Eastern Bluebird Guide (Sialia sialis)

Latest posts by Reina Esser (see all)

I am always impressed by how much there is to learn about even the most familiar birds. The Eastern Bluebird is no different. Although those who have spent time east of the Rocky Mountains are acquainted with the small blue flashes of feathers that grace our backyards, the details of their exciting lives are still worth discovering!

You never know which bits of information your brain will hold onto throughout your birding journey. Taking time to absorb the basics about familiar species is the perfect way to ease into a hobby with an overwhelming amount of information to learn.

When I first started birding, I initially limited my scope to common backyard birds, but even that was a bit of an information overload. Instead of memorizing the colors, calls, and mannerisms of every backyard bird, I decided to choose two each week. This gave me a realistic scope of time to get to know the basics, and I never walked away feeling defeated.

Eastern Bluebirds are great beginner birds to learn about because there isn’t much overlap with look-alike species like the Western Bluebird or the Mountain Bluebird. Additionally, they’re pretty easy to spot, and this will only build confidence in your birding ability. (Cardinals are another great beginner bird!)

When you see the powdery blue feathers of an Eastern Bluebird, there is a feeling of excitement. Their colorful presence brings any scene to life. Although they are regulars at backyard feeders, their cheery company is always delightful to behold.

There are seven subspecies of Eastern Bluebirds that are recognized by their coloration and range. These subspecies include:

  • S. s. sialis
    • Found in southeastern Canada, east and the central United States, and northeast Mexico
  • S. s. bermudensis
    • Found in Bermuda
  • S. s. nidficans
    • Found in east and central Mexico
  • S. s. fulva
    • Found in the southwestern United States to central Mexico
  • S. s. guatemalae
    • Found in southeast Mexico and Guatemala
  • S. s. meridionalis
    • Found in El Salvador, Honduras, and north Nicaragua
  • S. s. caribaea
    • Found in east Honduras and northeast Nicaragua

How to Identify an Eastern Bluebird

Size & Shape

The Eastern Bluebird is an adorable small thrush that has a large head with big eyes and a round body. They have an upright stance atop short legs with a short tail that follows behind them. They are little birds that are about two-thirds the size of an American Robin. They have short pointed bills that look similar to the tip of a large black sunflower seed.


The magic of the Eastern Bluebird is its stunning blue plumage. Males have a rich royal blue head, back, and wings that contrast beautifully against orange rusty-colored throats and breasts. Their flight feathers and tail feathers have subtle black accents along the outer edges. Females and juveniles are much less vibrant and appear grayish brown with only slightly blue wings and tails. Juveniles may also display white spotting on their backs and chest.

eastern bluebird on a branch

Mountain Bluebirds and Western Bluebirds

While there is typically no overlap in the range of these different bluebird species, there is a chance that you could encounter both an Eastern and Western Bluebird in certain areas of Texas and around the Rocky Mountains.

Mountain Bluebirds are the easiest to differentiate as they do not have the same rusty orange-colored breast present in the Eastern and Western Bluebird. Instead, they are blue all over with gray underparts.

Western Bluebirds appear incredibly similar to Eastern Bluebirds. The Western Bluebird has brighter blue feathers that extend to its chin and around the neck. An Eastern Bluebird has an orange-to-white chin.

western bluebird
Western bluebird

Where Does an Eastern Bluebird Live: Habitat

The Eastern Bluebird is the most widespread of the three bluebirds. East of the Rocky Mountains and beyond to southern Canada, Mexico, and Honduras, the Eastern Bluebird thrives in open meadows and land with a scattering of trees. They can usually be found along roadsides on utility lines, farms, suburbs, parks, and gardens. Bluebird trails with nesting boxes are also popular hotspots.

sialia sialis distribution
Green — year round Yellow — breeding seasons Blue — nonbreeding seasons

Eastern Bluebird Diet and Feeding

Just like humans, the diet of the Eastern Bluebird depends on the season. During the summer, these busy birds can typically be found catching a variety of insects, such as crickets, grasshoppers, caterpillars, and beetles. Insects are a vital part of their diet, making up 68% of it. As autumn temperatures cool things off and insects become harder to find, the Eastern Bluebird relies on fruits like blackberries and wild grapes while also munching on a variety of plants such as honeysuckle, dogwood, and cedar.

To catch the ideal meal, Eastern Bluebirds will perch atop high branches or fence posts. As unsuspecting insects make themselves known, the bird will swoop down to catch them in mid-flight or on the ground. They can spot prey up to 60 feet away.

During the winter, Eastern Bluebirds migrate towards suitable feeding grounds if the supply of food in their current region looks low.

When it comes to water, a running source is favored, but a birdbath or pond will suffice as a daily watering hole. I always enjoyed many Eastern Bluebirds splashing about in my birdbath on warm summer days.

Eastern Bluebird Breeding

Monogamous by nature, Eastern Bluebirds welcome the mating season in the spring and summer. Males attract females to their chosen nesting sites by perching near the cavity, fluttering their wings, and taking nesting materials in and out of the hole as if they were building a nest…but they never actually build one. He leaves that part for his lucky lady. Once a match has been made, the female takes over all nest-building responsibilities.

Eastern Bluebird Nesting

Nests are created in natural cavities and holes that are discovered in decaying trees such as pine or oak. These are often created by other species, such as woodpeckers, and repurposed by other birds to their needs. Due to the dwindling amount of naturally occurring cavities, many Eastern Bluebirds rely on nesting boxes placed by homeowners and conservationists.

Interestingly enough, Eastern Bluebirds that have a few more breeding seasons under their belts are more likely to opt for a nesting box. Younger birds may be skeptical or hold out hope that they will find the perfect cavity elsewhere. Either way, these birds like small spaces that range from four to six inches of space in the interior of their chosen nesting location.

