What bluebirds expect in a home

Like owls and woodpeckers, eastern bluebirds prefer nesting in cavities of dead oaks and pines. More and more of these natural nesting habitats have been lost through the years, however, as woodlands and open fields have been developed.

Bluebirds initially adapted by nesting in rotting wooden fence posts, but they have been replaced with more durable metal poles. As a result, bluebird populations waned until conservationists and birders began setting out bluebird houses or nest boxes. This eco-friendly activity continues to prove successful when the following tips are kept in mind.

The male is the "real estate expert" among eastern bluebirds and is finicky about the home he selects. He and his mate may take up residence in a man-made bird house - but only if it is constructed and installed according to precise requirements. An unpainted or light-colored nesting box is best, because a dark-colored roof can overheat the house on hot summer days and potentially damage any eggs inside.

An entry hole measuring no more than 1.5 inches helps keep out unwanted intruders, as does a smooth metal post instead of a wooden support. A predator guard on the support pole, such as a sheet-metal collar or cone-shaped baffle, also is necessary to prevent raids by snakes, raccoons and egg-eating predators.

A side or front-opening box allows easy monitoring of the occupants. It also helps with the cleaning process, which is especially important this time of year. Because broods have matured and most adult birds have left their nests, a thorough cleaning is required before winter. The birdhouse should be emptied and brushed clean, but no sprays or cleaners of any kind should be used inside it.

A bluebird nesting box can be installed now as an optional winter habitat and in preparation for next spring's mating season. The best location is an open pasture, field or park preferably near a wooded area. Ideally, the nest box should be mounted about 5 to 7 feet off the ground and at least 50 feet from brush or shrubs, because that is wren territory.

"Bluebird numbers have gone down due to encroaching habitats and loss of habitat in our region, so it's good to see people putting up boxes to give the birds a place to raise a family," said Linda Chaney, a volunteer who monitors the bluebird trail at Lewis Ginter Botanical Garden.

"It's also fun to watch the bluebirds check out the box and to see the first births in the spring."

Tom Brinda is assistant executive director for horticulture and education and Lynn Kirk is public relations writer at Lewis Ginter Botanical Garden.