The breeding season of the Great Tit Parus major is divided into two periods: the early and late seasons. In the early breeding population, the number of pairs varied from 45 to 152, with an average of 102±24 SD. In comparison, the late population was smaller than the early population every year and varied from 30 to 95, with an average of 54±18 SD pairs. Half of the early breeders were adult breeders from the previous year, and most of the remaining breeders were young belonging to winter flocks in previous years. The late breeding population consisted mainly of pairs that were producing their second brood that season, and repeat breeders whose first brood had failed. The proportion of adult male and adult female pairs was higher than other pairs. Most pairs were faithful, but divorce occurred every year. The population also included some pairs that did not breed and single males. The longevity was nine years in males and seven years in females.