True Blue

Emily White, B.Sc. - Featherfields
2009-07-08

The bluebird, a member of the thrush family, is native to North America. There are three species – Eastern, Western, and Mountain – all of which rely on natural or artificial cavities, such as dead trees (called snags), holes in wooden fence posts, and birdhouses, to make homes.

At one time the bluebird was a common sight, prevalent throughout North America. Toward the end of the 1800’s, however, changes in land use, along with competition from other birds, began threatening the survival of the bluebird. In southern Ontario we have Eastern Bluebirds that return each spring to reside mainly in open areas – farmland, orchards, meadows and parks. They began losing this habitat when people started developing rural land and removing snags. Steel poles replaced wooden fence posts. Pesticide use reduced the food supply of bluebirds – insects, berries, and fruits.

During the 1970’s, preservationists began building and maintaining bluebird trails with birdhouses. The best locations for bluebird nest boxes are in the midst of grassy areas with a fence or tree nearby for perching. Generally, the birds require two or three acres of lawn or meadow surrounding the nest to find enough grasshoppers, crickets, caterpillars, and beetles to feed their young. Most suburban tracts are not this large, so providing a central nest site will allow the birds to range into neighbouring yards to hunt.

Face the box’s entrance hole away from the prevailing wind (southeast is ideal in southern Ontario). To maximize habitat, mount two boxes 15-20 feet apart. Bluebirds defend a good-sized territory, but Tree Swallows, who assist bluebirds in defending nests against wrens and sparrows, often accept the second box.

Nest boxes mounted on fences may be discovered by raccoons and snakes, which use fencerows as travel corridors. Boxes are safest when mounted 5-6’ high on individual poles with baffles that prevent predators from climbing.

Predator guards are devices that attach directly to the nest box, extending out from the entrance hole, and make it difficult for a predator to reach down into the nest. Some bluebird boxes come equipped with a 2” thick block of wood with a hole in the middle the same size as the entrance hole. Another option is to add a store-bought predator guard that is a plastic 3” long tube with a 1 ½” diameter and attaches onto the entrance hole of a nest box. These nest hole extensions may not be accepted by all birds, but when it is not possible to protect the box any other way - for instance, when it is mounted on a fence post - they are certainly worth a try.

Sometimes bluebirds are in your area but a female may seem reluctant to build a nest. There are a few things you can do that may encourage her. Gather dry, fine grasses or pine needles and place them in little bunches in the general area of the nest. Females will often go to these piles within minutes. Some success has also been had with placing a few strands of material in the nest hole. This may help to stimulate the female.


A birdbath may persuade bluebirds to select your yard. Like most songbirds, bluebirds prefer bathing in water that is only an inch or two deep. Place some flat stones in the bath so birds can splash around without immersing themselves. Locate your birdbath away from places cats can lurk, and keep it filled with clean water.

Bluebird populations were faltering because the birds needed nesting habitat. Now that human landlords are aware of these needs and are supplying suitable homes, bluebird numbers are increasing.

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