The Secret Life of The Red Squirrel - Full Documentary

Squirrels have lived in Europe's forests for over 30 million years. The name squirrel originates from Latin and means little shadow tail, which is appropriate because red squirrels are small, elusive and sometimes appear to be little more than flying tails. The squirrels are divided into three groups, the ground squirrels, the flying squirrels and the arboreal or tree squirrels. Red squirrels are tree squirrels. The amount of food around has a huge impact on red squirrels. In good years survival is high and their numbers grow, but when food is in short supply they often starve. Red squirrels need to eat between 80 and 100 calories a day. To put that in perspective, there are 7 calories in a single almond and 9 calories in a single hazelnut. So each day they'd need to eat the equivalent calories of 10 hazelnuts or 12 almonds. These of course are high calorie foods and they'd need a mixed diet to stay healthy. Because starvation is a constant threat, food availability determines where red squirrels can be found. They move regularly and follow the food as it comes into season. In spring they'll feed on buds, emerging shoots and rarely they can even eat birds' eggs and chicks. In summer and autumn, seeds, flowers, insects and fruits are common. The fruits red squirrels enjoy include apples, plums, pears, red and black berries, blueberries, raspberries, cherries, strawberries and even gooseberries. In autumn the squirrels spend a lot of time down on the forest floor feeding on mushrooms. The mushroom bloom is one of the most beautiful times in the forest. A red squirrel's weight changes throughout the year. They're at their heaviest in early winter and weigh the least in early spring. On average they lose 10% of their body weight over the harsh winter months. Tree seeds make up the majority of the squirrel's diet. They enjoy spruce, hazel, beech, horse chestnut, pine and oak. Acorns have a high level of tannins and so aren't ideal for the reds in large quantities, but they're regularly seen eating them and seem to enjoy them as a seasonal variety. Squirrels will also graze on the lichens and mosses that grow on the trees between the clusters of acorns. Higher calorie nuts are taken in preference of lower calorie options. For example, in feeders red squirrels will dig through the almonds to get to the more calorie-rich hazelnuts, only taking almonds when the supplies are low. One of the squirrel's many charms is its highly inquisitive nature, so you need to make sure your camera's secured down. Luckily for me it wasn't too far away. Red squirrels can access water from the safety of the trees by drinking dew or raindrops from the tree. During hot weather they're often forced down from the canopy to drink directly from puddles, ponds or streams to get the water they need. To get additional calcium, red squirrels will often gnaw on deer antlers and bones. You can tell when you're passing through the home range of red squirrels because they often feed in the same place, somewhere raised off the ground slightly so they can keep an eye on the surrounding forest while they eat. These feeding stations are often littered with the remains of their recent meals. Sometimes squirrels accidentally drop a seed and a young tree will grow where it fell. Pine cones can be hard to open, but they're a good source of food, and so different woodland animals have developed their own specialised ways of breaking into them. The pine cone seeds are tiny, each one equipped with its own dispersal wing. If you find a cone in the woods you can tell which creature ate it by the way it's been stripped. Wood mice and voles strip the cones right back to the centre. They can cut much closer because of their smaller teeth. Woodpeckers hammer at the cones, smashing the seeds up. They often wedge the cone into a crack to hold it in place before smashing it apart. Red squirrels will use the scales on the end of the cone, as they use this part to hold the cone as they turn it and tear off the scales with their teeth. Similar to people, red squirrels have been shown to be either left or right handed. You can even tell by the angle of the cuts if it was a left or right handed squirrel that ate it. These skills are essential because pine cones have evolved to protect the tree's seeds. In cold, wet weather the cone absorbs water and closes up, protecting the seeds. You can see this yourself by dropping a pine cone into water. In warm, dry weather the water evaporates and the cones open up so the seeds can be dispersed. But drying out can take three days, so I've illustrated it here by reversing the clip. Because red squirrels don't hibernate, they have to find a way to survive the winter months. They do this by caching. They hide food to eat later when it's too cold to be out for long periods and food is difficult to find. Red squirrels need to cache enough food during the autumn months to keep them going through the winter. They can hide thousands of individual food items a year and remember where most of them are hidden. But inevitably some are forgotten over time. This over-caching actually helps to preserve the forest that they need for their own survival as they plant large numbers of trees and are important for the dispersal of many tree species. Red squirrels also help to spread vital fungal spores in their faeces. Squirrels use landmarks to hide and later locate their caches. Once they know they're close they can use smell to pinpoint the food. A red squirrel can smell a hazelnut from around 30cm away. Squirrels