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Recently, I attended an interpretive program about birds at one of our state park nature centers. I listened closely as the interpreter told us ways we can help birds. What she said about the Eastern bluebird was especially interesting. She told us that in the spring, bluebirds begin looking for cavities for a suitable nesting site in which to lay their pale blue eggs.
She also said that if nesting cavities occurred naturally, that was great. If not, we could imitate nature by building and erecting artificial cavities for the bluebirds. Then she said something amazing. She told us that one of the best times to build a bluebird box is during either fall or winter. This allows the wood to season for a few months so it will not have such a strong smell.
Many other kinds of animals use cavities for nesting, resting and escape cover—squirrels, bats, raccoons, opossums and even mice.
While you might not want to attract these mammals, cavity structures can also be made to attract specific species of birds. It comes down to box size, hole dimension, setting, spacing between other bird boxes and height above ground. These qualities are equally important and will serve either to attract or detract birds.
I had a lot of questions, so I did some reading on my own to find out more about bluebirds.
After finding some books at the library and online, I discovered that bluebirds don’t like other bluebirds to live too close by. Bluebird boxes need to be spaced at least 150 to 200 feet apart or squabbles will develop between neighboring bluebirds.
Bluebirds prefer laying their eggs in an open setting as opposed to one that is wooded or brushy. They will even stop nesting if the area around their surroundings changes from a pasture-like setting to a more brushy area.
I remember the interpreter told us that precautions need to be taken to discourage cats, raccoons and especially two kinds of exotic birds—the house sparrow and the European starling—from settling near bluebird houses. That precaution was echoed in all the information I read about bluebirds.
She told us that the entrance-hole size for Eastern bluebirds is critical. It must be 1½ inches in diameter and should have a starling guard. That’s simply another piece of 1-inch thick wood containing the same size hole, nailed over the entrance. This creates a short tunnel through which the bluebird can easily pass. This guard not only prevents the starling from entering the box but also from sticking its head and long beak into the box to puncture the eggs or kill the bluebird nestlings. Unfortunately, a starling guard is not effective against cats, raccoons or snakes.
House sparrows can be discouraged by repeatedly removing their nesting material from the artificial bluebird box, so it’s best if you use a bluebird box with a hinged lid. If a house sparrow attempts to occupy the box, just leave the lid open, which discourages the sparrow, but not the bluebird. After the bluebird has established its nest, close the lid and the bluebird can usually handle things from that point.
If you think that building a bluebird house is too technical for you, why not plant a flowering dogwood to help provide a future fall and winter food source for these lovely birds, or make an origami bluebird or bookmark?
To find out more about interpretive naturalist programs go to: interpretiveservices.IN.gov
If you would like more information about bluebirds, go to nabluebirdsociety.org and click on “Bluebird Facts” or check out books at your local library.