Discover the Only Two Squirrel Species in the United Kingdom and Where They Are Most Commonly Seen

The United Kingdom is home to just two squirrel species: the Eurasian red squirrel (Sciurus vulgaris) and the eastern grey squirrel (Sciurus carolinensis). Both species share similar life histories, including being arboreal and omnivorous and breeding twice a year. Both species are also active year-round, although less so during the winter. However, while the former species was once widespread across U.K. forests, the latter species is now far more commonly seen across much of the country. Read on to find out why.

The Eurasian Red Squirrel: The Native Species

The Eurasian red squirrel is the U.K.’s only native squirrel species, with a record going back to the end of the last ice age. Red squirrels can live in coniferous, deciduous, and mixed woodlands. While they aren’t picky about the exact type of forest, however, they still need sufficient amounts of undisturbed habitat to thrive. As it turns out, they have been less adaptable to human development than their gray squirrel cousins.

The Eastern Gray Squirrel: An American Import

The eastern gray squirrel is a familiar sight to many across the eastern United States. This is because that is actually its native range. However, these squirrels were imported to the U.K. in the 1870s as an ornamental species to populate garden estates. Unfortunately, from these introductions, many escaped into the wild. They were then able to easily adapt to their adopted home’s lowland forests and reproduced quickly. And, just like in the U.S., they have also been able to readily adapt to human-altered landscapes. Gray squirrels are now seen across much of the U.K. in parks and gardens, suburban yards, and even urban areas with at least some trees around for food and shelter.

From Red to Gray Across the U.K.

The introduction of the gray squirrel turned out to be a disaster for the native red squirrel. As gray squirrel populations have increased and expanded, so too have red squirrel populations decreased and contracted. As a result, the Eurasian red squirrel is currently classified as Endangered in the U.K., while the eastern gray squirrel is classified as Invasive.

Current estimates place the U.K.’s gray squirrel population at around 2.7 million. In contrast, the red squirrel population has plummeted to just 287,000. Furthermore, 75% of that remaining population lives in Scotland, the species’ last remaining stronghold outside of Ireland on the British Isles. Smaller red squirrel populations also persist in other northern areas, on islands, and in remote pockets elsewhere in the country.

As seen on the map above, there are areas where the two populations still overlap. However, whenever the two species meet, the gray squirrel eventually wins out. This is because the gray squirrels have a number of advantages over their red squirrel cousins. First off, they are bigger. Second, they are more tolerant of human development. Third, they have a higher tolerance to tannins. This means they can eat nuts before they’re ripe, while red squirrels must wait. And fourth and most alarming, gray squirrels carry a virus known as squirrelpox that is transmissible to red squirrels. While the gray squirrel carriers are immune, it has proven fatal to red squirrels.

How To Tell Reds and Grays Apart – Don’t Just Count on Color!

While it may seem at first that you could simply tell the red and gray squirrel species apart by their respective fur colors, don’t let their common names fool you. While it is true that red squirrels are usually red and gray squirrels are usually gray, both grayish red squirrels and reddish gray squirrels are not uncommon. Furthermore, either species can have coat colors that can vary from white, brown, red, gray, and black. This is because both species get their fur colors from melanin pigments — just like all other mammals, including us humans!

While color may not in and of itself be a reliable identification tool, other differences can be used to help tell native red squirrels and non-native gray squirrels apart:

Ear Tufts

Most notably, only red squirrels have those cute ear tufts. However, these are shed down in the summer. Gray squirrels, on the other hand, are tuftless year-round.

Tails

Red squirrels also have a fairly uniform tail color. In contrast, gray squirrel tails generally look more multicolored.

Overall Size and Weight

Lastly, red squirrels are also markedly lighter and smaller than their gray squirrel cousins. While red squirrels weigh in at only 9 – 12 ounces, gray squirrels are plumper at 14 – 21 ounces. Likewise, red squirrels only grow to a length of 7.5 – 9 inches plus a tail length of 6 to 8 inches, while gray squirrels can grow to a length of 9.1 – 11.8 inches plus a tail length of 7.5 – 9.8 inches.

Summary of Discover the Only Two Squirrel Species in the United Kingdom and Where They Are Most Commonly Seen