Grey Squirrel
(Sciurus carolinensis)
Grey squirrels are renowned for their agility, adept climbing and cunning – they can crack open birdfeeders and run along tight-rope washing lines in search of food. They are present all year and are most active early in the morning or in the early evening. Their diet consists of seeds, nuts, acorns, fruit, tree shoots, bark, lichen and fungi.
Grey squirrels are frequent visitors to gardens with bird tables and feeders, becoming a pest for many bird-lovers. They feast on hazelnuts by cracking the shell in half. You may also find pine cones that have been nibbled, leaving what looks like an apple core behind. Grey squirrels hoard their food in numerous small caches for later recovery. Each squirrel is estimated to make several thousand caches each season. Foxes, stoats, birds of prey and pine martens prey on them.
Fascinating fact:
The grey squirrel is one of very few mammalian species that can descend a tree head-first. It does this by turning its feet so the claws of its hind paws are backward-pointing and can grip the tree bark.
Squirrels make a rough nest, called a ‘drey’, of twigs, leaves and strips of bark, high in the tree canopy. Newborn squirrels are called kits, kittens or pups. They are born blind, entirely hairless, and pink. After around a week, the skin begins to darken, followed by its furry coat. All its teeth have formed six weeks after birth, by which time its eyes and ears have also opened. Full adult body mass is achieved 8–9 months after birth.
Conservation issues
Killearn is on the boundary between the territory of the grey squirrel, to the south, and the red squirrel to the north. Grey squirrels are an invasive species, having been introduced from North America in the 19th century. They are nearly twice the weight and more aggressive than red squirrels and so out-compete them for food and territory. They have been spreading north for some years and pose a serious threat to Scotland’s native biodiversity, both directly, by driving the red squirrel towards extinction, and indirectly by damaging young broadleaf trees when they strip bark to get to the sugary sap underneath. This impedes the flow of water and nutrients to other parts of the tree, affecting size and growth form, and can lead to tree death. This impacts both native woodland regeneration and the economic viability of commercial broadleaf forestry.
Did you know
Grey squirrels are larger, live in higher densities and can consume much greater quantities of food than reds. They are also able to digest young acorns before they are ripe enough for red squirrels to eat and will pilfer the cached food supplies of reds. This means that whenever they occur together in areas where there is overlap in their preferred food sources (i.e., in mixed or broadleaf woodland), the greys will outcompete the reds for food and drey sites, leading to lower red reproductive success and survival rates, eventually resulting in localised red extinctions.