Western Bluebird Guide (Sialia Mexicana)

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Reina loves watching birds and learning new ways to identify them. When she started her own lawncare company, she fell in love with our feathered friends. Currently, she is learning how to identify them from their song! She loves to share her tips, tricks, and product recommendations here on Birding Insider; you can get the most out of your birding hobby!

The Short & Tweet

An estimated 7.1 million Western Bluebirds live in scattered forests, brush deserts, and streamside groves across the western United States and central Mexico. Males and females differ in color, with males donning their namesake blue plumage and females appearing muted with a gray-buff and pale orange chest.

These social birds feed in flocks as they hunt for insects and mate in monogamous pairs. Western Bluebirds work together when it comes to raising young and will help nearby parents with their round-the-clock duties. While the species does not currently face endangerment, they have rapidly adapted to living in open areas as deforestation threatens their preferred forest habitat.

Taxonomy

William John Swainson formally recognized the Western Bluebird in 1832. Swainson was an English ornithologist, malacologist, conchologist, entomologist, and artist. Some say his love of nature was as strong as his love of being an “-ologist.” All jokes aside, we owe a lot of excellent research to Swainson, who gave the Western Bluebird its binomial name, Sialia mexicana.

There are now six recognized subspecies of Western Bluebirds:

S. m. occidentalis – discovered in 1837, their range includes southwest Canada to northern Baja California.
S. m. bairdi – discovered in 1894, their range includes the western U.S. to northwestern Mexico.
S. m. jacoti – discovered in 1991, their range includes south-central U.S. and northeast Mexico.
S. m. amabilis – discovered in 1939, their range includes north-central Mexico
S. m. nelsoni – discovered in 1991, their range includes central Mexico
S. m. mexicana – discovered in1832, their range includes south-central Mexico

How to Identify a Western Bluebird

Size & Shape

Western Bluebirds are small birds that are a little larger than a sparrow. Often described as stocky, they have thin bills and short straight tails. Both sexes are about six to seven inches long, with a wingspan of 11 to 13 inches.

Color

Males, females, and juveniles all differ in color from one another. Males have cobalt blue feathers on their heads, necks, wings, and tails. Their chest and backs are a rusty orange with a buffy white belly. Females appear mostly gray with touches of blue throughout their wings and tails and a light orange wash on their breasts. Their throats and underbellies are light grays.

Juveniles are gray-brown with white streaking on their heads and backs. Their blue wings and tail are subtle and have a white eye ring. Their breasts have a light rust color that is mixed with white.

The Difference Between Eastern, Western, and Mountain Bluebirds

In some parts of Texas and around the Rocky Mountains, there are a few areas of overlap between Eastern Bluebirds and Western Bluebirds. These two species of birds look very similar and even breed in some cases. You’ll be equipped to decipher the difference should you ponder which bird is gracing you with their presence!

The easiest way to differentiate between Eastern and Western Bluebirds is to look at their chins. Eastern Bluebirds have blue bodies with rusted orange throats, chins, and breasts. Western Bluebirds have the same color pattern but don a more vibrant blue which extends under their beak across their chin and throat.

Mountain Bluebirds live within a similar range to the Western Bluebird, but their coloration is distinctively different, so you will likely not mix up the two. Just in case you do, remember that Mountain Bluebirds do not have orange breasts and have less bold, dusty blue feathers.

Where Does a Western Bluebird Live: Habitat

These cheery and social birds prefer to be in open canopy spaces like the edges of coniferous and deciduous woodlands. Other preferable habitats include burned areas with suitable foraging and perching locations, wooded riparian regions, grasslands, and farmlands.

Unlike the Eastern Bluebird, the Western Bluebird does not like open meadows. This tip may help identify which bluebird you’ve sighted if you’re in their overlap range.

Distribution

Western Bluebirds, as their name suggests, live throughout the western United States. Their range also extends into Mexico towards Baja California and southwestern Canada.

In the United States, look for them in northwest Montana, Idaho, northeast and southeast Washington, Oregon, California, western Nevada, southern Wyoming, Colorado, east and south Utah, northwest and southeast Arizona, New Mexico, and west Texas.

