The vibrant blue plumage and gentle song of the bluebird make it a highly sought-after resident for many yards, signaling a healthy and thriving ecosystem. Bluebirds are insectivores, providing natural pest control by feeding on common garden insects like grasshoppers, caterpillars, and beetles. Attracting these stunning birds, which include the Eastern, Western, and Mountain species, requires a proactive approach addressing their specific needs for shelter, food, and a safe habitat. Providing a welcoming environment for these cavity-nesting birds involves careful attention to housing, diet, and landscape design.
Setting Up the Ideal Nest Box
Providing a purpose-built nest box is essential, as bluebirds are secondary cavity nesters and cannot excavate their own homes. A correct entrance hole size is paramount for attracting bluebirds while excluding larger, non-native competitors like the European Starling. For the Eastern Bluebird, the entrance should be a circular hole measuring 1.5 inches in diameter; Western and Mountain Bluebirds require a 1 9/16-inch opening. The floor dimensions inside the box should be approximately 4 by 4 inches or 5 by 5 inches.
The structure should be built from untreated wood, such as cedar or cypress, which provides insulation and durability. The box must be mounted on a smooth metal pole rather than a tree or fence post to deter climbing predators. A height of four to seven feet above the ground is recommended for optimal placement. Boxes should feature ventilation holes near the top and drainage holes in the floor. The roof should overhang the entrance by at least one to two inches to protect the interior from rain and direct sunlight.
Proper orientation and access are important considerations. The entrance hole should ideally face away from the prevailing winds to prevent rain from entering the cavity. A good design includes a side or front panel that opens easily for monitoring nesting activity and cleaning after each brood fledges. This regular maintenance helps ensure the box remains a safe and sanitary option.
Supplying Specialized Food and Water
Bluebirds rarely consume traditional birdseed mixes, relying instead on a diet primarily composed of insects and wild fruits. Supplemental feeding should focus on high-protein options, with live or dried mealworms being the most effective attractant. Mealworms can be offered in a specialized feeder with smooth, high sides to prevent the larvae from crawling out, or in a shallow, open-tray feeder.
Dried mealworms should be soaked in warm water for about 10 minutes before serving, making them more appealing and easier to consume. Specialized suet cakes, particularly those with an insect-based formulation, are also readily accepted, especially during colder months when natural insects are scarce. These suet offerings should be placed in feeders that allow the birds to perch and feed upright, as bluebirds are not comfortable hanging upside down.
Providing a reliable water source is essential. Bluebirds prefer a shallow birdbath, with the water depth no more than two or three inches. A dripper or mister feature can be effective at attracting them, as the sound and movement of dripping water signal a fresh source. The birdbath must be cleaned frequently to prevent the growth of algae and bacteria, ensuring the water remains clean and safe.
Creating a Bluebird-Friendly Landscape
Bluebird habitat requires open, grassy areas that facilitate their preferred hunting method: perching and swooping down to catch ground insects. They thrive in environments like pastures, large lawns, and lightly wooded parklands, preferring these over dense forests. Scattered trees and shrubs provide necessary elevated perches for surveillance and shelter, but too many trees can attract unwanted nest competitors.
Leaving up a few dead branches or installing low wires can encourage hunting by providing perching spots. Eliminating or drastically reducing the use of chemical pesticides is important because bluebirds rely heavily on a plentiful insect population. Insecticides directly reduce the birds’ primary food source, especially during nesting season.
Landscaping with native, berry-producing plants offers a dependable food source when insects are less available. Shrubs and trees produce fleshy fruits that bluebirds readily consume, including:
- Flowering dogwood
- Holly
- Sumac
- Hackberry
Protecting Bluebirds from Predators and Competition
Protection from predators and aggressive competitors is a priority for nesting success. A smooth, stovepipe-style baffle should be installed on the mounting pole to deter climbing mammals like raccoons, squirrels, and snakes. The baffle should be at least eight inches in diameter and twenty-four inches long, and mounted so it can wobble slightly, which prevents climbers from gaining a foothold.
The non-native House Sparrow is a major threat, often aggressively taking over nest sites and killing adult bluebirds and their young. While the 1.5-inch entrance hole excludes European Starlings, House Sparrows can easily fit through it. Active management is necessary to control House Sparrows, including the immediate removal of their nests and eggs.
Regular monitoring of the box allows for the timely identification of any threats. Cleaning the box after each successful brood is necessary to prepare the site for the next nesting cycle.