During the last 60 years, bluebird numbers have decreased 90% in the eastern United States. There are five reasons for the decline:
- the widespread use of pesticides (DDT) decreases food supplies
- severe winters increase winter mortality
- changing agricultural practices with well-trimmed orchards with no cavity
trees for nest sites and on farms, almost no wood fencing with wood posts
- increasing urban sprawl and shopping malls diminishes habitat
- House Sparrows & European Starlings compete aggressively for
remaining nest sites
Finding suitable nestsites is perhaps the most severe problem the bluebird faces today. Allowing trees to mature and develop natural cavities takes too long. A much quicker solution is to provide “man-made” nest boxes. When bluebird houses are placed in good areas, bluebird populations increase rapidly.
Put bluebird houses up by the end of February in open fields, pastures, golf courses, schools, cemetaries, parks and large lawns which provide excellent bluebird habitat. Place houses 5 to 6 feet off the ground and 100 yards apart. Face houses to the south or southeast, if possible. Mount the next boxes on smooth metal pipe or conduit (3/4-1″). Do not mount boxes on trees, telephone poles, buildings or any kind of fences. Try to select places where trees, shrubs, utility wires or fences are within 25 to 100 feet of the houses. Bluebirds use these structures for perches when feeding. These perches are also helpful to your fledglings during their first flights.
If houses are located near woods and brush piles, other species, such as, chickadees, titmice, nuthatches, and wrens will use the birdhouses. These species, like the bluebird, are welcome additions to the area and should not be discouraged. These birds are also helpful in controlling insect populations. It may be possible to get a bluebird to nest in the same area by placing another house about 20 feet from the one another bird is using. Tree swallows are very compatible and make a great neighbor to the bluebird in pairing boxes.