One egg is laid each day, in the morning. The average clutch has three to five eggs but as many as seven have been reported. Clutch sizes tend to be smaller for younger females and for second broods of the breeding season. The eggs are smooth and glossy and are sky blue or white in color. Because all eggs laid by a single female are the same color, the presence of an odd-colored egg in a clutch may indicate that another female has laid her egg in the nest, a practice know as egg dumping.
Females generally begin to incubate the day the last egg is laid.
The incubation period is 12 to 14 days but can be longer in the case of extreme or prolonged cold weather. Nesting Care Nestlings hatch within one or two days of each other. The female broods the nestlings for a few days. Both adults tend the young. The nestlings begin to thermoreguiate, or regulate their own body temperatures, when the are about six days old, and females decrease the amount of time they spend brooding.