- Lifespan
- 8–10 years in the wild; up to 20 years in captivity
- Size & Weight
- 25–30 cm body length; 200–500 g (typically 350–500 g)
- Habitat
- Deciduous and mixed woodlands, parks, gardens, and urban areas with scattered trees throughout the UK.
- UK Distribution
- Widespread resident across England, Wales, and southern Scotland; absent from northern Scotland and most of Ireland. Established as a non-native invasive species since the 1870s.
- Diet
- Primarily tree seeds, nuts (acorns, beechnuts, hazelnuts), bark, buds, fungi, and tree fruits; also raids bird feeders and occasionally eats insects and bird eggs.
- Predators
- Raptors (sparrowhawks, buzzards), foxes, domestic cats, pine martens, and occasionally stoats; juvenile squirrels vulnerable to corvids and other predators.
- Mating Season
- December to January (winter), and June to July (summer); two breeding seasons per year.
- Breeding
- Gestation period approximately 43–45 days; typically 3–4 kits per litter; two litters possible per year (spring and summer). Kits weaned at 7–10 weeks.
- Behaviour
- Highly agile and arboreal, spending most time in tree canopies. Solitary and territorial; communicate via tail signals, chattering calls, and scent-marking. Active year-round but less visible in winter; cache large quantities of nuts in autumn for winter survival.