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.
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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, theyre most common along pastures,
agricultural fields, suburban parks, backyards, and golf courses.
Food
Insects
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
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
Least Concern
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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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)
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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