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Paul Owen
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The Red Squirrel (Sciurus vulgaris)
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Classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Suborder: Sciurognathi
Family: Sciuridae
Subfamily: Sciurinae
Genus: Sciurus
Species: Sciurus vulgaris
Common Names
Common Squirrel
Red or Brown Squirrel Light-tailed Squirrel
Feorag (Scots Gaelic)
Iora Rua (Irish Gaelic)
Though over 40 sub-species have been described, none are currently recognised
Historical Perspective
The Red Squirrel has been described for Millennia, appearing in carvings and mosaics dating back from early Roman and Asian civilisations. Squirrels themselves have their origins some 34 million years ago, around the same time as the oldest known tree squirrel fossil of Protosciurus. Of the 267+ species of squirrel currently described, none look markedly different in form from their common ancestor.
The first signs of the Red Squirrel in the UK, the only species native to the island, did not appear until around the end of the last Ice Age, approximately 10,000 years ago, when the land bridge between the United Kingdom and Europe began to disappear. Records from the 15th and 16th centuries indicate that the numbers of Red Squirrels present in Scotland and Wales were already dropping and that by the 18th century, was virtually extinct in Scotland. This decline has been largely attributed to the timber industry and the subsequent felling of large areas of woodland. The nineteenth century saw a drive to replace many of the trees that had been lost and, coincidentally, boost the Red Squirrel numbers. By the start of the 20th century this policy could be seen to be working and there were thriving populations across the UK. Indeed, they recovered to such a level that the Red Squirrel became recognised as a pest in some areas. Between 1903 and 1933 the Highland Squirrel Club recorded the destruction of 82,000 Red Squirrels.
Unfortunately, the remainder of the twentieth century has seen the population plummet down to its present threatened levels in the United Kingdom. Throughout their range Red Squirrels are listed on the 2000 IUCN Red List as Lower Risk. They are also listed on Appendix III of the Bern Convention and are protected by Schedules 5 and 6 of the Wildlife and Countryside Act. A licence is required from the appropriate agency (English Nature, Scottish National Heritage or the Countryside Council for Wales) for any study in the wild that interferes with them or their nests. The Red Squirrel is also listed as a priority species in the Biodiversity Action Plan. As such they are in need of URGENT conservation action and are a focal species for the Wildlife Trusts. With the exception of northern Italy (where the Grey Squirrel has also been introduced), the Red Squirrel is not threatened anywhere else in its range. This supports the belief that they are being replaced by this non-native species wherever it is introduced.
Geographic Range
Red Squirrels prefer to live in large patches of conifer forests (greater than 50 hectares) and can be found at altitudes up to 2000m (the tree line) in the Alps and Pyrenees. Its range extends throughout the Palaeartic. From Siberia and Scandinavia in the north to the Mediterranean Sea in the south, and from China in the east to the United Kingdom and Portugal in the west. It varies in size throughout its range with the largest individuals found in the most southerly areas.
Within the United Kingdom, the current wild population is estimated at 161,000. Scotland hosts 121,000 of these with 30,000 in England and a further 10,000 in Wales. Though there are isolated pockets to be found in Southern England - Brownsea Island in Dorset, The Isle of Wight, Jersey and Thetford forest in Norfolk, 85% of the Red Squirrel population is in the north where the Grey Squirrel is not yet well established.
The population in northern England is spread throughout Cumbria, Durham, Northumberland and North Lancashire as well as in pockets along the Merseyside coast. The Welsh population is patchy but there is evidence to suggest that numbers on the Isle of Anglesey are growing. Populations in Ireland and in areas of the Scottish highlands are still considered healthy.
Physical Characteristics
The squirrel family itself belongs to the order Rodentia - characterised by their gnawing front teeth. Within this order the family Sciuridae covers three squirrel groupings: Flying Squirrels, Ground dwelling Squirrels and Tree or Arboreal Squirrels. The Red Squirrel Sciurus vulgaris falls into the last grouping.
In terms of its physical appearance throughout its range, it is often considered as one of the most variable mammals in the Palaeartic region.
Head/Body:180-200mm
Tail: 140-200mm
Hind Foot:55mm
Shin Length: 70mm
The hind foot possesses five long digits while the fore foot has four long digits and a very small thumb. Its hind legs are long and powerful with the fore legs being shorter. Body weight varies seasonally and between the sexes but is commonly in the 230-350g region. Red Squirrels have broad heads with pointed muzzles. All squirrels possess powerful jaws with upper and lower ever-growing incisor teeth that have self-sharpening cutting edges.
