Facts about Eastern Bluebirds
Eastern bluebirds live in most of the United States east of the Rocky Mountains, and in parts of Southern Canada. There are also native populations of eastern bluebirds living in Mexico and Central America.
Eastern bluebirds eat mostly insects, and they tend to catch them on the ground. Spiders, grasshoppers, beetles and crickets are all favorite foods for them. During the winter when insects are hard or impossible to find, they’ll eat a wide range of fruits and seeds. Juniper berries, blueberries, sumac, mistletoe, and more are all on the menu.
Eastern bluebirds that survive to adulthood can live for 6-10 years. That’s unusually long for a wild bird to live, but most bluebirds do not survive their first year of life.
Bluebirds don’t typically mate for life, although it’s not uncommon for a breeding pair to spend more than one breeding season together. During the breeding season, they are monogamous, meaning that they form breeding pairs that work together to raise their chicks. Sometimes, the same two adults will breed for more than one season, but there’s no guarantee that this will happen.
Females will never turn bright blue, instead staying a dull blue-gray for their whole lives. Males will begin to develop bright blue feathers when they are around 13-14 days old, but it may be several days after that before they begin to show adult coloration over their whole body.
Eastern Bluebirds are small, and have trouble creating their own nests. They really prefer to find old nests made by other species and reuse them, rather than building one. Old woodpecker holes are favorite nesting sites, and they prefer for their nests to be near open fields and meadows, and often like to nest high off the ground.
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Male bluebirds have bright blue plumage on their wings and backs, while females are a duller, blue-gray color. This is quite common in songbirds; males use bright colors to attract females, while the females tend to have duller colors because it makes them harder for predators to see while they’re sitting on their eggs.
Yes and no. In most of their range, Eastern Bluebirds don’t migrate. However, there are large areas where they do. In the northernmost areas of their range in the United States, Eastern Bluebirds are present during the breeding season only, and in large portions of Texas, New Mexico, and northern Mexico are wintering grounds for these migrating bluebirds. In the Southeastern US, central Mexico and Central America they do no migrate.
Because Eastern Bluebirds prefer to find nesting sites made by other birds, they will readily take to birdhouses. They will to nest in tight, snug spaces, so smaller birdhouses are more likely to attract them. In some places people have built “bluebird trails”, areas with large numbers of nesting boxes for bluebirds to create ideal bird watching conditions.
Once they’ve mated and built their nest, a female bluebird will lay between 3 and 5 eggs. The female will incubate them while the male brings her food.
It takes about 2 months for eastern bluebirds to become fully independent. After about 22 days the chicks will be fledged, meaning they will have lost their downy feathers and grown adult feathers. That’s when they begin to learn how to fly, but it takes a while longer for them to learn all the skills they need to survive on their own.
Once she lays her eggs a female eastern bluebird will incubate them for two weeks, though sometimes they’ll hatch after 12 days.
They might use the same nest for multiple broods, but they don’t always. In fact, it’s not uncommon for a female to build several nests in one breeding season, and only use one of them. It’s also possible that they will reuse other bluebird’s nesting sites. So, if you put up a nesting box, you may have a different breeding pair using it each year.
Here are the seven subspecies of Eastern Bluebirds that are currently recognized:
Sialia sialis sialis is the most common one in the USbemudensis in Bermudanidificans in central Mexicofulva in the southwestern US and Mexicoguatamalae in southern Mexico in Guatemalameridionalis in El Salvador, Honduras, and Nicaraguacaribaea in Honduras and NicaraguaAn eastern bluebirds song is very distinctive. They make a call that sounds like “chur lee” or “chir we”. Many birdwatchers describe it as sounding like they’re singing the words “truly” or “purity”.
At one time populations were dangerously low. Invasive species like the house sparrow and the European starling were competing for the same nesting sites and making it difficult for bluebirds to breed. Construction of nesting boxes has helped a lot, and the Eastern Bluebird is no longer threatened or endangered.
Bluebirds are very social, and their flocks can number anywhere from a dozen to over a hundred birds. However, they don’t always live in flocks. During the breeding months is when you’ll typically see Bluebirds alone or in pairs, in the fall and winter they’ll be in flocks.
Despite their tendency to gather in large flocks, bluebirds are highly territorial. During their breeding season the males, in particular, will protect their nesting sights even before they’ve found a female to mate with. During the winter, all adult bluebirds will defend their favorite feeding and foraging areas.
Bluebirds will often lay eggs twice in the same breeding season. It’s not uncommon, when this happens, for the female to lay her second clutch of eggs while the male is still caring for the chicks from the first clutch.
Eastern bluebird eggs are usually blue, though a small percentage may be white. While they can be a range of different colors, each female’s eggs are all the same color.
