Birdwatchers and ornithologists noticed a decline in the number of eastern bluebirds in 1950s. The main reasons for this decline was attributed to the loss of good nesting habitat and sites, indiscriminate use of pesticides, and competition from other, more aggressive cavity nesting species.
The eastern species is comparatively smaller in size. Males have a blue back with a rusty red breast, while the lower belly is white. The females are similar, but the colors are not as bright. Young bluebirds have a speckled breast with no red coloring, and are mostly gray in appearance.
However, a tinge of blue may be visible on the wings. Bluebirds are about seven inches in length. Mountain species are slightly slimmer when compared to the other two. Males of all three species appear brighter than their female counterparts. They mainly feed on insects but also consume fruits and berries, especially in winter.
Bluebirds are basically cavity nesters and use old holes made by woodpeckers and natural cavities in large tree posts. They appear to be very fond of birdhouses, especially if it is of the right size in a warm, shaded area.
Although these houses are used primarily in the spring, autumn is also a good time to build them as bluebirds are early nesters. Also, in case of harsh winter weather, bluebirds use these houses to shield themselves from the cold winds.
It has been observed that the birds prefer the slightly smaller area of the Peterson house, but making this kind of house is comparatively difficult because of the number of angles involved. They are also more expensive when compared to the traditional birdhouses.
If you want to build a nest box, you will need a lumber piece of dimensions 1" x 6" x 6". Rough cut lumber is recommended as the birds can hang on to these better. Ensure that the entry hole is 1.5" in diameter. Galvanized nails should be used as they do not rust. Clean the house every time you anticipate a new family to take over.
They prefer nest boxes on a tree stump or wooden fence post that is not more than three to five feet high. The entry hole should face northward as this will protect the nest from excessive sun and wind.
A good management program in your locality will help insure that the bluebirds using your houses will be successful in raising their families. The decline in the population of these gentle and beautiful birds has been alarming. The good news is that the number of bluebirds being reported are increasing again.