1. Squirrels breed once or twice a year and give birth to a varying number of young after three to six weeks, depending on species. The young are born naked, toothless, and blind. In most species of squirrel, only the female looks after the young, which are weaned at around six to ten weeks of age and become sexually mature at the end of their first year. Ground-dwelling species are generally social animals, often living in well-developed colonies, but the tree-dwelling species are more solitary.[5]
2. Ground and tree squirrels are typically diurnal or crepuscular,[9] while flying squirrels tend to be nocturnal—except for lactating flying squirrels and their offspring, which have a period of diurnality during the summer.[10]
