Archive for Thursday, March 16, 2006

Springtime project: Make a house for Eastern bluebirds

March 16, 2006


One measure of vitality in an urban area is the number of homes erected each year. Unfortunately, this development leads to the decline of other types of dwellings. Wildlife often depends on the grass and trees that covered the land before houses took their place. However, there is one species of bird that can be encouraged to move in with new home construction - only on a smaller scale. The Eastern bluebird is often considered a harbinger of spring and can be enticed to stay with the proper shelter, environment and food. Here are the steps you can take to hang your "For Rent" sign on a newly constructed bluebird house:

Eastern bluebird populations have decreased drastically during the past four decades. By some estimates, their numbers are down by 90 percent. A major cause for this decline is a decrease in nesting sites. Bluebirds are cavity nesters and prefer to live in old tree cavities not created by themselves. The clearing of land, the use of fewer wood fence posts and removal of dead trees have eliminated most of their cavity nesting sites. However, creating an artificial home has proven effective for this "not-so-picky" nester. There are many different plans that can be used to build a bluebird house. But there are some basics that ensure a quality product that a searching pair can't pass up. Use 5/8- or 3/4-inch exterior grade plywood, or cedar. Redwood, oak and pine can be used, but redwood and oak are expensive and can split when they dry, and pine is not as durable and will last only a few years. Do not use treated lumber, lumber painted with lead paint or interior grade lumber, including OSB board. Avoid using cardboard, plastic jugs or tin cans as these provide little insulation from the summer heat.

The entrance hole should be exactly 1 1/2 inches and should be at least 7 inches from the bottom of the floor of the box. Use a screwdriver or nail to score a series of horizontal lines on the inside of the box under the hole opening. These lines will assist the fledgling young to climb the box and exit when they are ready to leave. The bottom of the box should be 4 inches square with either the corners cut off or 3/8-inch holes drilled in each corner to allow water to drain from the bottom.

The top should overhand the entrance hole by 3 inches, and do not use a perch on the front of the box as this will allow predators easy access to the goodies inside.

As with all real estate: location, location, location. Put the box 100 to 300 yards from another bluebird box as bluebirds are very territorial. Boxes are best located near the edge of the woods and can be placed around open meadows, pastures, large backyards, cemeteries, parks, old orchards and cutover woodlands. Mount the box on a metal pole or fence post 4 to 6 inches off the ground. Orient the opening away from the south wind and western rain storms. Angling the opening toward another tree or some sort of perch will assist in the overall process. Avoid attaching the box to a tree or utility pole as this may invite unwanted guests such as snakes, squirrels and ants.

Once inhabited, the pair will begin to construct a neat, cup-shaped nest made of fine grass and small roots. Then the female will lay one egg per day for four to six days. There she will incubate them for 12 to 14 days, after which time the eggs will hatch. Once the birds have been cared for in the nest for about 14 to 19 days, they will climb out and take flight to explore their newfound freedom. Adults and young alike feed on grasshoppers, flying insects, beetles and caterpillars close to the ground. As a result, do not use pesticides and leave some grassy areas to grow tall to attract such a meal.


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