There was a time in the not too distant past when the Eastern Bluebird seemed doomed to extinction. Some of the favorite nesting sites of bluebirds were old wooden fence posts conveniently hollowed by time, weather, and an occasional woodpecker. All around the country as wooden fence posts were replaced with metal ones, the birds lost a treasured building site. Dead trees and limbs with cavities, also a favored nesting site, were destroyed or were gradually taken over by the starling and house sparrows, both introduced species and both much more aggressive than the bluebird.
As fewer and fewer of the beloved bluebirds were sighted each year, concerned citizens around the country decided to take matters into their own hands. Bluebird boxes started being placed in areas attractive to the little thrush who carries the sky on its back and makes our hearts glad when we hear its soft lilting warble.
Hardly a day goes by now that bluebirds are not sighted in this part of the country. They are year round residents, feeding on the many berries that are seldom ice or snow covered. When harsh weather does arrive, I supply plenty of currants (small dried raisins) and MEAL WORMS. My friends say I'm the only person they know who raises worms in her laundry room. The two food supplements are kept in the bluebird feeder year round and the amounts increased when ice and snow cover the earth. The time and cost are nothing considering the pleasure derived from having these delightful bits of nature share their life with me and allowing me to PHOTOGRAPH them.
Early in the spring here in the south, the male bluebird will start searching for a suitable nesting site and will be approved or rejected by the female. I have often found that if a nest site is suitable, a blade or two of grass will be placed in the nest as sort of a reservation. This has happened too many times to be just a coincidence.
A few days later, nest building activity begins in earnest. Both the male and female bluebird have been observed taking nesting material into the nesting cavity, whether it is a cavity in a tree, a post, or provided nesting BOX. Pine needles are a favorite material in this area. Soft dry grass is also used. The nest will be maybe a thin layer or may be built to within reach of the entrance hole.
A clutch of three to as many as eight (usually 4 to 5) sky-blue eggs, or occasionally pure white, will be layed at the rate of approximately one a day and the mother bluebird starts incubating them after the arrival of the last egg. In about two weeks, the nestlings emerge, eyes closed and featherless and hungry. About every fifteen or twenty minutes, a small insect, beetle, or ripe berry is fed to each baby from sunup to sundown.
The babies fledge (leave the nest) after approximately sixteen days. The parents continue to feed them as they learn fend for themselves. Bluebirds will raise as many as four broods, depending on how early in the spring they begin nesting and how long the summer lasts. Nestlings from an early brood have been observed helping the parents feed those in a later brood. A week or so after the fledglings have left the nest, the mother returns and starts the process all over again.
In this area of the south, whole families of bluebirds remain together all winter, feeding on berries such as dogwood and sumac. Currants (a small raisin) can be placed in the bluebird feeder along with meal worms. During the raising of the infants, trip after trip is made to the feeder is made by the parents to select choice meal worms for the little ones.
Because so few natural nesting cavities remain, bluebirds readily accept boxes made by humans. A bluebird box should be at least six inches from the bottom of the entrance hole to the floor so the babies will be out of reach from predators. The entrance hole should be 1-1/2 inches round to allow entrance by the bluebirds but will keep starlings out. Inside dimensions should be at least 4 inches square.
Occasionally I find tree limbs or small tree trunks with holes suitable for nesting. I cut them to simulate a bluebird box, more space below the hole than above. Then simply nail a floor and roof on like I would on a box, making sure the floor had sufficient drainage.
I make nesting boxes out of pine or most any kind of lumber. Cedar is good to use because it will weather well without paint. In this area, squirrels are a problem because they will chew out the entrance hole so they can fit in only to find that the house is too small for them. But by doing this, they have made the hole big enough for starlings to enter. To prevent this, I nail a piece of metal (such as a can lid with a 1-1/2 in hole cut out) over the entrance hole. Pine or other low grade lumber should be painted with a light color exterior latex paint to preserve the wood and keep the house cooler in hot weather. Never paint the inside of the box or use chemical wood preservatives.
The house should be mounted on a post or pole approximately five feet off the ground and in an open area. The hole should face AWAY from the direction in which storms arrive.This keeps the wind and rain from coming in on the babies. A fence or electrical line is good to have near for perching. The adults like a high perch for spotting insects on the ground.
I usually have three or four bluebird houses in my yard. Although Bluebirds are territorial and will not allow other bluebirds to be within the distance of about a football field in length, other desirable birds will use the boxes. Chickadees, titmice, flycatchers and others will readily accept the bluebird box. If sparrows should try to take over, either trap and relocate or eliminate them. I used to have the outlook of live and let live until the day I found a whole clutch of bluebird eggs on the ground underneath the bluebird box. The babies were close to hatching and holes had been pecked in all of the eggs. From that day on, I declared war on sparrows. This year alone, I have removed sparrow nests and eggs from one bluebird box at least fifteen times. They are persistent and should never be allowed to continue nesting activities.