Female Mountain Bluebird: Plumage, ID Pictures, and Behavior

This article covers the most relevant aspects of the female Mountain Bluebird. It goes over the female bluebird plumage, identification, and behaviors. Let’s dive in to unveil some fascinating aspects of one of America’s most beloved birds.

What does a female Mountain Bluebird look like?

The plumage coloration of the female Mountain Bluebird is variable and includes two plumage types. Female Mountain Bluebirds can be of the gray plumage type or the rufous plumage type. There is also intermediate plumages, which add to the plumage variety in females Mountain Bluebirds.

Gray plumage type: Females of the gray type have the head, back, and breast ashy gray. The folded wing (wing coverts) are bluish gray. The rump (lower back) is light blue. But this is difficult to notice as it is concealed by the folded wings when the bird is perched.

The flight feathers, (long feathers of the wing) are blue. The tail feathers (rectrices), are blue, and tend to be brighter blue than flight feathers.

Rufous type: Females of the rufous plumage type have the head, back and back gray-brown. The bread and upper belly is warm brown. The folded wing (wing coverts) are bluish gray but more saturated.
The rump (lower back) is blue. But this is difficult to notice as it is concealed by the folded wings.

The flight feathers are blue. The tail feathers are blue. Overall, the plumage of females of the rufous plumage type is more saturated than in birds of the gray plumage type.

Intermediate plumage type: Females within this group may lean towards either the gray or rufous plumage types.

In plumages of all types, the lower belly, or area around the base of the legs, and undertail coverts, are whitish. The bill and legs color are black.

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Gray Plumage Type

The gray plumage type in female Mountain bluebirds is perhaps the most distinctive and easy to identify.
Upperparts: The head is gray-brown This plumage type is more likely to have a better defined white eyering.
The lower neck and back are ashy-gray. The wing coverts on the folded wing are bluish gray, which is variable. The flight and tail feathers are blue. This can be difficult to see in a perched bird. In flight and while the bird is preening itself, the color of the wings and tail are more obvious.
Underparts: The throat is whitish. The breast and sides of the upper belly are ashy-gray grading to whitish towards the center and lower belly.

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Rufous Plumage Type

The rufous plumage type in female Mountain bluebirds is perhaps the most confusing because it resembles females of other bluebirds.
Upperparts: The sides of the neck, throat and forehead are rufous or warm-brown. It appears not to have a well-developed eyering.
The crown and back are gray. The wing coverts on the folded wing are bluish gray, which is variable. The flight and tail feathers are blue. Females in freshly-molted plumage show white fringes on the wing and tail feathers.
Underparts: The throat and breast are rufous, which grade to . whitish towards the center and lower belly. The color saturation of the breast fades as the plumage gets older.

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Intermediate Plumage Type

The intermediate plumage type in female Mountain bluebirds falls between the gray and rufous plumage types.
Upperparts: The head is gray with a tinge of on the forehead and cheeks. The lower neck and back are bluish-gray. The wing coverts on the folded wing are bluish gray, which is variable. The flight and tail feathers are blue. The tone and saturation of wings and tail feather is variable. This individual has a well saturated blue in the wing and tail feathers.
Underparts: The throat and breast are whitish-brown grading to whitish towards the center and lower belly. The change in tones in the underparts may be difficult to discern in the field

Do female Mountain Bluebirds change color in the winter?

No, female Mountain Bluebirds do not change color in the winter. Unlike many other birds that have distinct winter and summer plumages, female Mountain Bluebirds, maintain the same plumage throughout the year.

They do, however, undergo an annual molt during the end of summer and fall, where they replace their feathers. The fresh plumage in adult birds appears brighter than the old plumage, but the colors and patterns remain the same.
While female Mountain Bluebirds show subtle changes in plumage during their annual cycle and transition from juvenile to adult plumage, these changes are difficult to observe in the field.

It is worth noting that the reddish tinge on the breast and sides of the neck in birds of the rufous plumage type is conspicuous during the autumn and early spring. Overall, brighter plumages are observed during the winter as a result of freshly molted feathers.