Red Squirrels also possess excellent eyesight and have a very wide field of vision. They are also capable of distinguishing between vertical objects. Though they are diurnal it is considered likely that they can see quite well in dim light. Their field of vision allows them to see in almost every direction at once but they are almost colour blind.
The tail has a number of functions. At rest, the large bushy tail will be held over its back as a means of thermoregulation and as a signalling device. When stretched out it acts as a balance to the squirrel while it is running and leaping.
Red Squirrels also possess a number of sets of whiskers or Vibrissae. They have four sets on the head, above and below the eyes, on the nose and under the chin. Vibrissae are also found at the base of the tail and around the feet. Combined together the squirrel is very well equipped to assimilate a great deal of information on its immediate surroundings. Red Squirrels also possess an extremely well developed sense of smell. It is used extensively for social communication and distinguishing between territories. It is also very important for the task of locating and distinguishing between various food items and caches.
Longevity
6-7 years maximum in the wild (more commonly 3-5 years). 10-12 years in captivity. Females are sexually mature in around 12 months, males at around 10 months.
Dentition
I1/1,C0/0,P1-2/1,M 3/3 Deciduous lower and second upper premolars are shed at sixteen weeks. Other teeth are not deciduous.
Coat Pelage in Adults
Dorsal: Uniform colour - dark red-brown to brownish-grey. Chestnut in summer. Ear Tufts: Red-brown & thick. Small or absent in summer.
Tail: Dense, dark red-brown. Thinner & chestnut to creamy in summer. Ventral: White or cream.
The dorsal coat colour is variable depending upon their geographical origin. Light red to brown-black, grey and blue-grey have all bee recorded in various parts of their range. Two or three distinct colour morphs may even be found in a single population (red, brown, black), with constant ratios of the different morphs within that population. The tail, feet and ear tufts may be as the dorsal colour or contrasting. The melanic and albino forms are extremely rare in the United Kingdom. A new-born juveniles' coat is usually darker than the adults
The Moult
The body of a Red Squirrel moults twice yearly. In the spring they moult from front to back and in the autumn from back to front. The ears moult once per year with new hairs growing in late summer/autumn through to December. The tail also moults once yearly with new hairs growing in late summer/autumn. In summer the coat is shorter and mainly reddish brown. Between August and November the coat is thicker and a darker brown. The winter coat also covers a larger proportion of the soles of their feet and the ear tufts are much more prominent at this time. The shedding and growing of hair can be delayed or aborted by a lack of food, disease or parasitic infestation during spring or late autumn. If no moulting is seem at these times it could be an indicator of a problem.
Scent Glands
These are associated with large mucous glands on the sides of the mouth and sebaceous glands in the tissue of the lips. Red Squirrels do scent mark branches in their territory. This is accomplished by means of the glands on the cheeks and lips by a process of face-wiping and from urinary and vaginal secretions through anal-dragging. This indicates that, as the Reds scent mark their territory, the cleaning of their enclosure should not be so vigorous as to mask these scents and should be staged or staggered so as not to completely remove the scent from all areas of the enclosure at once. Ideally their branching and environmental enrichment should not be removed en masse and some care should be taken not to substantially alter the scent marks laid down in the immediate vicinity of their nesting areas.
Hibernation
Red Squirrels do NOT hibernate. They are active virtually every day. Though related squirrels will certainly share nests during the coldest times in winter and they experience a weight gain in the autumn time, neither factor would be enough to make hibernation an option. Very bad weather in winter may force the squirrel to remain in the nest for a time but after 2-3 days they are forced out in search of food.
Natural History
Food Habits & Feeding
The natural diet of the Red Squirrel includes a very wide variety of foodstuffs and their diet varies considerably during the year in line with availability. Such considerations should certainly be taken into account when planning out their dietary regime. Red Squirrels are opportunistic foragers in the wild and food related activities can take up 60-80% of their time.
Of all the foods taken, tree seeds are by far the most important. So much so in fact that they are considered an important seed disperser for some species. Their natural diet includes -
Pine Seeds/Nuts, Sweet Chestnuts, Spruce, Larch
Fir, Beech Nuts (Cob Nuts), Walnuts, Hornbeam Seeds
Hazelnuts, Caterpillars & Snails, Acorns (of limited food use due to digestion problems)
Treat items could include strawberries, bilberries, cherries, grapes, mushrooms, toadstools, pine shoots and the occasional egg. Red Squirrels love corn on the cob & can be offered a variety of grain mixes.