remember not only where they buried something but also what type of food is buried there. This enables them to collect the perishable foods first and leave the longer lasting food items buried so they can efficiently harvest their stash with minimal waste. So they don't forget where everything is they'll often go back to a previous cache and move it to refresh their memory. It's not just predators that the squirrels have to look out for. Clever woodland jays will follow and watch squirrels and steal the nuts they hide. They don't waste time on the dried up lighter nuts and focus on the heavier, higher calorie pieces. Once the reds have raided the nuts in their paws they take extra care of the best morsels. They make a special effort with these high quality items, burrowing them further apart to keep them safer from raids. Squirrels don't just sort nuts by quality. There's also evidence that they sort food by type so they know exactly where to look later to get what they need. Red squirrels make a risk reward calculation. They know that nuts buried in safer areas are more likely to be found by other squirrels who can take their time finding them. Caches hidden in dangerous places however are much safer. To a red squirrel open ground is a dangerous place. This plan works well because other passing squirrels won't want to spend as much time in such a predator exposed location. The downside of this is that the squirrel's own safety is put at risk while burrowing and collecting the food. But because it takes the thief longer to find the cache than the owner, this trick can pay off. A bit of stealing is inevitable and squirrels can tolerate some cache theft because they're also stealing the caches of other squirrels and this evens things out. If another squirrel is watching they'll dig a hole and pretend to burrow a nut before sneaking off and hiding the nut out of sight. If a squirrel notices its cache being raided it will move the remaining items. It's better to eat what's left now than have it taken by a rival. Their behaviour also changes with food availability. For example when they're at a squirrel feeder full of hazelnuts they'll spend less time worrying about where to cache and prioritise caching as many nuts as possible. They can carry several nuts at a time and take care to place them exactly in their mouths so they're not dropped as they jump from branch to branch. And they often stop along the way to make minor adjustments. They don't just hide food on the ground. They cache many items up in the trees too, between ivy roots and the main branch or in any nook and cranny they can conceal it in. Anywhere the others won't see it. When all other holes are filled they even try to hide a few behind the feeder. Hiding food underground can be a problem because the food needs to be prepared so it doesn't rot. Squirrels break up fungi and hang them in the trees. They're left up in the trees to dry for several days. Only once they're thoroughly dried out are they collected and cached. Red squirrels don't defend a territory but they do have a home range. And the home range varies in size depending on how much food's around. If food resources are high then the home range can be as small as 12 acres. But in other areas where there are fewer food resources the home range has to be much larger, closer to 120 acres. The home range needs to include a water source so they can find a drink in hot weather. Although red squirrels are generally solitary they do encounter other squirrels regularly. Their home ranges overlap and a dominance hierarchy is established between neighbours. Because of this hierarchy fights between red squirrels are rare. Usually tail wagging and foot stomping is enough. But when fights do break out squirrels can be injured and have torn ears or missing fur. Red squirrels are opportunists and follow food crops as they shift through the seasons in the forest. They seek out and spend time in the most food dense areas of each period. They often establish routines, travelling along the same routes and even jumping from the same branches along the way. As they go they scent mark their route with glands in their cheeks. Red squirrels can jump through the trees for hours and they're amazing fun to watch. A red squirrel's body is shaped by life in the trees. The safety provided by the cover of the canopy is matched by the constant danger of the fall. When they make a jump they need to be sure every time because one fall could be fatal. For this reason tree squirrels like the red squirrel have evolved bigger brains than ground squirrels. This extra brain power allows them to be quick thinking and manage the complex decisions needed to jump from branch to branch through the canopy. Squirrels have groups of whiskers scattered in different places on their body. These sensitive hairs give them information about wind speed and direction before a jump and help them avoid collisions while moving quickly through the branches. Tree squirrels also have longer limbs and more slender bones than ground squirrels. They've evolved to be light and agile. This lightness helps them move fast but it also allows them to get out onto the lighter branches to escape predators and find extra food. The hind legs provide the power for jumping. Before a jump the squirrel lets go of the branch with the front paws and then pushes off the branch with the powerful hind legs. The smaller front paws have large pads especially on the landing wrist area where they help absorb the shock and impact of the landing. The larger back feet have reduced pads so all