Variation in the female Mountain Bluebird plumage is similar throughout the species’ range 

Field observations and formal studies suggest consistent plumage characteristics in female Mountain Bluebirds across their entire range. Female plumages in the northern regions of their range exhibit similar traits to those found in the southernmost areas of their range.

While overall plumage types remain consistent, individual variation exists. The saturation of the plumage varies with the age of the feathers changing from bright colors and pale fringes in freshly-molted plumages to more muted colors in old plumages.

Size of a female Mountain Bluebird

Female Mountain Bluebirds closely resemble males in terms of length, weight, and wingspan. Overall, there are no significant size differences between Mountain Bluebird sexes. Hence, distinguishing between female and male Mountain Bluebirds based solely on size is challenging.

The following table provides the ranges and average measurements for length, weight, and wingspan of female Mountain Bluebirds. Since measurements are so similar the table below uses measurements from both sexes to obtain the range and average.

Measurements of a female Mountain Bluebird

	Average	Range
Length	16.7 cm 6.6 in	15.5–18 cm (6.1 – 7.1 in)
Weight	29 gr 1.1 oz	23-35 grams (0.84 -1.35 oz)
Wingspan	32 cm 12.7 in	10.8 -14.6 in (28-36 cm)

I found that in terms of weight and length, a female Mountain Bluebird is about the size of familiar birds such as the House Sparrow (Passer domesticus), Cedar Waxwing (Bombycilla cedrorum), and Chimney Swift (Chaetura pelagica).

What does a juvenile female Mountain Bluebird look like? 

Young female Mountain Bluebirds are brownish drab with less saturated tones of blue in the wings and tail than juvenile males. Young females can be observed during the months of May through August.

Upperpasts: Head and back are brown. Sometimes have faint white streaks on the back. The wing coverts, are a dark brown with brownish or drab buffy-brown edges. Their wings and tail are light greenish-blue edges with lighter gray. 

Underparts: The breast is brown with pale spots grading to a lighter and unspotted belly. 

Young female Mountain Bluebirds reach sexual maturity as early as 8 to 11 months after fledging and are capable of breeding by the following spring and summer after leaving the nest.

No age-related color variation after the second year

The distinctive gray plumage of juvenile female Mountain Bluebirds born in the spring and summer is replaced with pre-adult or formative plumage by the end of the Fall.

The formative plumage is similar to the definitive adult plumage. However, first-year females, are generally duller and more grayish than older individuals.

After the second year, there is no age-related plumage variation. Mountain Bluebirds can be bluer or grayer due to individual variation and environmental factors.

How can you distinguish a female Mountain Bluebird from other similar bluebird species?

A female Mountain Bluebird can be confused with the female Eastern Bluebird and Western Bluebird.
Female Mountain Bluebirds, particularly those with rufous plumage type (see above), can resemble the less colorful female Eastern Bluebirds and Western Bluebirds.

• Size and proportions: Compared to the Western Bluebird and Eastern Bluebird, the Mountain Bluebird is slightly larger in size. It has a longer, thinner bill, a more upright posture, and relatively longer legs and wings.
• Wing coverts: The Mountain Bluebird differs from its counterparts by having less prominent light edges on its wing coverts.
• Neck coloration: Unlike the Eastern Bluebird, the Mountain Bluebird lacks rufous coloration on the sides of its neck.
• Head and back coloration: In contrast to the Western Bluebird, the Mountain Bluebird has more consistent coloration on its head, nape, and back, without a grayish head and brownish back.

How to identify a female Mountain Bluebird in the field?

Female Mountain Bluebirds share similarities with other female bluebirds. The best approach to identify them is by using the five tenets of bird identification: range, size & shape, color pattern, behavior, and habitat.

• Range: Mountain Bluebirds are primarily found in Western North America, overlapping with Eastern Bluebirds only in certain areas and seasons. This means you mainly need to compare female Mountain Bluebirds with female Western Bluebirds.
• Size and Shape: Female Mountain Bluebirds have a slender body, long wings, and a moderately thin bill. They also have an upright posture, distinguishing them from other female bluebirds.
• Plumage pattern: The key distinction between female Mountain Bluebirds and Western Bluebirds lies in the head and breast coloration. Female Western Bluebirds have an orange-brown chest and a gray head, creating a sharp contrast. In contrast, female Mountain Bluebirds exhibit smoother color transitions between the head and breast, without a noticeable contrast. Female Eastern Bluebirds display orange on the cheeks and sides of the neck.
• Behavior and Habitat: All bluebirds share similar behaviors and prefer open habitats with scattered trees and short vegetation on the ground. However, Mountain Bluebirds tend to favor more open and higher elevation habitats compared to Western Bluebirds, which are often found in lower elevation areas.

