The Western Bluebird (Sialia mexicana) is a small songbird found in western North America. The colorful plumage of the male Western Bluebird is well-known, with its vivid blue back and wings contrasting with an orange throat and chest. However, the female Western Bluebird has a more subdued appearance that can make her harder to identify. This article will provide a detailed overview of the key physical features of the female Western Bluebird to help with identification.
Size and shape
The female Western Bluebird is a relatively small songbird, measuring around 6.3-7.5 inches in length and weighing approximately 0.9 ounces on average. Her body is slender and rounded, with a full chest and a medium-length tail. The wings are short and rounded compared to other songbirds. The bill of the female bluebird is short, straight, and black. The legs and feet are also black.
Overall, the female has a graceful, compact body shape well-suited for perching and frequent flight. Her small size allows her to easily maneuver through dense thickets and bushes when foraging. When perched, the female Western Bluebird often cocks her tail upwards at an angle.
Plumage coloration
While not as vibrantly colored as the males, female Western Bluebirds do have distinctive plumage markings:
Head
The head of the female is a grayish-blue color, slightly muted compared to the bright azure blue of the male. The forehead, lores, crown, and nape all share this blue-gray coloring. It fades to a paler gray color on the cheeks, chin, and throat. Females lack the reddish-orange throat patch found on males.
Back
The back and upper tail coverts of female bluebirds are a muted blue-gray color. This pale blue is darker on the back and wings, compared to the light powder blue hue of the rump.
Chest and belly
The underparts of the female Western Bluebird are pale grayish-white to off-white in color. This contrasts with the bright orange-rufous chest and flanks seen on the male. The female’s chest is a plain, pale creamy white.
Wings
Females share the same blue-gray wing feathers as males, though in a paler, subdued shade. The flight feathers and wing coverts are edged with this pale blue color. The greater coverts form a faint light blue wingbar on the closed wing.
Tail
Like the wings, the female’s tail feathers are pale blue-gray. The outer retrices are edged in this washed out blue color. When fanned, the tail shows an alternating pattern of light and dark bands.
Identifying markings
In addition to her muted blue-gray and pale white coloring, the female Western Bluebird has some key identifying markings:
– Dark lores – The area between the eye and bill is a dusky gray color. This creates a noticeable dark patch separating the pale blue crown from the gray cheek.
– Faint eye ring – A thin pale whitish eye ring surrounds the eyes. This can be hard to see at a distance.
– Indistinct wingbars – The pale blue greater coverts form faint, indistinct wingbars on the closed wing. These help differentiate female bluebirds from sparrows.
– White undertail coverts – The small feathers under the base of the tail are bright white, contrasting with the blue-gray uppertail coverts. This white undertail is visible during flight.
– Dark tail spots – When spread, the pale blue-gray tail shows a faint banding pattern of darker gray spots near the end. This helps distinguish the female’s tail from the male’s solid orange tail.
Similar species
The female Western Bluebird shares the same small thrush family body type as Eastern and Mountain Bluebirds. However, the muted coloration of Western Bluebird females sets them apart from the brighter blue and rusty orange Eastern and Mountain Bluebird females.
The female Western Bluebird is most likely to be confused with other plain grayish-blue songbirds. The white undertail coverts help distinguish her from similar Western Scrub-jays. She can be differentiated from Western Tanagers by her smaller size, paler bill, and lack of wingbars. Her faint eye ring and wings bars help separate her from sparrows.
Juvenile birds
Young Western Bluebirds have plumage patterns distinct from adult females:
– Brownish gray overall color
– Faint spotting on the chest
– Pinkish bill with a dark tip
– Dark eye line
These juvenile features are lost as the birds molt into adult female plumage by around one year of age. Males take several years to acquire their full vibrant blue coloring.
Seasonal and regional variations
The female Western Bluebird’s plumage remains relatively consistent year-round. However, some small regional and seasonal differences exist:
– Winter birds appear duskier overall, with buffy scalloping on the underparts.
– Southwestern birds may have a browner gray back.
– Alaskan females have been described as nearly uniform powder blue above.
– Faded breeding plumage in late summer can make some females appear nearly white below.
Despite these minor variations, the core elements of the female’s plumage remain stable across most of her western range.
Role of female plumage
The more subdued plumage of female bluebirds likely serves an important evolutionary purpose. By blending in with the surroundings, the brooding females can remain camouflaged while incubating eggs. The neutral colors also allow the females to avoid attracting predators to the nest. Males take on the bolder, showier colors to capture the attention of potential mates.
Conclusion
While not as brightly colored as the male, the female Western Bluebird has a refined, understated beauty in her pale blue-gray and white plumage. A practiced birder can recognize the distinctive shape, markings, and flight profile of a female Western Bluebird. Her muted colors play an important role in keeping nests and young safe. With an understanding of her key identification features, observers can appreciate spotting Western Bluebird females across the western states and provinces.