Daily Food Intake - Spring: ~ 80g/day Winter: ~35g/day
As a general rule, shoots and flowers are taken mostly in the spring. Nuts and fruits are taken mostly in the autumn and winter. They favour Scots Pinecones though they also enjoy Larch and Spruce. Hazelnuts could also be considered to be one of their favourite food items, though in coniferous forests their dietary staple would be pine-kernels. All the nuts offered should be made available in their shells so as to aid in filing down their ever-growing incisors. During the autumn and winter period it is important to allow your squirrels to put on weight. They are then in good condition to survive the winter and are also able to survive the rigours of producing young. Extra food should be made available at this time to allow for this. Ordinarily you would expect a 10-15% weight gain in autumn.
They will also enjoy very limited quantities of unsalted peanuts and sunflower seeds. Red Squirrels will also take a wide variety of other items, including - Rose Hips, Lichen, Fungi, Flowers, Berries, Shoots, Buds, occasional Birds eggs & insects. If insects are offered it is important to either gut load them with a proprietary insect diet or else sprinkle them with an insect dusting powder. This serves to balance the Calcium-Phosphorous ratio in what the squirrel ingests. There is little value in offering maize or wheat as they will more often than not be refused. An ideal addition to their diet would be various berries. These will be taken with relish, especially hawthorn berries.
Ideally a captive squirrel would be offered as wide a variety of foodstuffs as possible of a similar composition to those found in the wild and the relative abundance's of each variety would be varied during the year. Ready mixed diets, available in many pet shops, can serve as a base diet though many vary in quality and tend to be high in peanuts and sunflower seeds which are not advised as anything other than treat items. If they are offered in any quantity or as a dietary staple, an additional source of Calcium must be provided. Such a supplement can be included in a number of ways. A proprietary source can be sprinkled onto their food or mixed into the drinking water. Bone meal can also be added to their dry feed mix as can ground cuttlefish bones. Other options would include hanging cuttlefish bones or antlers from the roof of their enclosure. Supplementing the diet is extremely useful during the summer months as it helps in balancing the diets of any juveniles present and helps the mother to regain her strength.
Supplement Recommendations
· Probiotic & broad spectrum vitamin & mineral supplements - Twice Weekly.
· Calcium Supplements (powdered) weekly, or given permanently as antler or cuttlefish bone.
· Calcium Lactate - A calcium supplement that is added to water.
· Zolcal D - A calcium and vitamin D supplement, again added to water.
Another possibility is that a Calcium supplement such as Nutrobal can be mixed with a little sunflower or peanut oil and poured sparingly over their favourite treats. Nutrobal is readily available in most reptile shops.
Other Considerations
Fruits and vegetables should also be offered in regulated quantities, making sure they are free from pesticides. Carrots, grapes, cherries and apples make excellent additions but will not be taken by all. An effort should be made to avoid the use of sweet, dried foodstuffs. They can be offered sparingly as treats, however items such as raisins, sultanas, glazed cherries etc… can cause a calcium deficiency if fed to excess.
It is useful to feed in a manner that complements their inquisitive nature. Ideally it can be spread around a number of containers, with additional items placed in nooks and crannies in and around their branches and tree stumps. Ideally, a large proportion of their food will be offered as high up in their enclosure as possible. Some should also be scattered on the ground (nuts in shells) as this will provide an additional source of environmental enrichment. Feeders should also be kept scrupulously clean and replenished often as mould can be a common problem on a number of their staple dietary items. Feeders should not be placed to near their nest boxes so as to encourage foraging and increase their activity levels.
Nuts and seeds are not always eaten immediately and much of what is offered will be cached. It is therefore quite feasible to provide reasonably large quantities of these as a means of environmental enrichment. Though you will need to look out for signs of obesity you can be reasonably safe in the knowledge that they squirrels will not be over-feeding. Indeed, encouraging this caching behaviour can be an important source of stimulation and exercise in a captive environment. The same thing also applies to bedding materials for the nest. Various materials should be offered regularly so that they may elaborate upon, improve and replace portions as they see fit.
As to their caches, it is important not to remove them unless they are mouldy or it becomes necessary for other reasons. The squirrel is more than capable of identifying and remembering the locations of thousands of caches and is sure to notice if any are removed. They may even exhibit signs of stress if too many are removed at any one time.
Red Squirrels have a specialised technique for opening nuts that utilises the power of their lower incisors. They are more than capable of opening a shell and extracting the nut in only a few seconds. In fact, one Siberian Red Squirrel was seen to strip 190 pine cones in a single day.
