Grey squirrels are active during the day (5); they feed on seeds, nuts, buds, insects, bird eggs (5) and fungi, depending on the time of year (3), and are well-known for their habit of hoarding food in autumn to see them through the harsh winter months (3). Seeds, cones or nuts are hidden in small scrapes scattered over the ground and buried (3). The general area is remembered, and then the cache is re-found by smell over fairly short distances (3).
Breeding takes place in December to February, and again in March to May. During this time, a number of males may follow a female when she is about to come into oestrus; during this 'following phase' the female may occasionally turn on the male and rebuff his advances by lunging at him aggressively. The day the female comes into oestrus, a number of males chase the female, making 'buzzing' noises; this is known as the 'mating chase', and the female can respond aggressively to males. Through much male-male chasing, dominant males are able to get closer to the female; when she is ready she crouches on the ground, and the first male to reach her mates with her (3). Gestation takes up to 44 days, during which time females are solitary, and nest in a 'drey' of twigs and leaves (4). If conditions are good (5), two litters are produced each year, consisting of one to eight young (5). The young are usually weaned by ten weeks (4), and reach sexual maturity at 10 to 12 months of age (5). The average lifespan is eight to nine years (5).