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Eastern Bluebird

Sialia sialis ORDER: PASSERIFORMES FAMILY: TURDIDAE

IUCN Conservation Status: Least Concern

Eastern Bluebird Photo

Most of the country drives during an eastern North American summer will turn up a few Eastern Bluebirds sitting on telephone wires or perched atop a nest box, calling out in a short, wavering voice or abruptly dropping to the ground after an insect. Marvelous birds to capture in your binoculars, male Eastern Bluebirds are a brilliant royal blue on the back and head, and warm red-brown on the breast. Blue tinges in the wings and tail give the grayer females an elegant look.

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At a GlanceHelp

Measurements
Both Sexes
Length
6.3–8.3 in
16–21 cm
Wingspan
9.8–12.6 in
25–32 cm
Weight
1–1.1 oz
28–32 g
Relative Size
About two-thirds the size of an American Robin
Other Names
  • Merlebleu de l'Est (French)
  • Azulejo garganta canela (Spanish)

Cool Facts

  • The male Eastern Bluebird displays at his nest cavity to attract a female. He brings nest material to the hole, goes in and out, and waves his wings while perched above it. That is pretty much his contribution to nest building; only the female Eastern Bluebird builds the nest and incubates the eggs.
  • Eastern Bluebirds typically have more than one successful brood per year. Young produced in early nests usually leave their parents in summer, but young from later nests frequently stay with their parents over the winter.
  • Eastern Bluebirds occur across eastern North America and south as far as Nicaragua. Birds that live farther north and in the west of the range tend to lay more eggs than eastern and southern birds.
  • Eastern Bluebirds eat mostly insects, wild fruit and berries. Occasionally, Eastern Bluebirds have also been observed capturing and eating larger prey items such as shrews, salamanders, snakes, lizards and tree frogs.
  • The oldest recorded Eastern Bluebird was 10 years 5 months old.

Habitat


Grassland

Eastern Bluebirds live in open country around trees, but with little understory and sparse ground cover. Original habitats probably included open, frequently burned pine savannas, beaver ponds, mature but open woods, and forest openings. Today, they’re most common along pastures, agricultural fields, suburban parks, backyards, and golf courses.

Food


Insects

Insects caught on the ground are a bluebird’s main food for much of the year. Major prey include caterpillars, beetles crickets, grasshoppers, and spiders. In fall and winter, bluebirds eat large amounts of fruit including mistletoe, sumac, blueberries, black cherry, tupelo, currants, wild holly, dogwood berries, hackberries, honeysuckle, bay, pokeweed, and juniper berries. Rarely, Eastern Bluebirds have been recorded eating salamanders, shrews, snakes, lizards, and tree frogs.

Nesting

Nesting Facts
Clutch Size
2–7 eggs
Number of Broods
1-3 broods
Egg Length
0.7–0.9 in
1.8–2.4 cm
Egg Width
0.6–0.7 in
1.5–1.9 cm
Incubation Period
11–19 days
Nestling Period
17–21 days
Egg Description
Pale blue or, rarely, white.
Condition at Hatching
Naked except for sparse tufts of dingy gray down, eyes closed, clumsy.
Nest Description

After a male Eastern Bluebird has attracted a female to his nest site (by carrying material in and out of the hole, perching, and fluttering his wings), the female does all the nest building. She makes the nest by loosely weaving together grasses and pine needles, then lining it with fine grasses and occasionally horse hair or turkey feathers. Nest boxes in some places are so common that a single territory may contain several suitable holes. Females often build nests in each available hole, but typically only use one of these. Bluebirds may use the same nest for multiple broods.

Nest Placement

Cavity

Eastern Bluebirds put their nests in natural cavities or in nest boxes or other artificial refuges. Among available natural cavities, bluebirds typically select old woodpecker holes in dead pine or oak trees, up to 50 feet off the ground. Older bluebirds are more likely than younger ones to nest in a nest box, although individual birds often switch their preferences between nesting attempts. When given the choice in one study, bluebirds seemed to prefer snugger nest boxes (4 inches square instead of 6 inches square on the bottom) with slightly larger entrance holes (1.75 inch rather than 1.4 inch diameter).

Behavior


Ground Forager

This small, brightly colored thrush typically perches on wires and fence posts overlooking open fields. The birds forage by fluttering to the ground to grab an insect, or occasionally by catching an insect in midair. Bluebirds can sight their tiny prey items from 60 feet or more away. They fly fairly low to the ground, and with a fast but irregular pattern to their wingbeats. Males vying over territories chase each other at high speed, sometimes grappling with their feet, pulling at feathers with their beaks, and hitting with their wings. The boxes and tree cavities where bluebirds nest are a hot commodity among birds that require holes for nesting, and male bluebirds will attack other species they deem a threat, including House Sparrows, European Starlings, Tree Swallows, Great Crested Flycatchers, Carolina Chickadees, and Brown-headed Nuthatches, as well as non-cavity nesters such as robins, Blue Jays, mockingbirds, and cowbirds. Males attract females to the nest with a display in which he carries bits of nesting material into and out of the nest. Once a female enters the nest hole with him, the pair bond is typically established and often remains intact for several seasons (although studies suggest that around one in every four or five eggs involves a parent from outside the pair).

Conservation

status via IUCN

Least Concern

Eastern Bluebird populations increased by almost 2 percent per year between 1966 and 2010, according to the North American Breeding Bird Survey. Partners in Flight estimates the global breeding population at 22 million, with 86 percent spending part of the year in the U.S., 22 percent in Mexico, and 1 percent breeding in Canada. They rate a 7 out of 20 on the Continental Concern Score and they are not on the 2012 Watch List. Eastern Bluebird populations fell in the early twentieth century as aggressive introduced species such as European Starlings and House Sparrows made available nest holes increasingly difficult for bluebirds to hold on to. In the 1960s and 1970s establishment of bluebird trails and other nest box campaigns alleviated much of this competition, especially after people began using nest boxes designed to keep out the larger European Starling. Eastern Bluebird numbers have been recovering since.

Credits

Range Map Help

Eastern Bluebird Range Map
View dynamic map of eBird sightings

Migration

Resident to medium-distance migrant. Bluebirds leave breeding grounds in the north of their range to winter in the southeastern U.S. or Mexico. Populations in the northern part of their range are entirely migratory, spending winters in the southeastern United States or Mexico. Some fly as far as 2,000 miles between western Manitoba and Texas. Eastern Bluebirds from the southeastern U.S. may move short distances south or simply remain on their breeding territories all year.

Backyard Tips

Eastern Bluebirds don’t often visit feeders, but they are a great prospect for nest boxes if you have the space to put one up in your yard, and if your yard isn’t too hemmed in by trees or houses.

Find This Bird

You can find Eastern Bluebirds in open country with patchy vegetation and large trees or nest boxes. Meadows, old fields, and golf courses are good places. Bluebirds typically sit in the open on power lines or along fences, with an alert, vertical posture. When they drop to the ground after an insect, they make a show of it, with fluttering wings and a fairly slow approach, followed by a quick return to the perch.

Get Involved

Set up a nest box for bluebirds and report nesting activity to NestWatch

View and sort images of nesting bluebirds online with CamClickr to help scientists archive data from our NestCams

Report your Eastern Bluebird sightings to eBird

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Rhythm and Bluebirds: New devices track temperatures and incubation rhythms at the nest

Incubation Matters A new angle on why birds in warmer climes lay fewer eggs (BirdScope, Summer 2003)

Bluebirds Put Their Eggs into More than One Basket Renesting attempts reveal latitudinal trends in multiple broods (BirdScope, Spring 2004)