In the wild fungi is cached in pits in the ground or left to dry out between tree branches. Seeds are commonly cached by scatter-hoarding. This means that 1-4 seeds are cached in shallow pits, making for an extremely large number of caches. Most of these caches will be located in close proximity to each other. In their enclosure such behaviour is to be encouraged and the use of a floor material not prone to rotting would greatly assist the squirrel. If the floor material is turf, this should not be treated with any pesticides or similar substances as they may have a tendency to leach into any food cached there.
The squirrels are also quite capable of hanging upside down by the tips of their toes and then stretching down for food. This behaviour can be exploited in your feeding regime as an addition to their environmental enrichment and food placement ideas. Red Squirrels will also search meticulously for food items and due to their excellent sense of smell, every item is likely to be found.
Though in the wild they will usually carry their food away from the source and consume it in a safe location, in captivity they tame over time and will become bold enough to take items directly from your hand.
Red Squirrels can often be seen telling good nuts from rotten ones by weighing and shaking them in their paws. If the nut is rotten then the kernel is likely to be small and shrivelled and not worth eating. They also have a unique method of stripping a conifer cone. The squirrel will usually hold the top in one paw and the base in the other, then it rotates the cone and bites off the scales to get at the seeds inside.
Reproduction
The female has 4-6 pairs of nipples and her reproductive tract is Y-shaped. During the breeding season the males testes are large and the scrotal sack is evident. At such times the scrotal sack may be stained dark. Otherwise there is minimal sexual dimorphism between the sexes, making them difficult to distinguish from a distance. The uro-genital distance is greater in males (~10mm)
Mating Behaviour & Courtship
The Red Squirrel is a promiscuous species with little courtship observed other than the chase. The usually non-gregarious males gather in the females home range when she comes into oestrus. After mating they disperse back to their own territories. However, as many males may congregate on the home range of a single female, fighting is a common occurrence.
In the wild, mating chases are commonly seen in January and February. Several males may then be seen giving chase to a single female that is ready to mate. These chases are fast and furious and quite spectacular to watch. They are often characterised by huge leaps through the canopy and spiralling up and down tree trunks.
The home ranges of males tend to increase during the breeding season but those of females do not. Essentially, the males will increase their home ranges so that they overlap with those of females coming into oestrus. As with the majority of tree squirrels, the Reds as promiscuous. The males will attempt to mate with more than one female and not infrequently, the females will mate with more than one male. There is also no long-lasting pair bond between any mating pair.
Mating time is determined by the oestrus cycle of the female, the onset of which occurs over the period of a few days. During oestrus the males will approach the female and follow her for anything up to twenty minutes. As the female is only in heat for a single day a mating chase with the female and various males will take up most of that day. It is also not uncommon to see her being chased around by two or more males at the same time.
When a female has finally accepted a male as a mate and is receptive to him, she moves in front of the male and adopts a copulatory position. In this she crouches on all fours with her tail over her back and held to one side. The first male to reach her in this position is then allowed to mount her immediately.
Parturition/Birth
Two peaks - February to April and May to August. A delay in, or absence of, the first breeding may occur if supplies of seed foodstuffs are poor. Yearling females will almost certainly only have a single litter in their first breeding season. Young are tended to by the female only. In extremely good years some females have been known to have three litters of as many as eight young in a single season. The male can stay with the female at this time as long as separate nesting areas are available.
Gestation
38-39 days
Neonatal Development
Birth: Blind and naked (8-12g at birth, averaging 8.5g)
8-9 Days: Dorsal skin pigmented, hairs start to emerge
21 Days: Hair covering body
19-21 Days: Lower incisors appear
31-42 Days: Upper incisors appear
28-35 Days: Ears open
28-30 Days: Eyes open (Start cleaning themselves around this time)
~ 7 Weeks: Exploring & leaving nest. Eating some solids. Miniature versions of their parents.
8-10 Weeks: Fully weaned
3-4 Months: Gains adult coat
The auditory canals are unopened at birth, with the ears being underdeveloped and lying flat against their heads. Milk is produced for 8-10 weeks. The young are tended to by the mother only. Females stay very close to the young for the first week after birth. Females are known to cover the young with bedding material when they leave the nest. If disturbed she may even carry the youngsters in her mouth to a new or alternate nesting site. The maternal instinct often remains after weaning with the mother watching over and protecting her young.
Females will deter other squirrels from entering their home ranges when suckling. Though there is some spring & summer dispersal, juveniles and young adults usually disperse in the autumn.
