The three North American bluebird species, belonging to the genus Sialia, are celebrated for their vibrant plumage. Unlike many bird species, bluebirds exhibit pronounced sexual dimorphism, meaning the sexes look noticeably different. The male’s brilliant coloration is a clear signal, but the female’s appearance is more understated. Understanding the specific visual characteristics of the female bluebird requires moving past the male’s striking blue.
The Subdued Palette: Identifying the Adult Female
The adult female bluebird has a generally muted color scheme compared directly to the male, who displays vivid, deep blue plumage. Her coloration is much duller and more grayish-blue on the back and head, often described as a washed-out blue or slate-gray. This less intense coloring provides camouflage while she is on the nest.
The most noticeable difference is the breast and throat area, which is a pale brownish-gray or dusty orange-brown, contrasting with the male’s strong rusty chest. Although her body is subdued, the female retains some blue on her wings and tail feathers. This blue is less brilliant than the male’s, but it remains a key identifier, distinguishing her from purely gray-brown birds.
The female’s muted colors are an evolutionary adaptation that helps her blend into her surroundings, particularly when incubating eggs. The limited blue is often confined to the edges of the wings and the tail, while the back and mantle are dominated by gray and brown tones.
Regional Differences in Female Appearance
While the general rule of a subdued female holds true, the three species of North American bluebirds—Eastern, Western, and Mountain—each have distinct markings. The female Eastern Bluebird is characterized by a mostly grayish-brown back and breast, with the only significant blue coloring concentrated on the wings and tail feathers. Her breast coloring is a subdued orange-brown or rusty color that does not reach the intensity of the male’s.
Female Western Bluebirds are slightly more colorful than their Eastern counterparts, often displaying a trace of rust or reddish-brown (cinnamon) on their flanks or the sides of their breast. Crucially, the female Western Bluebird’s throat is typically grayish, unlike the Eastern female’s more distinctly colored throat. This species also shows blue on the upper parts, but it is duller and less extensive than the male’s.
The female Mountain Bluebird is the most distinct of the three, lacking the prominent reddish or brownish chest markings seen in the other two species. She possesses an overall pale, dusty blue-gray appearance, with the blue coloration largely limited to the wings, tail, and rump. Her breast can vary from gray to a very pale reddish-brown during certain times of the year, but her light blue-gray body is a reliable field mark.
Avoiding Misidentification
Distinguishing an adult female bluebird from other small, blue-tinged passerines or from young bluebirds requires attention to specific details. Juvenile bluebirds, regardless of sex, are often confusing because their plumage is entirely different from the adults. Juveniles are characterized by a grayish-brown body with distinct white speckles or spots across the breast and back.
These speckles are a temporary feature of youth; adult females possess uniform, unspotted plumage, making this a reliable way to differentiate them. Other blue-colored birds may also be mistaken for a female bluebird. For instance, the female Indigo Bunting is typically a plain brown bird lacking significant blue coloration. While a Blue Jay is prominently blue, its much larger size, distinct crest, and black barring make it easily distinguishable from the smaller bluebird.