Western Bluebird Diet and Feeding

The majority of a Western Bluebird’s diet is composed of various insects. Favored insects commonly include beetles, spiders, grasshoppers, crickets, and caterpillars. This watchful bird will sit atop a perch, whether a branch, fencepost, or utility pole, and wait for insects to pass by. Once spotted, they will dive to the ground to catch the meal.

As the season’s change and insects become less plentiful, the Western Bluebird must seek other food sources. Plant material and fruits like juniper berries and mistletoe berries are the bulk of their diets in the winter.

Water from running sources like rivers and streams is perfect for drinking and bathing, but they will visit bird bath’s when their options are limited.

Mealworms and suet are more likely to attract Western Bluebirds to backyard feeders than traditional birdseed. Keep scrolling to learn how to attract bluebirds to your yard best.

Western Bluebird Breeding

Western Bluebirds’ breeding practices are fascinating because they are part of only eight percent of bird species that practice cooperative breeding. Examples of other cooperative breeders include the Azure-winged Magpie and the Australian Mudnester.

Although Western Bluebirds form monogamous mating pairs, they help other parents raise their young, leading to lower adult mortality rates and small clutch sizes. Scientists also believe that cooperative breeding results from breeding in environments with limited resources.

Sometimes fledglings from the previous brood will stick around to help their parents and nearby pairs raise another brood. This is referred to as “helping.”

Western Bluebird Nesting

Selection

Migratory Western Bluebirds will begin to arrive at destinations with warmer temperatures from February to mid-May. Both sexes will begin to scout out a suitable breeding territory. These birds are cavity nesters, so competition for nesting sites can be fierce. Since bluebirds cannot excavate a nest themselves, they must rely on other species, such as woodpeckers, to do their hard work. Naturally occurring cavities in trees will also be used.

Once selected, males will show females their chosen nesting site and may even go one step further and collect some nesting materials. Ultimately, the final verdict is determined by the female. If she likes the site, the pair may enter the cavity together.

Construction

When a pair is formed, nest construction can begin. This becomes the primary responsibility of the female. Over the course of two weeks, she will collect nesting materials from the ground, such as moss, grass, bark, hair, feathers, and leaves.

These materials are loosely woven together, saving the softer grasses and moss for the interior cup. The nest construction takes the female about two weeks but is expedited when a second brood is expected.

Western Bluebird Eggs

Egg laying begins over the course of five to seven days, from mid-March to early May. Females usually lay one or two clutches throughout the mating season, with each clutch ranging between three to eight eggs. Five pale blue eggs are typical.

Incubation

The two weeks following egg laying are entirely devoted to the incubation process. Females are the sole incubators but may come and go at various times throughout the day.

Hatching

Western Bluebird — Friendly western male bluebird, California

After lots of TLC from the mama bird, the eggs hatch in the early morning. Eggs can hatch within 30 minutes of each other or up to 1 day apart. Egg shells are removed from the nest and sometimes eaten by mom and dad. Yum, nutrients!

Development

Upon hatching, the birds are altricial, and both parents take on the task of rearing the young. Hunting for food and cleaning the nest are the two most significant responsibilities. After five to seven days, the chicks can regulate their own body temperatures. By day eight, their eyes begin to open, feathers grow, and nestlings can use their feet to hold onto things. They are halfway through the growing process come day 10. Gender display isn’t apparent until day 13 or 14 when feathers fill in more consistently.

Fledging & Dispersal

As nestlings reach 21 days old, they will work up the nerve to fledge from the nest. Often the smallest bird, or runt, will fledge a day later than others. They will call their parents for food for the next three to five days as they learn the necessary foraging skills to take care of themselves. After becoming independent, fledglings may choose to stay nearby and help their parents raise a second brood.

Broods

Mated pairs will attempt to have a second brood shortly after their first brood has fledged. In some cases, the female Western Bluebird will begin laying eggs while the male stays behind and continues to take care of the first brood. Whether or not a pair attempts a second brood depends on the temperatures, food availability, and nesting availability. Nesting boxes and cavities from the first brood are reused if the first brood has fledged.