The mortality rate is quite high in the wild due to heavy predation by birds and other mammals. Less than one in four survives through their first year in the wild. Young squirrels learn what food sources to eat from their mothers and as they get older they become more reluctant to accept new and strange food sources. It is therefore advisable to wean them onto as wide a range of dietary items as possible early on in their lives.
Oestrus/Ovulation
Polyoestrous. The females are in heat for a single day per cycle. Post-partum oestrus is delayed until the juveniles are nearly weaned.
Litter Size
Though litters as small as one and as large as ten have been observed, 3-5 kittens is the norm. This drops to 2-3 in very young females. The average for spring litters is 3.0 and for summer litters it is 3.6. The survival of young squirrels is determined largely by their first winter. Up to 85% of young are known to perish in harsh conditions.
Behaviour
Activity Patterns
Red squirrels are highly arboreal and are extremely adept at jumping and climbing. They are also extremely agile and easily speed along thin branches. They will come to ground as required in order to forage and bury food. Red Squirrels are also accomplished swimmers and are either left or right handed. They enjoy leaping and racing up and down tree trunks so an attempt should be made to cater for such behaviour in their enclosure.
Their activity levels are noticeably reduced in very hot or very cold weather as well as during periods of high winds and heavy rain. They do not hibernate but during the winter months they may stay in their nests for several days at a time if the weather is stormy or very cold. In periods of very warm weather they have also been known to lie stretched out on a branch in order to keep cool.
Red Squirrels have a wide range of vocalisations (various chatters and shrieks) and also engage in foot-tapping/drumming when agitated or angry. They will usually take flight if frightened. Their tail movements can also be an indicator of mood.
Red squirrels are diurnal and their daily activity cycle begins at sunrise. During the summer months their times of peak activity are early morning (2-4 hours after sunrise) and late afternoon (2-4 hours before sunset). In winter they are most active in late morning. They may also be active at other times of day but this is highly variable. In effect, most of their activity cycle is determined by a trade-off between resting in the nest to conserve energy and its foraging and feeding activities. Their activity patterns are variable throughout the year and are influenced by day length, temperature, weather conditions and food availability. During the winter months, squirrels usually leave the nest at sunrise and limit their activity to a few hours. During this time they will feed on pine seeds and other high energy food sources. More time is spent active during the spring, mirroring the increase in day lengths and temperatures as well as the marked decrease in the abundance of its primary food sources. In the warmer May-October months a bimodal activity pattern is evident with the Red Squirrels again emerging to forage at first light. This is followed by a resting period during the higher midday temperatures and another bout of activity is seen in the late afternoon.
Red Squirrels are usually solitary only coming together to mate. However, they are not averse to social interactions and are quite tolerant of each other. Dominance hierarchies do exist among and between the sexes. The most dominant individuals are commonly larger and older. It is also common for more dominant animals to have larger home ranges.
It is perfectly feasible, in a captive situation, to keep several pairs together as long as the aviary is large enough to give each individual enough space.
Handling
The handling and examination of Red Squirrels is not advised. As they are strong biters there is a danger of injury to the handler from their long sharp teeth. Interaction does become possible with many individuals as they become more familiar with and trusting of the handler. Hand feeding, for example, is to be expected after the squirrels are acclimated to their enclosure. Some individuals may become confident enough to use a person as a climbing frame.
It is suggested that if a thorough medical examination is required or anaesthetic is needed, it should be administered in an anaesthetic chamber. Isofluaine is the anaesthetic of choice. It is also advisable to wear gloves for physical examinations. Trapping should be accomplished with the aid of a long soft net. Grasp the head and neck area firmly through the net before carefully working the net off the animal and moving to a transport container. Use a very fine mesh net to minimise damage to limbs and claws. Do not catch the squirrel by the tail as the skin may strip off. Ideally it's rim should be padded. Wire cat carriers make good transport containers. Cardboard or wooden boxes should be avoided as they will be gnawed through in very short order.
Bites can reach the bone
Wear gloves unless the squirrel is tame
Habitat
In principle, Red Squirrels can find enough to eat in both coniferous and deciduous woodlands and may make their nests in either. However, they are far more successful in coniferous woods. Red Squirrels are extremely well adapted to their preferred coniferous woodland habitats. Their light weight and agility enables them to reach the thinnest branches at the tops of the trees. If found in open fields, moorlands etc it is usually a sign that they are searching for a more suitable home, or simply just lost. They usually prefer to live in large mature trees. Trees chosen as nesting sites will usually have hollowed out sections or other gaps in their trunks.