Songs and calls produced by a female Mountain Bluebird

The female Mountain Bluebirds give soft and melodic calls, which has been described as a dee-weer. This call is also given by the male and it is the most common vocalization given by the Mountain Bluebird.

– Perch Calls

– Flight Calls

This call can be given as a single call or repeated consecutively with multiple variations, depending on the context. The call is short lasting approximately 0.2 seconds.

Females also produce short flight calls, which are given nearly exclusively when the bird is in the air.

What are the typical behaviors of female Mountain Bluebirds?

Female Mountain Bluebirds have a stereotyped behavior when foraging for food, which is what they do most of the time. They use a combination of aerial hunting, ground foraging, and perching waiting behaviors to search for and capture insects on the ground and in the air.

Perch and Watch: They perch on elevated spots like fence posts or tree branches to observe their surroundings for potential prey. From these perches, they can spot insects or other small animals moving nearby. When they identify a target, they launch into flight or swoop down to the ground to capture it.

Aerial Hunting: They are skilled at hunting insects in the air. They actively fly and scan their surroundings for flying insects like beetles, grasshoppers, and flies. With their excellent maneuverability and agility, they can quickly change direction to pursue their prey. When they spot an insect in the air, they swoop down swiftly to catch it.

Ground Foraging: Mountain Bluebirds also search for food on the ground. They hop or walk on the ground, making short bursts of movement as they look for small invertebrates such as spiders, ants, and caterpillars. They may also pick insects from vegetation or the ground’s surface.

Nesting Behavior and Reproductive Role of Female Mountain Bluebirds

Female Mountain Bluebirds are actively involved in nest site selection, nest construction, egg laying, incubation, parental care, and nest defense, all of which contribute to the successful reproduction and survival of their offspring. Specific nesting behavior and reproductive roles:

Nest site selection: They actively choose suitable nesting sites, such cavities in trees, old woodpecker holes, or man-made nest boxes as nesting sites.

Nest construction: The female takes the lead in constructing the nest, gathering materials like grasses, feathers, and plant fibers to create a soft lining.

Egg laying: Females lay a clutch of 4 to 7 light blue or pale blue eggs, ensuring appropriate intervals between each egg.

Incubation: The female primarily incubates the eggs for about 12 to 14 days, regulating temperature and humidity to support embryo development.

Parental care: Both the female and male Mountain Bluebird participate in caring for the nestlings, taking turns feeding them a diet mainly consisting of insects and small invertebrates. Both parents take care of the young in the nest for 18-21 days until the babies fledge.

Nest defense: Female Mountain Bluebirds are protective of their nest and offspring, displaying aggression towards threats and actively defending the nest through vocalizations and aggressive displays.

Conclusions:

This article has provided an exploration of the female Mountain Bluebird, shedding light on its plumage variations, identification techniques, and behaviors. By unraveling these fascinating aspects, we hope to foster a greater appreciation for this remarkable bird and inspire further exploration of the diverse avian world around us.

Photo Credits:

The photographic material used in this article was made available on various websites. Many thanks to Wendy Miller, Rick From Alabama, Mick Thompson, Doug Greenberg, DFoulder, U.S. Fish and Wildlife Service.

Voices:

Most recordings were made by Paul Marvin (Xeno-canto https://xeno-canto.org/contributor/RFTXRYBVBX)

References and Sources:

• eBird. (https://ebird.org/)
• Birds of the World (2022). Edited by S. M. Billerman, B. K. Keeney, P. G. Rodewald, and T. S. Schulenberg. Cornell Laboratory of Ornithology, Ithaca, NY, USA. https://birdsoftheworld.org/bow/home
• Sibley, David, 2000, The Sibley Guide to Birds.