Clutch size is usually 4-5. Incubation lasts 13-17 days (less often 11-19 days), mainly or totally (e.g., in Europe) by female. Often 2 broods, except in far north. Young are tended by both adults, fledge at 18-23 days, stay together and are fed by parents for about a week. Females first breed at 1 year, a few males remain unpaired until 2 years old. Adults often have same mate in successive years (Shields 1984). Juveniles may help feed young of second brood.