Red Squirrels may make their homes in a natural tree hollow (Den) or construct their own (Drey). If using a Den (any suitably sized tree hollow, this may be natural or made by a woodpecker) the squirrel will line it with soft and warm leaves, grasses, thistledown and mosses. Once the Den is lined they provide excellent safe havens for the squirrel to keep warm and shelter from the elements. Dens are not often seen. It is more common that their existence is inferred by seeing a squirrel disappear into a tree.
A Drey is a waterproof ball shaped nest constructed by the Squirrel. This is normally located in the cleft of a tree though some appear in the crown. They are usually situated very high up in the tree (5m+). The squirrel manipulates twigs and sticks to form the structure. It is built with a hollow centre (the inner cavity is 12-16cm in diameter and any nest boxes offered should be of approximately the same dimensions) that can be filled with a soft lining in the same way as a Den.
They do not always hunt for broken twigs but will often nibble away at fresh branches that appear to suit their needs. They then insert them into the Drey with their teeth and front paws. A very well made Drey may even last for 2-3 years. Good positioning assists in its longevity. Locating the Drey in the cleft of a tree protects it from the elements due to increased leaf cover. The branches also move less there making it unlikely that the nest will be blown or shaken apart. Red Squirrels will also commonly maintain several nests, the best of which will be used for several years. They will commonly move between them every few days. This strategy has a number of advantages as it gives them a ready alternative home if their nest becomes wet or is destroyed by the elements. It is also a helpful tactic when seeking to reduce the levels of parasitic infestations as they are able to move on and leave them to die out in the old nest. It is also a useful tactic for predator evasion as they are able to escape to a new location and remain there.
Red Squirrels feel far more comfortable high up from the ground and the ability to maintain their distance, if they choose to do so, is an essential element of their enclosure. It in the wild, this also makes it less likely that they will fall prey to foxes, cats and other predators (stoats have been know to take young squirrels). Red Squirrels may also construct summer style Dreys. These are usually flatter structures and offer less protection from the elements. They are used for resting during daylight hours.
Considering their activity patterns and preferred habitats, enclosures for Red Squirrels should be as large and as high as possible (10-12ft high would be an acceptable minimum). A number of branches should be included as should stout trunks that reach the ground. Tunnels, ropes etc… are all useful additions and serve to enrich their environment. Ideally, two or more nesting boxes will be available to each squirrel in the enclosure and bedding materials, twigs and branches should also be offered so they may the option of constructing their own nests. A heated area is not necessary but their nest boxes should be angled away from wind and positioned so that rain does not fall directly onto them.
Home Ranges
The Range Size is the area over which an animal moves during the course of its normal daily activities. Home ranges average 7.4 hectares but there is considerable variation in size as well as overlap between individual ranges. He range size is affected by many factors including, sex, age, time of year, population density, food supply and habitat type. Home ranges are larger in deciduous forests than in coniferous forests, illustrating the greater difficulty they have in obtaining sufficient food there.
Red Squirrels are not territorial. Male home ranges overlap with female home ranges, though adult males tend to have larger home ranges than adult females. Young and juvenile squirrels tend to occupy a home range of similar size to those of adult females.
Threats
Their main predators in the wild are Goshawks and Pine Martens. Domestic cats have also been known to kill Red Squirrels in urban areas. In certain parts of the country, road traffic is also considered to be a major contributor to Red Squirrel deaths.
Grey v Red Squirrels & Conservation Concerns
The root of the problem is that Grey and Red Squirrels occupy very similar ecological niches. The Grey is quite capable of feeding on large seeds from broad-leaved trees giving it a competitive advantage over the Reds. Their ability to feed on these seeds before they are fully ripe, and gain more nutritional benefit from them allows them to out-compete the Reds in any shared habitats. This, and other factors, has had a devastating effect on Red Squirrel populations in the United Kingdom. At present the Grey Squirrel population stands at 2,520,000 with two million of these being found in England, where they outnumber the Red Squirrel by 66:1.
The Grey Squirrel (Sciurus carolinensis) is native to North America and was first introduced to this country in 1876. The first Grey squirrel releases were in Henbury Park, Cheshire, by a Mr Brocklehurst. The first releases' in Scotland came in 1892 at sites including Edinburgh zoo. Studies suggest that fifteen years is all it takes for Reds to be completely eradicated from such forests.
