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Eastern
Bluebird male
(photo by Beth Donald)
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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
At a Glance
Habitat
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Food
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Nesting
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Behavior
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Conservation
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Grassland
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Insects
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Cavity
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Ground Forager
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Measurements
Both Sexes
Length
6.38.3
in
1621
cm
Wingspan
9.812.6
in
2532
cm
Weight
11.1
oz
2832
g
Relative Size
About two-thirds
the size of an American
Robin
Other Names
- Merlebleu de l'Est (French)
- Azulejo garganta canela (Spanish)
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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.
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, theyre most common
along pastures, agricultural fields, suburban parks, backyards,
and golf courses.
Insects caught on the ground are a bluebirds 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 Facts
Clutch Size
27 eggs
Number of Broods
1-3 broods
Egg Length
0.70.9
in
1.82.4
cm
Egg Width
0.60.7
in
1.51.9
cm
Incubation Period
1119
days
Nestling Period
1721
days
Egg Description
Pale blue
or, rarely, white.
Condition at Hatching
Naked except
for sparse tufts of dingy gray
down, eyes closed, clumsy.
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Nesting
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.
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).
Eastern Bluebird Nest Image 1
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Four
in the box
My backyard bluebird Mama II laid her fourth egg on 06 July.
Since she's gone a couple of days without laying another this
my be her completed clutch. Her first brood died from heatstroke
just a couple of days before they would have fledged.
(photo by Lindell Dillon).
Read more about the bluebirds on the red dirt hill at bluebirddiary.wordpress.com/
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Newly-hatched
bluebirds
The two newly-hatched Eastern Bluebirds in my backyard nestbox.
I always feel a little guilty about cheeping to make them
think Mama is there with a bug. But, they always open their
mouths and give me a good pose.
(photo by Lindell Dillon).
Read more about my bluebirds at bluebirddiary.wordpress.com/
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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
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Least Concern
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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.
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