Western Bluebird Communication

After only 14 days of life, Western Bluebird younglings can begin to communicate. Granted, they only know how to demand more food, but their ability to produce more complex calls will form as they age.

Bluebirds use calls to locate each other that sound like “kew” and “che-check.” This is especially useful for mates who may have gotten separated. Calls are also used to establish and defend territory. Males chatter as females builds the pair’s nest to let other birds know the site has become occupied. A loud squawking call is produced when a male invades the territory of another male or female.

Western Bluebird Conservation Status

The global breeding population of Western Bluebirds is 7.1 million, according to Partners in Flight. They are rated 9 out of 20 on the Continental Concern Score, which means they are of low conservation concern.

Invasive and forceful birds like the European Starling and House Sparrows have negatively affected the health of several cavity-nesting species, including the Western Bluebird.

Other concerns that threaten the well-being of the Western Bluebird species are deforestation due to the logging industry and a lack of suitable habitats due to grazing and agriculture. Leaving dead trees and branches in their naturally occurring area can provide bluebirds and other cavity nesters with a potential home.

Western Bluebird Predators

While it may not sound too frightening to a human, the top predators threatening Western Bluebirds are chipmunks and squirrels. Yes, the adorable furry-tailed rodents. Other threatening predators include deer mice.

These rodents invade nests, attack chicks, and claim the nest as their own personal crash pad. Male Western Bluebirds are always on guard to defend their home and keep chicks safe. When a chipmunk, squirrel, or mouse approaches, the vigilant bluebird will grab the leg of the intruder and cause them to fall. With this advantage, the bluebird uses its beak to peck the intruder until it flees. They will also snap their beak in threatening situations, which makes a clicking sound.

The following species are known to raid bluebird nests:

Grey-necked Chipmunks
Townsend’s Chipmunks
Yellow-pine Chipmunks
Douglas’s Squirrels
Red Squirrels
Tufted-ear Squirrels
Deer Mice

Western Bluebird Lifespan

There is insufficient research available on the average lifespan of a Western Bluebird. The oldest known Western Bluebird was a male banded in California in 2001. He lived eight years and eight months. Way to go, little buddy!

How to Attract Western Bluebirds to Your Backyard

While the focus of this article has been on the beautifully vibrant Western Bluebird, most of the below tips are suitable for attracting Eastern Bluebirds as well.

Once you’ve mastered the art of attracting bluebirds to your yard, you’ll wonder why you didn’t try sooner. They sing sweet songs and are likely to raise young right under your nose if you provide the right conditions (we’ll get to that).

The key elements for attracting bluebirds are the same as most other species; food, water, shelter, and nesting sites. Let’s address the specifics of each one to ensure you have the best chances of receiving a little blue visitor! Oh, and before you continue reading, be sure you are within the distribution range of a bluebird species.

Bluebird Food Tips

There are a variety of foods that Bluebirds prefer. If you can consistently supply them with any of the following, you’ll be blessed by their presence regularly.

Suet: Not just any suet, but suet that has insects and fruit blended into it. Bluebirds are partial to crumbles and shreds of suet which you can do by using a cheese grater on suet blocks. Do this when the suet is cold for the best results.
Mealworms: Their favorite food! Can you imagine if your neighbor put your favorite snack in a bowl in their yard? I don’t know about you, but I’d be there on the regular. Dried mealworms should be placed on a tray or platform feeder. If you’re next level, you could try raising your own mealworms. I don’t have the stomach for it, but if you introduce live mealworms into your yard, the birds will love you.
Berry Bearing Plants: When you plant holly, sumac, elderberry, or juniper shrubs in your yard, your chances of attracting foraging bluebirds are significantly increased. Bluebirds love to eat the berries produced by these plants. Never use insecticides that can inadvertently poison wildlife.

