The United Kingdom is home to squirrels, featuring two primary species commonly observed across its landscapes: the native Eurasian red squirrel and the introduced eastern grey squirrel. Both are tree-dwelling rodents, but their presence and impact on the UK’s ecosystems differ significantly.
UK’s Native Red Squirrel
The Eurasian red squirrel (Sciurus vulgaris) is the UK’s only native squirrel species, recognized for its distinctive reddish-brown fur that can vary in shade, sometimes appearing darker in winter. These agile mammals typically weigh between 100 to 350 grams, with a head and body length of up to 24 cm and a tail of up to 20 cm. Red squirrels often develop prominent ear tufts during the winter months, which may be less noticeable in summer.
Red squirrels inhabit coniferous and mixed woodlands, preferring areas where pine, larch, and spruce trees provide their primary food source of seeds. They also consume hazelnuts, tree shoots, fungi, and occasionally bird eggs. While once widespread, their UK population has declined dramatically, now estimated at around 287,000 individuals. Strongholds for red squirrels are predominantly found in Scotland, which hosts approximately 75% of the remaining population, along with isolated pockets in northern England (such as Northumberland and the Lake District), parts of Wales (like Anglesey), and specific islands. The red squirrel is classified as endangered on The Mammal Society’s Red List for Britain’s Mammals.
The Introduced Grey Squirrel
The eastern grey squirrel (Sciurus carolinensis) was introduced to the UK from North America in the 19th century, with the first recorded introduction occurring in 1876. Initially brought over as an ornamental species for stately homes and parks, around 30 separate introductions took place until 1930, when their damaging impact became recognized, and further releases were made illegal. Grey squirrels are larger than their red counterparts, typically weighing 400-650 grams and measuring 24-28.5 cm in body length with a tail of 19.5-24 cm. They generally have a silver-grey coat with brownish tinges on their face and feet and a pale underside, though some can exhibit reddish patches.
Grey squirrels are highly adaptable, thriving in a variety of habitats including deciduous woodlands, parks, and urban gardens, where they are a common sight. Their diet is broad, consisting of nuts, seeds, acorns, tree buds, and occasionally bird eggs. This species possesses several competitive advantages over red squirrels, including their larger size, broader diet, and ability to digest unripe seeds with high tannin content, such as acorns, which red squirrels cannot. Grey squirrels also carry the squirrelpox virus, which does not affect them but is typically fatal to red squirrels, causing skin lesions and lethargy, often leading to death within weeks. This disease has been a significant factor in the decline of red squirrel populations.
Distinguishing Between Species
Size is a key indicator; grey squirrels are noticeably larger and heavier, often almost double the weight of red squirrels. Red squirrels typically have a more slender body build compared to the stockier grey squirrels.
Coloration is another clue, though it can be misleading. Red squirrels generally have a vibrant reddish-brown coat, while grey squirrels are predominantly silver-grey. Some grey squirrels can display reddish-brown patches, especially on their face and legs, and red squirrels can have a greyer tinge to their fur in winter. A more reliable visual cue is ear tufts: red squirrels often grow distinct, long ear tufts in winter, which are absent in grey squirrels.
Grey squirrels spend more time foraging on the ground in urban and park settings, while red squirrels are often observed higher in trees, moving through the canopy. Red squirrels are generally more solitary, whereas grey squirrels can be more social and may be seen in groups.
Conservation and Coexistence
Conservation efforts for red squirrels are focused on protecting remaining populations and managing the spread of grey squirrels. Red squirrels are a protected species under UK law. Strategies involve managing habitats to favor red squirrels, which thrive in coniferous and mixed woodlands, and implementing targeted grey squirrel control programs. These control measures are particularly concentrated in red squirrel strongholds and at the boundaries where grey squirrel populations are expanding.
Public awareness campaigns educate people about the threats posed by grey squirrels and how to contribute to conservation. The public can assist by reporting squirrel sightings, which helps monitor populations and plan interventions. Maintaining feeder hygiene is advised to prevent disease transmission, especially the squirrelpox virus, between species. Ongoing research, including studies on gut bacteria differences, aims to better understand grey squirrel competitive advantages to inform future conservation strategies.