Squirrels use their large bushy tails as a balance aid while climbing making them perhaps the most agile mammal in Ireland. The red squirrel is smaller in size and build to the grey squirrel but is more agile in the tree canopy as a result. The fore feet leave a four toed footprint while the larger hind feet have five toes and measure up to 6cm in length.
Adult male and female red squirrels are similar in size weighing up to 400 grams each but can vary in weight by up to 10 % at certain times of the year depending on the seasonal availability of food. Adults can grow up to 25cm in length with a long bushy tail equal to the length of the head and body combined. They have excellent eyesight with a wide angle of vision and a sharp focus which allows for rapid movement within the tree canopy while foraging. They are not a very vocal species but will make chattering calls and stamp or flick their tails to give a distinctive chucking sound on wood and ground surfaces. As the name suggests red squirrels have furry coats of a reddish brown with a darker tint on the back, in winter this coat is moulted to produce a warmer chocolate brown and grey colouration with the fur surrounding their ears becoming more erect in appearance during their second moult which easily distinguishes them from the grey squirrel species.