emergent trees and through their bodily colourings ranging from grey-black, redbrown, dark brown, or spotted with brown and black, white patches on their chests and so on.
Four out of five Bornean species of ground squirrel have been spotted on Mount Kinabalu, together with 10 out 14 species ‘gliding’ squirrels. Two distinctive squirrel species there are the whiskered ‘gliding’ squirrel, so called for the wart-like bulge on its cheeks which exhibits projecting long hairs, and the redtailed species which, unlike others, has very prominent ears that are hairless.
I only wish I knew more about the habitats, breeding patterns and food sources of Bornean squirrels but I do know that the vast majority on this, the world’s third largest island, are fruit eaters with only a few omnivorous species eating vegetables and termites with a penchant for ripe durians and cocoa pods. These species are as much despised by Bornean farmers as are the British grey squirrels thanks to their attraction to ripened corn crops in maize, wheat and barley fields.