the energy is used for the jump and not absorbed by the pads. Like pine mines red squirrels can turn their back foot around and walk down a tree trunk hanging from the rotated back foot. Red squirrels climb using their claws as hooks to grip the tree. Each paw anchoring them as they go. Red squirrels have an unusually short thumb. They use these to hold small food items, spinning them quickly between bites. The tail is used for balance during climbing and for minor adjustments while flying through the air during a jump. This ability to change course can be life saving as a gust of wind can throw them off course. But the red squirrel's tail has many uses. They can use them as a sun shade in hot weather, as an umbrella in rain and as a winter duvet in the dray. The tail also has a specialised vascular system that controls blood flow to keep them warm in the winter and cool in the summer. The tail is also used for communication. Frustrated squirrels flick their tails. Wagging the tail warns other squirrels that there's a predator in the area. New research even suggests that squirrels have different combinations of tail movements and calls to distinguish between ground predators and aerial predators so they know exactly where to hide. Just like fish and many other animals, red squirrels have evolved counter-shading. Their underbelly is white so when seen from below it blends in with the bright sky camouflaging them from ground predators. When seen by predatory birds from above, the squirrel's back is dark and so blends in with the darker ground below it. Their coat colour also blends in well with the colours of autumn leaves. The red squirrel's eyes are also evolved for life in the trees. With eyes on the sides of their head they have a large range of vision. They can often be seen freezing before moving through a dangerous area with limited cover or open ground. They're carefully scanning their surroundings and checking for the movement of any potential predators before committing. They use their colour vision to select the ripest and best fruits. A red squirrel's eyes have tinted lenses to protect them from the glare of the sun as they jump through the trees. They can't afford for a sudden flush of light to cause them to fall. For this reason their eyes are also adapted to help them see in the lower light levels of the heavy canopy at dawn and dusk. Squirrels have a strong sense of smell and use scent to find cached food and follow and read the information packed scent markings of other squirrels and predators. When you spend time watching them eating you can see that clearly they enjoy the smell of good food as well as the taste. Hearing is also vital for small woodland animals and squirrels can often be seen listening intently to what's happening around them. The colour of a red squirrel can tell you about the climate in which they live. This is because for squirrels colour is linked to thermoregulation. The darker the coat the colder and the more rainfall in the squirrel's home. Lighter coloured red squirrels are from warmer, drier areas. Starvation is the biggest killer of rural squirrels. Domestic cats and cars are the biggest killers of urban squirrels. Cars can be especially dangerous for squirrels. They've evolved to run in a zigzag motion when escaping along the ground. They'll check an area carefully before crossing it. If a predator suddenly appears while they're on the ground they zigzag to confuse it until they get to the safety of a tree. A straight line can mean they're outrun by the predator so they use their agility turning quickly from left to right. This works well for squirrels in the wild but on urban roads it can put them in the path of a car more than once. Not surprisingly red squirrels are difficult to catch. They're too agile and they can escape into the trees. Most ground predators can't climb as well as squirrels and those that do are too heavy to get out onto the lighter branches. Aerial predators can't get to them because they're protected by the surrounding branches and leaves of the canopy. Predators find red squirrels even more difficult to catch because they're only active during daylight hours when many predators are hiding away or sleeping. The red squirrel is always tucked away in the tray long before it gets dark. The population density of red squirrels is also relatively low. All of this means that predators don't specialise in hunting red squirrels and prefer other prey species they can get more easily. Red squirrels know when they're moving out into an area that makes them vulnerable and they're extremely cautious. If it's not safe they don't do it. So red squirrels are mainly caught by opportunistic predators that happen to come across them. The goshawk and the pine marten are their biggest predators but red squirrels are not commonly found in the diet of even these. Studies have shown that red squirrels make up less than 1% of a pine marten's diet. Pine martens preferred mice and voles that were encountered more often, easier to catch and eaten much more readily. Predation in the forest can vary with changing circumstances. For example when a deer dies the carcass can draw in predators temporarily but significantly increasing the numbers of ground and aerial predators in the area. Pine martens and other predators gather to make the most of these easy meals. Studies have shown that pine martens eat more deer than red squirrels. So despite not being specifically targeted red squirrels have to remain cautious. Just because they're not being actively hunted doesn't mean there aren't plenty