Goldcrests typically live from 5 years 3 months to 8 years 9 months, although the maximum recorded lifespan is 7 years and the theoretical lifespan ranges from 5 years to 7 years 1 month. The species reaches sexual maturity from 1 month 3 weeks to 1 year 1 month. Development begins with the embryo stage, during which the developing organism resides inside an egg. Following this, the nestling stage lasts from 2 weeks 2 days to 3 weeks, during which the young are fed insects by their parents while they remain in the nest. The post-fledging stage, when the young bird leaves the nest and learns to fly and forage independently, lasts from 1 to 3 months. The adult stage, a period when the bird is capable of reproduction, extends from 1 to 5 years.