In North America, breeding begins earlier in the south than in the north. Clutch size generally averages near 4 in the southern U.S., near 5 in the northern U.S. and southern Canada. In the northern U.S., most females produce 2-3 broods per year; generally clutch initiation occurs about 4-7 days after fledging of a brood, though quicker renesting sometimes occurs. Incubation averages 12 days, mostly by female. Young are tended by both parents, leave nest at an average age of 14-17 days. In various areas of North America, hatching success was 50-83%, fledging success was 53-78%, and nesting success was 31-71% (see Anderson 1994).