Carolina and black-capped chickadees will use a birdhouse or, as they are sometimes called, a nesting box. You can buy one or build it yourself. The opening for the nest box should be from 1 1/8 to 1 1/4 inches in diameter to keep out sparrows. This size opening will also permit wrens and nuthatches to live there. These birds do not need a perch on their birdhouse, helping to keep sparrows away. Mount the box on a post or tree in a sunny place in or near a wooded area, from 7 to 10 feet of the ground. Chickadees will not reuse an old nest. If you have not been able to clean out the house from the previous year, be prepared for entertainment in the spring when a couple cleans house. They fling all the old nest materials from former tenants out of the hole with much vigor and enthusiasm. This is important to prevent disease and insect problems where new babies will nest.
In the northern portion of their range, chickadees nest from the beginning of May to the beginning of July. Farther south they nest from the middle of April to the middle of June. Both sexes work equally hard in nest building, using bark, moss, grass and feathers. You can help by putting out nesting materials in early spring. They produce six to eight eggs per clutch, raising one or two broods per year. Females incubate the eggs for 12 days and, while males help in raising the young, they do not stick around for more than one year. Their life span is 5 to 12 years.