Introduction and Identification
On
March 30, 1927, the eastern
bluebird was officially designated
the Missouri state bird by an act of the
Missouri Legislature because it was "common
in Missouri" and "a symbol of happiness."
This was an appropriate selection in every
respect. Referring to its pleasing color, naturalist
Henry David Thoreau once wrote that "it carries the sky on
its back." Add
to that its delightful song, non-aggressive manner
and beneficial food habits, and you have a
truly appealing bird. And, people can even
become involved with this state bird by building
bird houses. Most important for a state
symbol, bluebirds are fitting for Missouri.
They seem to favor the rolling Missouri
countryside where they may be seen flitting
about from fencepost to fencepost on any
bright spring morning. For those who witness
the flash of blue and hear their "cheer-cheeryup"
song in such a setting, the phrase "bluebird
of happiness" takes on a special meaning.
Identification
Male
Strikingly blue on the back, wings and tail; rusty breast, white belly.
Female
Blue-gray on back, wings and tail; otherwise similar to male.
Young Bluebird
White flecks on blue upper parts; dark speckles on white breast. Young males more brilliantly blue than young females.
Habitat & Foods
Habitat
In summer,
bluebirds
frequent rural grasslands
where there
are scattered trees for
perching and nesting.
They also live where
there are large lawns
such as at cemeteries,
golf courses and parks.
Historically, they were associated with savannas, which are open
woodlands with an understory of grasses and wildflowers. A necessary
component of bluebird nesting habitat is an appropriately
sized nesting cavity. Before settlement, these were woodpecker
holes or decayed branches. Today, bluebirds also readily nest in
manmade nest boxes.
Foods
Bluebirds are voracious
predators of
grasshoppers and crickets, which they
locate from a perch and pounce on, pinning
them to the ground with their bills.
They also eat beetles, bugs, caterpillars, spiders
and flying insects, the latter often captured during
short flights. Those that winter in Missouri move to where food is
available, consuming foods such as rose hips and cedar, poison ivy
and sumac berries. They also find dormant insects and, on warm
winter days and along shorelines, even active insects.
Population Trends
The number of bluebirds in
Missouri has varied over time
in response to many factors.
The Breeding Bird Survey
indicates high numbers
in recent years. People who
believe bluebirds are becoming
rare may have moved from the
country to the city during their
lives or witnessed their local habitat
become brushy. Still, bluebirds are not
without problems. The removal of dead trees
and branches for firewood or neatness continues
to eliminate existing or potential nest cavities. If it were
not for the many Missourians who maintain nesting boxes,
bluebirds would probably be far worse off.
Range and Cycle
Range
The Annual Cycle
Bluebirds arrive at nesting sites in February and March. The male selects a nest site and offers the female food. The female accepts the site by bringing nest material. She builds the nest. Second and even third nestings can occur through the summer until as late as August. Nest failure and re-nesting can alter the latter part of this schedule.
- January-February: Wintering flocks begin to break up
- February: Pairs arrive on the breeding territories; begin territorial singing
- March: First nests constructed First eggs laid
- April-May: First brood fledges
- May: Second nesting initiated
- June: Second brood fledges
- July:Rarely, third nesting initiated
- August: Third Brood fledges
- September-October: Bluebirds in northern Missouri begin migration
- September-December: Family groupings gradually join larger wandering flocks from mid-September through December
Nesting Behavior
Eggs are laid one per day over the number of days necessary to produce the clutch. Incubation, done entirely by the female, begins with the last egg laid so that all hatch on the same day and the young fledge synchronously.
Both parents feed the young but the female alone broods them. New nestlings are fed small, soft insects, such as caterpillars. As nestlings grow, the parents bring them larger insects and spiders and feed them more frequently—as often as every five minutes by the end of the nesting period. Droppings are produced in a fecal sac and carried well away by parents to thwart predator detection of the nest site.
When 15 to 18 days of age, the stubby-tailed, speckled young exit the cavity and fly to a nearby perch. They stay close together at night. The parents stop feeding them at seven to ten days after fledging.
Nest Boxes
Bluebirds readily accept appropriately placed manmade nest boxes, perhaps because of a shortage of natural nesting cavities. Nest boxes have the added advantage of excluding starlings if the entrance is 1½" in diameter. Boxes can increase the local bluebird population and offer many hours of enjoyment.
When to place nest boxes
Place new boxes and clean out and refurbish existing boxes by March 1.
Where to place nest boxes
Place boxes in open, grassy areas with perching sites. Meadows, pastures, savannas, cemeteries or yards that are not too heavily shaded are ideal. It is best if the grass is short. Fence lines, power lines, scattered trees or nearby woods provide good perches. Boxes placed in forests, inner cities, shaded yards, cultivated fields or areas with only tall grass will probably be unsuccessful.
How to situate nest boxes
For best results, mount the box on a lone post. Posts can be fitted with a 24" long metal sleeve to discourage climbing predators. Posts in fence rows can become overgrown with brush, enabling black rat snakes and mice to enter the box. Tree trunks are often too shaded or easily climbed by squirrels and snakes.