of predators around who would eat them if they got the chance. When a potential threat appears reds run to the base of a tree and check how serious the situation is from the relative safety of this spot. If it's a false alarm they can climb back down but if it is trouble they can easily escape to the canopy above. Like many other animals in the forest red squirrels have learnt to respond to bird alarm calls as a warning of predators. They take some more seriously than others. They're especially sensitive to the alarm call of the jay. Perhaps because this is one of the loudest and sharpest alarm calls in the forest. Red squirrels were once seen everywhere in the UK and Ireland. In Tudor England deforestation reduced the habitat of the red squirrels and with it their numbers. During the Victorian era people imported and introduced American grey squirrels into their gardens. By the 1930s grey squirrels had spread out across the UK and Ireland. Because of these characteristics red squirrels were often seen in the UK and Ireland. Due to their careless actions the eastern grey squirrel is now considered one of the 100 worst invasive species in the world. Grey squirrels carry squirrel pox which is often fatal to red squirrels. This and the fact that the grey squirrels outcompete the red squirrels for food caused their numbers to crash. Research has shown that the greater the number of grey squirrels in an area the more individuals that carry the pox. The damage the grey squirrels are doing to the reds obviously isn't the fault of the greys. So scientists are looking at ways to reduce the number of grey squirrels without having to harm them by trapping or killing them. One method is contraception which would be given with food to the grey squirrels. Trials of this contraception are about to begin and the scientists think this could be started within the next two years. It's obviously vitally important that this contraception doesn't pass on to birds of prey or red squirrels or any other species. This could be great news for the red squirrels who'd fill the void left behind as the number of grey squirrels dropped. This could also be good news for the woodland as a whole. The relatively high population of grey squirrels causes increased damage to tree bark. They strip the bark to build their trays and to access the sap below which they feed on. Red squirrels also remove bark but the population density of the red squirrels is much lower than the greys so the damage done to trees is much less severe. Grey squirrel damage costs the UK tens of millions per year. The affected trees often die and this is a problem for other species that rely on our woodlands for their own survival. A mature oak tree for example can support over 2,000 other species. Pine martins are also an unexpected hero for the native red squirrel. Pine martins do eat red squirrels, although not in large numbers. Red squirrels evolved alongside the pine martins and so they know how to handle them. Pine martins find it easier to prey on grey squirrels because they spend more time on the ground and they're heavier and slightly less agile in the trees. Because the grey squirrels live in higher population densities, pine martins encounter them much more often. The higher the number of pine martins, the lower the number of greys and as a result the higher the number of red squirrels. But for this to work, pine martin numbers have to be present in sufficiently high densities. At present, pine martin populations in the UK and Italy are not dense enough to stop the spread of the greys and the fall of the reds. But conservation efforts are in place and the numbers are slowly growing. Between the contraception efforts and the return of the pine martins, hopefully we'll be able to see the red squirrels making a comeback in the near future. The red squirrel sleeps and rests in the relative safety of the forest. To do this, they build tree nests called dreys. Dreys can appear small and be hard to spot and they can even look like bird's nests from the ground. Dreys tend to be built close to the tree trunk at the base of a side branch. They're usually around three quarters of the height of the tree and tend to be between 20 and 50 centimetres wide. The entrance to the drey can be blocked up with moss in bad weather. You can tell if a drey is still active because the fresh green moss hasn't lost its colour yet. Red squirrels build multiple dreys within their home range so they can rest along their regular route. They'll also build dreys relatively close together, as little as 30 metres apart in their favourite locations, usually where there's a good source of food. This is vital because if a predator raids the drey or a storm or tree fall destroys the drey, they can quickly find warmth and safety elsewhere. Building a drey can take a red squirrel many hours and they can't afford to be exposed to the danger of the elements or predators at night. Dreys are generally built from twigs, lichen, grasses, leaves and moss. Red squirrels build two types of dreys. Day-resting dreys are thinner, less insulated and take less time to construct. Winter dreys are heavily built to protect against the cold winds and heavy rain. They're very well insulated so provide a warm, dry place to rest during bad winter storms. These heavier dreys are also used as natal dreys to raise the young. Dreys aren't generally found on the edges of the woods as exposure to the wind and predatory birds is dangerous. They're usually built deeper into the woods where surrounding trees reduce the risk of heavy winds and rainfall