House Hunting: What a Bluebird Looks For in a Home

Abstract

In this science project, I attempted to answer the question, "What are the elements of a bluebird's habitat?" In response, I monitored bluebird boxes for one season (spring through summer) at Wye Island Natural Resource Management Area. Approximately 50 bluebird boxes exist in various areas on the island. While monitoring the bluebird boxes, I looked for the presence of a bluebird nest, eggs, and bluebird young. Occasionally, there would be a nest of another specie of bird, such as a house sparrow, an enemy of the bluebird. I destroyed these nests. At the end of the season, I measured bluebird box height from the ground, direction each faced, and distance of each box from a field, tree, forest, water, power lines, and a road. I obtained data of previous seasons from the Wye Island resident ranger, Ranger Dave Davis. I sorted all of my data into spreadsheets and graphs. From this, I determined that the key elements of an attractive bluebird habitat were water and open fields.

Problem

Investigation: What are the elements of a bluebird's habitat?

Background Information

The eastern bluebird (sialia sialis Linnaeus) is a small blue bird with a light brown color on its breast. Its normal height ranges from 5-1/4 to 7 inches when it is an adult.

The eastern bluebird eggs are pale blue and sometimes white. The female bluebird mostly lays four to five eggs, but sometimes they can lay as little as three or as many as seven eggs. The female eastern bluebird performs most of the incubation for her soon-to-be young. Generally, this period lasts about 12 to 16 days.

When the egg hatches, the bluebird young are born. At this stage in their life, they cannot see. Within four to five days, they grow some feathers and can see. They then learn to fly by flexing their muscles and bones in their wings. Generally, the young fledge fifteen to eighteen days after birth.

The eastern bluebird's adult diet consists of insects, especially grasshoppers, crickets, katydids, beetles, earthworms, spiders, millipedes, centipedes, sow bugs, and snails. The adult also eats fruits from dogwoods, hawthorn, and wild grape in warm weather months, and sumac and hackberry seeds in winter months. Also, adult eastern bluebirds digest fruits, such as blackberries, bayberries, honeysuckle, Virginia creeper, red cedar, and pokeberries. The young eastern bluebirds' diet includes small tender insects from their hatching and larger insects as they mature.

In the spring and summer, these bluebirds live east of the Rocky Mountains, southern Canada to the states bordering the Gulf of Mexico. They can also be found in the southeast, from Arizona to Nicaragua. In the winter, the eastern bluebird is found in southern New England, west to New Mexico and south to Mexico.

Their nest is often found in a woodpecker excavated cavity, in a loose cup of dry grass, weed stems, pine needles, twigs, and sometimes with hair or feathers. Eastern bluebirds usually nest low to the ground, about two to twenty feet. Their nests are found on farmlands, orchards, open woodlands, and sparse trees on mountain slopes. According to the Northern Prairie Research Center, eastern bluebirds prefer a complex of open, low-growing grassy fields, either mowed or growing freely. The bluebird also prefers widely scattered trees, berry-producing shrubs and vines, and snags. They perch from trees, shrubs, utility wires, telephone poles, or fence posts.