Eastern Bluebirds

Bluebirds are one of North America’s favorite birds, and one of the many songbirds that have declining populations.  They have been affected by both urbanization of North America, and the introduction of Starlings and Sparrows to our country.  They are members of the thrush family feeding on mostly insects but occasionally are found eating berries when insects are not available.

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Bluebirds are not capable of creating their own cavities for dwelling, but instead must find cavities to live in. They rely on old woodpecker holes or rotting trees, but will also take up residency in a manmade house. However, they tend to be more particular than most birds about how their house is designed and where it is located. Bluebirds may overwinter here, but they actively begin house hunting in February and March, signaling better weather ahead.  Bluebird houses should be mounted on poles or fence posts as they provide a little more protection from predators vs. utility poles and trees.  An Eastern Bluebird prefers a house with a floor size of 4” x 4”, a height of 8-12”, the entrance hole should be about 6 – 10” above the floor and the diameter of the entrance hole should be 1 ½” (this diameter is very important to prevent starlings gaining access).  Starlings and House Sparrows are aggressive birds who will attack and destroy bluebirds and their eggs and young in order to claim their nesting environment.  Sparrows can be kept away by adding a second house either back to back or within 5 feet of the original bluebird house.  This will often lead to each species of bird nesting at peace within their own house.  Multiple bluebird houses should be spaces 100 – 300 yards apart when creating a bluebird trail, as they are territorial birds and do not want to nest too closely.  A 3” roof overhang provides shade while a 5” overhang prevents predators such as cats and raccoons from being able to reach inside.  The house should have ventilation and drainage holes. Do not purchase a house with a perch as bluebirds do not perch and a perch will invite sparrows.  Face your bluebird house away from prevailing wind to reduce the rain from entering and being blown in. A nearby tree or shrub 100 ft. away from the entrance hole will also provide the young with a place to fly to when they first leave the nest, and safety from the elements and predators.

Bluebirds are insect eaters.  Worms, caterpillars, spiders, grasshoppers and crickets make up their main diet making them ground foragers.  You will find Eastern Bluebirds perched on wires, posts, and low branches in open country, scanning the ground for prey.  They feed by dropping to the ground onto insects or in the fall and winter, by perching on fruiting trees and shrubs plucking the berries and fruit. You can attract bluebirds to your windowsills by putting out mealworms or by putting mealworms and food with dried berries into a platform feeder. 

Male bluebirds are a brilliant royal blue on the back and head, with a warm red-brown coloring on the breast.  Females are grayer having blue tinges in their wings and tail.  The male bluebird attracts a female to his nest site by carrying nest material in and out of the hole, perching and fluttering his wings.  After he has attracted her to the site she then completes the nest building by loosely weaving together grasses, pine needles, horse hair or larger feathers.  She will produce 2-3 broods per year.  Once the young have left the nest (approx. 21 days) consider cleaning out the house so she can rebuild and lay more eggs.  Consider leaving your bluebird house up all year as they will use the boxes a winter roosts once the mating season in over.