Bluebird Water Tips

Your current bird bath may already be plenty suitable. Bluebirds like fresh water daily in a low basin for bathing and drinking. Fill with about two inches of water every day for a five-star experience. Other tips include:

Add Running Water: A simple fountain to your bird bath will grab the attention of many birds. Bluebirds, in particular, prefer running water and will opt to visit a nearby stream, river, or creek before they stop by your bird bath. The sound of the bubbling water will convince them your yard has what they crave. Additionally, the movement of the water glistens in the sun and catches their eye.
Bird Bath Size: You will inevitably attract many species of birds as you enhance the conditions and offerings of your yard. This is great but will create some natural competition for resources. When you purchase a large bird bath that can host many visitors at once, the competition is eliminated, and birds will be more likely to swing through for a sip or dip.
Heat Things Up: Turn up the heat when temperatures begin to drop. Freezing temperatures mean that liquid water is hard to come by. When you add a bird bath heater, you’re providing birds with a winter life source. Even if you’re in an area that doesn’t normally freeze, climate change means there are many inconsistencies in the weather and increased unreliability that nearby flocks have suitable water sources during the winter.

Bluebird Shelter and Nesting Box Tips

With the introduction of invasive species like House Sparrows and European Starlings came intense competition for nesting sites. These birds attack and con to lure birds out of their nests. Bluebirds are cavity-nesters, and since they cannot excavate their own, they rely on reusing old woodpecker cavities or finding a naturally occurring cavity. Luckily, there are a few ways you can help:

Open Wide: Bluebirds like semi-open spaces with evenly spaced mature trees and low, dense foliage near an open patch of grass. As mentioned above, planting berry-producing shrubs is a great way to enhance the suitability of your yard. These will provide food and shelter. Do not remove dead trees and snags. These create valuable nesting and roosting options.
Offer Housing: The bird housing market is a dismal one. Rising competition leaves minimal or zero options for bluebirds. Many bird lovers and conservationists have created bluebird trails lined with nesting boxes that alleviate the stress and unlikelihood of securing a suitable nesting site. If you don’t have a yard but would still like to help out, consider volunteering or seeking permission to place nesting boxes in a nearby park or wildlife preserve.
- Housing Requirements: Birdhouses and nesting boxes should be placed four to seven feet off the ground along the edge of wooded areas and in open spaces. Use redwood, cedar, or fir wood. Cedar is the top recommendation due to its durability and insect-resistant nature.
  - Install a wooden guard to deter sparrows, starlings, snakes, and mammals from attempting an attack. Reflective objects on or near the birdhouse or nesting box keep sparrows at bay without interfering with bluebirds.
  - Clean the birdhouse each season to kill bacteria and parasites, and prevent disease. Use a weak bleach solution of nine parts warm water to one part bleach. Allow the birdhouse to dry completely before returning it to its tree or post.
  - Leave the birdhouse its natural color, or paint it a neutral color. This allows the birdhouse to have a natural camouflage and will reduce the chance of predator interference.
  - Provide nesting materials like pine needles, twigs, animal hair, and grass clippings.

Conclusion

Now that you’ve graduated from the Western Bluebird crash course, you’re equipped to share facts and try your hand at getting a few bluebird visitors. Don’t be discouraged if they don’t show up immediately. They will take some time to acclimate to the offerings, but once they figure it out, they’re likely to return each year. These delicate and enthusiastic birds bring so much joy to the world. I hope you get out there and appreciate them very soon!

FAQ

Question: What is the lifespan of a Western bluebird?

Answer: The oldest recorded Western Bluebird was eight years and eight months old. On average, scientists believe they live anywhere from six to ten years. After enduring their first winter and year of life, a Western Bluebird’s odds of survival increase dramatically.

Question: Are Western Bluebirds native to California?

Answer: Western Bluebirds are year-round residents of California. Their location depends on the season. They flee the mountains as temperatures drop and migrate towards warmer areas.

Question: Is Western bluebird a carnivore?

Answer: Western Bluebirds are omnivores that consume a diet composed of insects, fruits, nuts, and berries. Grasshoppers, crickets, sumac, juniper, holly, earthworms, snails, and spiders are everyday meals for these perch hunting birds.

Question: What is the song of a Western bluebird?

Answer: Listen for a quiet “kew” repeated serveral times from a perch or in flight.

Research Citations

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