- Height: 4 to 5 feet. Bluebirds nest at almost any height, but this height is convenient for checking.
- Space: 300 feet apart. This accommodates the bluebird's sizeable territory. Boxes placed closer might be used at the same time if not in sight.
House Design
The top may be mounted on a hinge, or a 1/2" dowel may be substituted for the hold-down strip for the roof. Either bevel the corners on the bottom or drill four 1/4" holes for drainage. Pine or other easily worked wood is recommended. Painting is not necessary. If painted, use light gray or tan paint.
Monitoring
Once a bluebird pair initiates nesting, you can open the box and check the eggs or young until they reach 13 days of age. After that, leave the young alone so that they are not frightened and do not leave the nest too early.
Maintenance
Clean out old nest material as soon as the young have fledged. This will help keep future nests well below the entrance hole and safer from predators. Discard the nest material at a distance so that it is not reused—handy nest material may encourage sparrows to nest in the box.
Establish a Bluebird Trail
A bluebird trail is a series of boxes spaced along a route where they can be periodically monitored and maintained.
Check the houses every week to ten days for the following problems:
- House sparrows: Not only are house sparrows more aggressive than bluebirds when competing for nest boxes, they will occasionally kill the young bluebirds by pecking their heads. House sparrows are not protected by state or federal law, and they should be continually discouraged by removing nests and eggs as soon as they appear. Their easily recognized nests are messy structures of grasses, feathers and assorted litter. The eggs are white and speckled with brown. If house sparrow problems continue, move boxes to at least ¼ mile away from any buildings.
- Starlings: A 1-1/2" entrance hole will exclude starlings. Wood-peckers or squirrels, however, will sometimes enlarge holes, enabling starlings to enter. If this happens, nail a board with the proper-sized hole over the front of the box. Starlings are not protected by law.
- Wrens: Punctured eggs or a box filled with sticks and thorns are evidence of the house wren. Sometimes wrens even kill young and adult bluebirds by pecking their heads. Competition from wrens probably indicates that the box is too near brushy cover. House wrens are protected by law.
- Other Bird Competitors: Boxes used by chickadees, tufted titmice, nuthatches or flying squirrels are probably in areas that are too wooded for bluebirds. Go ahead and allow these native species to use the box.
- Blow flies: Both fly eggs and larvae will sometimes become established in a bluebird nest. The larvae will suck blood from young bluebirds. If this occurs, lift up the nest with your fingers and gently tap it. The larvae will fall out of the nest and can be removed from the bottom of the box.
If you are building nest boxes, please make certain that they will be looked after once in place. Boxes that are not looked after may instead benefit bluebird competitors such as house sparrows and starlings. There is evidence that neglected boxes may do more harm to bluebirds than if there were no boxes at all.
Feeding Bluebirds, Winter Roost Boxes, & Other Blue Songbirds
Feeding Bluebirds
Bluebirds do not eat seeds, so rarely visit ordinary bird feeders. To see bluebirds up close, attract them with special foods. Some Missourians make cakes of yellow corn meal glued together with cooled bacon drippings or similar cooking grease with bits of fruit or raisins throughout. Berries collected in summer can be dried or frozen and provided during cold weather. If the reason for feeding is to promote bluebird survival, it is better to plant dogwoods, sumacs, cedars, hawthorns or similar plants that provide natural winter foods.
Fresh water is an attractant, especially in winter.
Winter Roost Boxes
Some bluebird enthusiasts have advocated winter roost boxes to protect bluebirds on cold winter nights. Missouri Department of Conservation research has revealed that standard nest boxes provide the best shelter of any manmade structures. Occasionally, people find dead bluebirds in boxes; the birds may have been unable to forage because of snow or ice cover and would have starved regardless. Of course, natural cavities provide the best protection.
Several days of sub-freezing cold and snow or ice cover can cause mass mortality among bluebirds. It took nearly a decade for Missouri's population to recover from the hard winters of the late 1970s.
Other Blue Songbirds
Indigo Bunting, male
The eastern bluebird has two relatives that live in western North America—the western bluebird (Sialia mexicana) and the mountain bluebird (Sialia currucoides). The latter, an all-blue species, very rarely wanders into Missouri. The most likely solid blue birds to be seen in Missouri are the male indigo bunting—a small, deep-blue bird—and its larger, look-alike cousin, the blue grosbeak.
For more information:
- The Bluebird Book: The Complete Guide to Attracting Bluebirds by Donald and Lillian Stokes. 191. Little, Brown and Co. Paperback. 96pp.
- Missouri Bluebird Society: www.missouribluebird.org
- North American Bluebird Society: www.nabluebirdsociety.org
Bluebird Nest Box Monitoring Form
If you are interested in tracking the success of your bluebird boxes, you may wish to use this form.
| Box No. | Date(s) of Egg Laying | Total Eggs | Total Hatched | Total that Fly | Comments (Predation, etc.) |