While Red Squirrel numbers have fluctuated in the past they are currently in decline. In the past 100 years their range has experienced a dramatic contraction and they are now, except for a few isolated pockets, rarely seen outside their strongholds in northern England and Scotland. The threats to the Red Squirrel most certainly include the fragmentation of their native habitat and disease. However, the biggest threat by far appears to be the prolific Grey Squirrel. Though smaller in size it is heavier and stockier and is quite bold in character, frequently being seen on the ground. They will not normally attack Red Squirrels.
Factors affecting their decline
Cyclical variations in food availability
Disease epidemics (Parapox Virus)
Habitat loss and the increasing fragmentation of woodlands
Human persecution (e.g. bark stripping in commercial forests)
There is some evidence that Red Squirrels were declining in some areas prior to the introduction of Grey Squirrels. However, another critical factor appears to be the differing food sources available in coniferous and broad-leaved woodlands and the varying efficiency with which the Reds and Greys utilise these resources. By way of comparison Red Squirrels are know to live at population densities of 0.4 to 1.2 squirrels per hectare both in coniferous and broad-leaved forests. Greys also live at these densities in conifer forests (though they have difficulty surviving in very large [2000ha+] purely coniferous areas) but reach densities of 2-8 per hectare in broad-leaved woodland habitats.
The continued survival of the Red Squirrel in this country will certainly depend upon the proper management of our remaining conifer forests as well as on the management of the expanding Grey Squirrel population.
Though now protected in the UK, a hundred years ago there was a concerted campaign to eliminate them from Scotland based on the damage they could do to trees. Both Red and Grey Squirrels strip bark to get at the sap (Red prefer trees in the 10-40 year old range). If they leave a stripped ring around the trunk the tree will soon die.
There was extreme woodland felling between 1914 and 1945 with the felling of vast numbers of Scots Pine and Norway Spruce. They were later replaced with Sitka spruce resulting in a limited and unpredictable food supply for the Reds. Their habitat was further fragmented by the loss of over 50% of hedgerow habitat from the 1940's to the 1980's. This has lead to increasing habitat fragmentation and further isolation of the remaining populations. It has also increased the risk from predation as they are now forced to cross open areas more frequently.
Coniferous woodlands offer the greatest potential for supporting the Red Squirrel in the presence of the Grey's expansion, as small seeded conifers are less favoured by them. Areas of large seeded broad-leaved trees attract Grey's, so new plantings of broad-leaved species within or adjacent to large areas of coniferous woodland should use small seeded species such as Rowan (Sorbus aucuparia) or Ash (Fraxinus excelsior) where possible.
Illnesses & Diseases
Young Red Squirrels in particular (though it can also affect adults) can suffer from a Calcium deficiency if fed often on inappropriate foodstuffs. Medically this is called Metabolic Bone Disease and develops as a consequence of a Calcium/Phosphorous imbalance in their diet. Observable signs include - lethargy, general weakness, weight-loss and spine curvature. The most common cause of the problem is excessive feeding of peanuts and sunflower seeds. It can be easily prevented, by feeding a balanced diet. It is also advisable to include a scientifically balanced item in their diet, for example, Mazuri Rodent Pellets.
Parapox Virus
This disease is invariably fatal to Red Squirrels but its exact origins remain unknown. It was first confirmed in East Anglia in the 1980's and has since spread with confirmed cases in Lancashire (1995-96), Cumbria (1998) and Durham & Northumberland (1999). The current feeling is that where it exists, it is a significant contributing factor to the decline in Red Squirrel populations.
Parapox causes skin ulcers, lesions and scabs with swelling and discharge around the eyes, mouth, feet and genitalia. The squirrel becomes increasingly lethargic as the disease progresses. Though there is no know cure and it is invariably fatal, recovery has been observed in a few individuals. However, this does not seem to confer any future immunity to the individual.
Parapox is endemic in many Grey Squirrel populations but very rarely results in death. The likelihood therefore is that these populations act as hosts for as virus that results in death if passed to Reds. It is thought that, in the wild, infections are passed on through contact at a feeder. So, if there are Greys in your area and your Red Squirrels have access to an outdoor aviary it is advisable that any feeders are placed out of reach of any passing Grey's.
Coccidiosis (Eimeria Sciurorum)
This is caused by a parasitic pathogen that lives in the gut and is commonly found in faeces. It can be treated with Sulphonamides. It is thought to have contributed to the dramatic decline in numbers between 1900 & 1925 from which they have never recovered.