damaging them. Red squirrels don't sleep in the same place. They stay one step ahead of the predators and move from drey to drey as they pass through their home range. Reds will often grab items they see along the way if they think they'll make ideal nesting material. It's a constant battle against the elements as the dreys are routinely repaired and topped up with bedding. The dreys are especially important to red squirrels during the winter when they're only active for a few hours a day and spend the rest of the time in the warmth of the drey. Squirrels are generally most active in the early mornings and need the dreys to protect them against dangerous predators as darkness falls in the woods around them. Young red squirrels become sexually mature at around 10 months old. There's no visible difference in size, colour or shape between the males and females. The male's testes are abdominal for the majority of the year. They descend in spring and summer ready for mating. The female's eight teats can only be seen when she's lactating. Red squirrels don't form lifelong pair bonds. Instead both females and males have multiple partners throughout their lives. As well as abdominal testes, male squirrels have underdeveloped erectile tissue so the penis is supported instead by a 10mm long baculum bone. The red squirrel mating season is short. The female is only receptive for one day. In the build-up to this are scent changes. This scent change attracts males who gather in the area. As more males gather aggression builds. A number of males chase the female through the trees. Dominant males threaten other males with calls and tail wagging in an attempt to keep them away. Generally the largest male gets the female. After mating the female becomes aggressive towards the male and the young are then raised by the female alone. Squirrel behaviour then returns to normal. In August the male's testicles reduce in weight and return to their abdominal position. Red squirrel gestation lasts for around 40 days. Between 1 and 7 young are born. Baby red squirrels are born blind and hairless. The young are cared for by the mother until they're weaned at 10 weeks old. A female red squirrel will normally successfully rear around 5 young in her lifetime. Squirrels usually have two litters. They mate in January and then around August for a second litter. The most important single factor in the number of youngsters red squirrels are able to successfully rear is food availability. From 8 weeks old the young begin to follow their mother outside the dray and start eating small amounts of solid food. The young squirrels leave their mother to find their own way in a new home range. This usually happens in June or July for spring litters or between September and November for summer litters. Red squirrels molt twice a year. Each molt takes about 6 weeks. The exact timing of the molt depends on the individual and their location. The first molt happens between March and June. This spring molt starts on the head and moves over the body. The second molt happens between September and November. The autumn molt starts at the base of the tail and moves back up in the reverse of the earlier spring molt. The red squirrel's ear tufts and tail hairs only molt once a year around September time. They can live for up to 10 years in captivity and reach 7 years old in the wild. The average lifespan of a red squirrel is between 3 and 4 years. Sadly most die in their first year as being inexperienced in a forest full of predators is extremely dangerous and they need to learn quickly to survive. If you'd like to help red squirrels there are a few things you can do. You can put food out in bird proof squirrel feeders. Try as they might they can't get in so be sure to feed the birds somewhere else nearby. The squirrels quickly learn to open the lid and access the food inside. But it's important to make sure you're not encouraging the squirrels to cross a road to reach them. Squirrel feeders should be set up at human shoulder height to keep them out of reach of domestic cats. It's important there's a clear tree route to the squirrel feeder so they don't have to cross too much open ground. Squirrel feeders shouldn't be used where greys and reds live together as this would likely spread the pox and harm the reds. Peanuts alone can lead to calcium deficiencies in red squirrels so it's important to feed squirrels a mix of chopped raw carrots, chopped apples and a variety of nuts like hazelnuts, almonds and walnuts. If a tree bridge to your squirrel feeder doesn't already exist then you can plant one. Bare root hazel is native, cheap to buy in bulk and the red squirrels love the trees and the seeds they produce. You can also help by putting up a squirrel nest box. Be sure to mount it in a safe place high up in the trees and away from any roads. Always ensure it's securely mounted so storms and heavy winds aren't a threat to those inside. By helping red squirrels you get to spend more time around them and they more than pay for your efforts with the entertainment they provide. Although nature is in constant change, in a way it remains still. Watching a red squirrel in a tree is a universal experience that's unchanged throughout recorded human history. Our native wildlife doesn't just connect us with nature. If you want to connect with Anne Boleyn, Henry VIII or Charles Darwin, then watching a red squirrel is as direct a connection as any of the castles or houses. Like all people who came before and since, they took the time to stand quietly and watch our wildlife too. Thanks for watching!