Females take on the task of building the nest and use many different plant and animal materials to do so. Everything from grass, pine needles, horse hair, turkey feathers, and stems are all used to create the small cup that will cradle her eggs. The nest building process takes about ten days of hard work for the female to build.

I have found that many Eastern Bluebirds in my region enjoy the nesting balls I hang each spring. Each nesting ball is filled with a mixture of fibers and dog hair. Watching them remove a small tuft of hair as they make their way back to their nesting box is extremely cute and satisfying.

bluebird at its nesting box

Eastern Bluebird Eggs

After a suitable nest is built, the female will lay about three to seven small light blue eggs and spend the next two weeks incubating them. Once hatched, both parents pitch in to collect enough food to feed the altricial young.

Scientists suggest that the blue nature of this bird’s eggs indicates there are high amounts of a bile pigment called biliverdin present in the bird’s body. In humans, this pigment is produced in the spleen and is responsible for making bruises that awful blue-green color we all love. In birds, this adaptation serves the eggs by allowing for optimal amounts of light and heat to be absorbed, giving its occupant a wing up when growing.

After seven days of around-the-clock brooding, the expectation is that the chicks become slightly more self-sufficient and begin to get their wits about them. Typically, fledging takes place fifteen to twenty days after hatching. It’s kind of a harsh turnaround time if you ask me.

Fledglings will appear gray with spotted breasts. As they age, their namesake blue coloration begins to develop, and the spots disappear.

A female will usually raise two broods per mating season. In some cases, the young will stay near the nest to aid their parents in raising their second brood. This practice is much more familiar in Western and Mountain Bluebirds.

Juveniles will begin the mating process the summer after they are hatched.

Eastern Bluebird Population

eastern bluebird

I am happy to report that a healthy population of Eastern Bluebirds still exists. With a breeding population of 23 million, the species is of low conservation concern.

With the introduction of the European Starling to North America in the early twentieth century, competition for nesting sites became fierce. Luckily, nesting boxes and bluebird trails offered enough relief to spare the species. If you opt to use nesting boxes, be sure the entrance is small enough that a Starling is unable to enter.

Eastern Bluebird Predators

There are so many dangers to look out for in the world, and for the Eastern Bluebird, the trials never end. The usual predators of the Eastern Bluebird include house cats, American Kestrels, snakes, raccoons, black bears, and even fire ants. Chipmunks and squirrels are particularly keen on eggs and nestlings.

Competition for nesting sites could also be classified as a form of predation from European Starlings. Starlings are fierce, violent, and particularly cunning and clever when it comes to removing birds from their nest.

Although these little birds are cute, they can be territorial during the breeding season or when predators are nearby. Both sexes flick their wings and make low-pitched warbling noises to fend off unwanted guests. Listen for a warning cry from males as they attempt to deter the danger. Females sing to alert nearby males that they need them to come to lend a hand in the defense department.

american kestrel
American Kestrel

Eastern Bluebird Lifespan

Surviving the first year of life is a challenge that all birds face. Unfortunately, many Eastern Bluebirds do not pass this trial. For those who make it beyond their first year, their chances of survival increase drastically. Eastern Bluebirds who make it past their first year of life are likely to live anywhere from six to ten years!

Tips for Attracting Eastern Bluebirds

While I’ve spent the entirety of this guide discussing the Eastern Bluebird, these tips will help you attract Western and Mountain Bluebirds too.

When it comes to your yard, keeping things fairly open and clear will give bluebirds the hunting advantage they need. Open areas are always preferred, and dead trees and branches provide natural cavities for nesting.

Planting trees, shrubs, and fruits that are native to your area will also significantly increase your chances of receiving bluebird visitors in the winter. If you’re unsure where to start, junipers, serviceberries, elderberries, dogwoods, and sumacs will steer you in the right direction.

As mentioned earlier, bluebirds prefer a running source of water as opposed to a still pond or birdbath, so enlisting the help of a fountain will make for many happy birds. Use a fountain heater in the winter months to keep their vital water source available. Remember, once you start providing, it’s essential to remain consistent.

Get rid of the pesticides! Keep things natural. If you need to use a weed killer, consider using any of Monty Don’s animal-friendly methods.

Stock feeders with mealworms, either dried or live. This creepy crawlies are irresistible to our beautiful blue friends and are a nutrient-rich food source.

Place bluebird boxes out well in advance of nesting season so birds can scope things out beforehand. For the best chances of survival, choose nesting boxes with an entrance that is no larger than 1.5 inches. This will keep other birds and larger predators at bay. If mounting to a post, consider using a predator guard to keep unwanted visitors from climbing up.

Now you are equipped with tons of interesting and vital information for not only identifying Eastern Bluebirds but for attracting them to your yard as well. Happy birdwatching, friends!

angry eastern bluebird


Question: What does it mean to see an Eastern bluebird?

Answer: Bluebirds have been known to symbolize the arrival of good news, joy, and hope. Some believe that Eastern Bluebirds represent a bond between loved ones who have passed and the living world.

Question: How rare is a blue bird?

Answer: Bluebirds are common in most areas, but you’ll need to know where to look. Focus on open fields, parks, gardens, and orchards. Recently cut or burned areas of forest will be new territory that bluebirds are excited to explore.

Question: What do Eastern Bluebirds eat?

Answer: Eastern Bluebirds have a varied diet that is comprised of mostly insects. Favorite insects include crickets, grasshoppers, beetles, and worms. At feeders, Eastern Bluebirds are partial to mealworms, both dried and living.

Research Citations

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