Red Squirrels can also carry a variety of relatively harmless internal and external parasites. These commonly include lice, ticks and mites. These can all be easily treated if they present a problem. Fleas (Monospyllus Sciurorum) can develop into an infestation if the nesting area is not kept clean and the squirrel is not afforded the opportunity to move from one nesting site to another at regular intervals. Ideally, two or more nest boxes should be available for each squirrel. Plenty of dry bedding should be offered and supplemented regularly. If found, fleas can be encountered with Pyrethrum based powders. If antibiotics are offered for any problem then a probiotic should also be made available (on food or in water) to reduce the risks associated with upsets to the gut flora.
Hand Rearing
General Care
If the young are abandoned or the mother dies it will be necessary to hand rear the young kittens. If this becomes necessary it is a worthwhile exercise to keep notes so as to simplify the process second time around.
When the youngsters are taken in, the first action should be to weigh them and make a note for future reference/comparison. Weight gain is a good indicator that hand-rearing is progressing well, and should be repeated and noted, ideally, on a daily basis. It is also useful to know the kittens weight in order that feeding quantities can be accurately determined.
As there may be some time lapse between abandonment or death of the mother and the beginning of hand-rearing, warming the kittens and rehydration should be the first priorities, followed by stimulation of the uro-genital area to stimulate urination and defecation. An appropriate rehydration solution (e.g. Lectade) is gradually changed over to the chosen milk substitute over the course of several feedings.
In the general case maintain the kittens at 95F for a hairless body and 90F for a haired infant with the eyes still closed. Reduce the temperature by 5F per week once the eyes are open. A thermometer should be placed in the enclosure to determine the temperature.
Young squirrels have a very poor ability to maintain their own body temperature and are particularly prone to hypothermia, especially when unfurred. They should be kept away from draughts but in an area with good ventilation. Your chosen container should also allow for a temperature gradient to be maintained. This is most easily accomplished by heating the container at one end only. This will allow the kittens to choose the position/temperature at which they feel most comfortable. The container should be sufficiently sizeable to allow for this. A hot water bottle under the bedding, or a heat mat (preferable), are both suitable heat sources. High-sided units are preferred as they prevent the young from escaping of falling out.
Bedding materials should be soft and comfortable and either disposable or easily washed. It is very important that the young squirrels are kept dry and should be changed as often as necessary to prevent soiling. A cardboard box lined with hay, shredded tissues and old socks would be suitable. The box should ideally be covered with a mesh screen to aid ventilation and avoid escapes.
Note that the box temperature should ideally be maintained when the squirrels are being fed. Sharp temperature changes at this stage of development can shock the youngsters
Milk Replacer
Squirrel milk is high in dry matter and high in fat. Options are:-
· Goat's milk with an added Calcium-Phosphorous supplement
· Esbilac or Lamlac (proprietary milk replacers)
· Puppy milk replacers, lambs milk, Lactol
Once you have settled upon a choice, avoid changing it. It is also advisable to boost the kittens' gut flora by adding a probiotic to the milk. When very young the milk should be offered via a pipette or a small syringe. Milk should also be offered warm, ideally at body temperature. Older kits can be fed via a kitten milk bottle with a soft rubber teat. Very young kits will need to be fed often. Every two hours initially decreasing to every four hours at about 3-4 weeks of age (when the eyes first open).
If the kits are only a day or two old offer the warm milk by dripping it onto their lips and waiting for it to be swallowed. Repeat this procedure until no more is taken.
From pipettes, syringes or bottles (graduate from one to the next as the kittens age) the milk should be directed at the roof of the mouth to avoid choking. The throat can also be gently massaged during feeding to encourage swallowing
Feeding Quantities
Generally kittens can be fed 35-40% of their body weight per day with about 25-50ml per Kg being offered per feed.
Young squirrels should be simulated to urinate and defecate at each feed until they are regularly able to do this on their own. Such stimulation should be a very gentle rubbing in the uro-genital area. Damp cotton buds, damp cotton wool or a damp soft paper towel can be used.
There is a definite risk of constipation and urine retention if this is not done regularly.
Weaning
The weaning process begins at about 2-3 weeks of age (when they begin to move around independently). At this stage there are a number of feeding regimes that can be considered. Each has been used with some degree of success.
Start with Farley's Rusks and then move them gradually to a good quality dry puppy food.
Wean onto soft foods initially (bread soaked in milk and/or fruit). When the teeth are out offer items such as bark and dog biscuits to chew on. Then move gradually onto a wider selection of natural food items.
·Dry breakfast cereals (oat or wheat based) and softer nuts can be offered coupled with fruits (grapes, oranges, apples, cherries etc…) and vegetables such as carrots.
Do not offer Peanuts of Sunflower Seeds to the kittens.
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