The Eastern Bluebird (Sialia sialis) is a lovely little American thrush that is seen throughout the eastern half of the United States and north into Southeastern Canada. They are partial migrants, being residents in the south of their range but visiting the north only during the warmer months of the year.
You’ll often see these birds in pairs, and the fact that the males and females are pretty easy to tell apart makes observing them especially interesting. But how exactly do you tell female Eastern Bluebirds from males?
Female Eastern Bluebirds are relatively easy to identify, especially when seen together with their bright blue partners. Their gray and blue upper parts contrast clearly, with their reddish sides and white belly. Female Eastern Bluebirds also differ from their male counterparts in behavior, especially when it comes to nest site selection and construction.
Female Eastern Bluebird eating berries
Eastern Bluebirds readily use nest boxes set up in suitable areas, and watching a pair of these birds interacting around the nest can make for fascinating viewing. There's a lot that goes on behind the scenes, however, and bluebird couples aren’t necessarily the picture of wholesomeness we once thought they were.
Female Eastern Bluebirds may be easy to identify in the east of their range, but birdwatchers in the Midwest and Southwest can find it difficult to distinguish these birds from other Sialia species. The situation can be confused even further by the fact that the various species are known to hybridize.
This article covers the identification of the female Eastern Bluebird. We’ll also cover loads of interesting facts along the way to enhance your bird-watching experience the next time you spot one of these beloved American birds.
Female (left) and male (right) Eastern Bluebirds perched on a branch
The easiest way to tell the difference between male and female Eastern Bluebirds is to look at the face, crown, and nape. These areas are bright blue on male birds and grayish-blue on females. Female Eastern Bluebirds also have a whitish throat while this area is rusty on males.
These differences between male and female Eastern Bluebirds are most obvious when the two birds are seen side by side. Keep reading to learn more details about the females’ appearance.
Female Eastern Bluebird
Male Eastern Bluebird
Female Eastern Bluebirds are small to medium-sized songbirds from the thrush family (Turdidae). Their large black eyes, solid black beaks, and strong black legs, combined with their short wings and thickset body, make for a pretty robust little bird. They measure about 7 inches (12.5 cm) in length and weigh about an ounce (28 g) on average.
Female Eastern Bluebirds are blue-gray above extending from the back to the crown of the head and the sides of the face. Their wings, rump, and tail are a subdued blue color.
The sides of the neck, the breast, and the sides of the belly are a warm reddish brown color, and the throat, belly, and vent area are white. Females also have a fine white ring around their eyes.
Female Eastern Bluebird with a mealworm in her beak
Female Eastern Bluebirds are most easily confused with females of North America’s other two bluebird species. Read on to learn how to tell these female songbirds apart.
The Western Bluebird may overlap with the Eastern Bluebird in Western Texas. It’s a good thing that these two bird species do not usually occur together because they can be pretty tough to tell apart!
Look out for the following features of the Female Western Bluebirds:
Female Western Bluebird
Mountain Bluebirds occur in many of the same states as Eastern Bluebirds. The two species are closely related and even hybridize from time to time, making accurate identifications pretty tricky. Typical female Mountain Bluebirds can be identified by looking at the following features:
Female Mountain Bluebird
Female Eastern Bluebirds are generally slightly heavier than their male counterparts, although the difference is just an 8th of an ounce or less. Females may be slightly heavier than males, but their wings are often a little shorter. Differences in plumage are a much more reliable way of distinguishing females from males because these minor size differences are not visible in the field.
Female (left) and male (right) Eastern Bluebird pair perched on a branch
Observing the different behaviors of male and female Eastern Bluebirds can make watching these beautiful birds just that much more entertaining. Here are some interesting differences in the behaviors of males and females.
Male Eastern Bluebirds sing to attract a breeding female and to mark their territories.
Interestingly, the female uses a similar song when confronted with a predator, rather than when looking for a mate. She will also call when her partner has left their territory, possibly to attract him back into the area.
Female Eastern Bluebird calls are generally similar to males. Only the females use the chip call, however, a vocalization made while they are being wooed by a hopeful male.
Close up of a female Eastern Bluebird
Male and female Eastern Bluebirds show some fascinating behavioral differences during the breeding season. Continue reading to learn more.
The male selects the nest site and attracts the female by displaying with nesting materials at the entrance to the cavity. Once the female is convinced, he abandons the project, leaving the task of nest construction to his mate.
Females do not seem to mind this job too much and will often build several nests in suitable areas nearby, even though they will only use one.
Female Eastern Bluebirds can be surprisingly aggressive when it comes to nesting. These birds nest in cavities such as woodpecker holes and nest boxes, and females will fight with other females and bird species over suitable nest sites.
These fights can be intense, and some female bluebirds succumb to their injuries. Males may be even more aggressive than females, although males usually only fight with other members of their own sex.
A pair of nesting Eastern Bluebirds gathering materials to build their nests - female (left) and male (right)
Female Eastern Bluebirds occasionally lay their eggs in the nest of another female. This sneaky behavior ensures that their genes get passed on to a new generation without all the effort of incubating eggs and feeding chicks!
Other females are always on the lookout for intruders because they know to guard against this behavior.
The female Eastern Bluebird sits on the eggs alone. Incubation usually takes about two weeks, although times of 11 to 19 days have been recorded, depending on the ambient temperatures.
She remains on the eggs all through the night, although she comes and goes during the day, spending about 60% of the time on the nest. Incubating females are vulnerable to attack from predators like raccoons, particularly at night.
Both partners share the task of feeding the nestlings a diet of insects, other invertebrates, and small fruits like mulberries. They feed their young between 1.4 and 2.2 times per hour during the day, and each parent does about an equal amount of the work.
Female Eastern Bluebird at nesting box with food for the chicks
It is possible for female Eastern Bluebirds to raise their chicks without the help of the male. In some cases, however, males provide even more food than their partners.
Female Eastern Bluebirds are not very blue at all, although deep blue areas on the shoulder, primary wing feathers, and tail are visible. These birds are predominantly blue-gray above, with a reddish color on the sides and a white belly. The bill, eyes, and legs are black.
Female Eastern Bluebird with her hungry chick, begging for food
Female Eastern Bluebirds produce a variety of calls and songs. They usually vocalize for the following reasons:
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