The red squirrel or Eurasian red squirrel (Sciurus vulgaris) is a species of tree squirrel in the genus Sciurus common throughout Eurasia.
Mating can occur in late winter during February and March and in summer between June and July. Up to two litters a year per female are possible. Each litter usually contains three or four young although as many as six may be born. Gestation is about 38 to 39 days. The young are looked after by the mother alone and are born helpless, blind and deaf and weigh between 10 and 15 g. Their body is covered by hair at 21 days, their eyes and ears open after three to four weeks, and they develop all their teeth by 42 days. They still suckle from their mother until weaning occurs at 8 to 10 weeks.
During mating, males detect females that are in oestrus by an odor that they produce, and although there is no courtship the male will chase the female for up to an hour prior to mating. Usually multiple males will chase a single female until the dominant male, usually the largest in the group, mates with the female.
Source: en.wikipedia.org/wiki/Red_Squirrel - 07.04.2010
The Red Squirrel is resting but not hibernating during the cold season and sometimes it breaks it for eating.