eastern bluebird
Sialia sialis
Scientific Name: Sialia sialis
Common Name: Eastern bluebird
Habitat: Semi-open habitats, with sparse understory and ground cover, including agricultural and urban areas.
Physical Description: The eastern bluebird is 6-8 inches long and has a wingspan of 9-12 inches. Eastern bluebirds are sexually dimorphic as adults and juveniles, meaning both sexes look different as adults and juveniles (Figure 1). Adult males have blue upper parts with red-orange throat and breast, and a white belly. Adult females have blue-gray upper parts, a gray-brown wash on back, dull blue wings and tail, and a paler orange throat and breast. Juveniles have browner plumage with white streaking above and spotting below (Figure 2).
Weight: 1.0 – 1.1 ounces
Reproductive Rate: 3-7 eggs, with an average of 5. Incubation 13-16 days. May raise 2 or 3 broods a year.
Lifespan: 6-8 years in wild, 10 years in captivity
Dispersal & Home Range: Juveniles form flocks of several families that range widely but usually stay in the vicinity of their birth area. In resident populations, late-season fledglings may stay with their parents through the winter. Nesting territories range from 2 to 20 acres, and become smaller as the season progresses, possibly due to increasing insect availability. Territory size also decreases as available nesting cavities in an area increase. Winter home ranges are larger than nesting territories.
Common Name: Eastern bluebird
Habitat: Semi-open habitats, with sparse understory and ground cover, including agricultural and urban areas.
Physical Description: The eastern bluebird is 6-8 inches long and has a wingspan of 9-12 inches. Eastern bluebirds are sexually dimorphic as adults and juveniles, meaning both sexes look different as adults and juveniles (Figure 1). Adult males have blue upper parts with red-orange throat and breast, and a white belly. Adult females have blue-gray upper parts, a gray-brown wash on back, dull blue wings and tail, and a paler orange throat and breast. Juveniles have browner plumage with white streaking above and spotting below (Figure 2).
Weight: 1.0 – 1.1 ounces
Reproductive Rate: 3-7 eggs, with an average of 5. Incubation 13-16 days. May raise 2 or 3 broods a year.
Lifespan: 6-8 years in wild, 10 years in captivity
Dispersal & Home Range: Juveniles form flocks of several families that range widely but usually stay in the vicinity of their birth area. In resident populations, late-season fledglings may stay with their parents through the winter. Nesting territories range from 2 to 20 acres, and become smaller as the season progresses, possibly due to increasing insect availability. Territory size also decreases as available nesting cavities in an area increase. Winter home ranges are larger than nesting territories.
bluebird nest box designs
Florida Bluebird Society (FLBS) Design
UF EDIS How to Build Eastern Bluebird FLBS Nest Box
Video - Building a FLBS Nest Box
FLBS Nest Box Design Plan
North American Bluebird Society (NABS) Design
UF EDIS How to Build Eastern Bluebird NABS Nest Box
Video - Building a NABS Nest Box
NABS Nest Box Design Plan
Gilbertson (GILS) Design
UF EDIS How to Build Eastern Bluebird GILS Nest Box
Video - Building a GILS Nest Box
GILS Nest Box Design Plan
Peterson (PET) Design
UF EDIS How to Build Eastern Bluebird PET Nest Box
Video - Building a PET Nest Box
PET Nest Box Design Plan
Nest Box Recommendations
- Choose a nest box design that is suitable for your region. If needed contact local experienced birders for recommendations.
- Construction Material - help box last, maintain safe temperatures and keep safe from predators.
- solid wood, 3/4 to 1 inch think
- pine should have exterior only (and not front entrance wall) sealed using water-seal paint, such as Thompson's Water-seal
- cedar is ideal but may be harder to find and more expensive
- DO NOT
- use pressure-treated wood, material such as milk cartons or cardboard as they will be destroyed by weather and potentially predators.
- metal, will result in severe overheating
- clay or ceramic, as they break and retain heat
- Access for monitoring
- Entry hole size varies depending on region and is critical in keeping predators and other invasive birds out.
- Kerfs on front wall under entry hole to allow adults to perch and feed young and to aid chicks to exit the box when they are ready to fledge.
- Roof designed to be weather resistant and keep predators out.
- Floor size large enough to accommodate clutch and help nestlings maintain body temperature.
- Water resistance and drainage to keep interior of box dry and help with air circulation.
- exterior seams
- floor drainage
- paint/stain
- vents
- Mounting and predator deterrence
Monitoring Nest Boxes
Florida Bluebird Society Principles:
- Always put the interest of the birds first. Be conscious of their welfare at all times as they are our highest priority.
- Consider the impact of your activities on the birds before you take action.
- Ensure that nestboxes and any other structures you provide for birds are safe.
- Obey bird protection laws. Do not touch nests, eggs, or birds.
- Keep disturbances to a minimum. Only open a nestbox when necessary to collect data. Follow the Florida Bluebird Society’s Nestbox Monitoring Protocol.
Florida Bluebird Society Nestbox Monitoring Protocol
1. Ensure the Safety and Well-being of the Birds
No observation should jeopardize the safety or well-being of the birds. Minimize disturbance, all activity should be done quietly and quickly to avoid stressing the birds.
2. Plan Ahead to Minimize Disturbance
Monitor nestboxes only for data collection. Planning is important to maximize monitoring efforts and minimize time at the nestbox.
3. Caution is the Key
If the bird does not flush from nest on approach lightly tap the side of the box before opening it very slowly. If the adult doesn’t get off the nest, carefully close the box and leave the area. When opening the box or tapping the side of the open box, stand to one side, not in front of the box. This is for two reasons: 1. If there is a parent in the box, this will let the bird fly out, and 2. standing to the side will protect you if there is any other creature in the box, such as a snake.
4. Hands OFF
Do not handle the bluebird nest, eggs, nestlings or parents during an active nesting period. In Florida, individuals wanting to handle the bluebird nest or its contents during the active nesting period need to possess the proper federal and/or state permits. An active nesting period is defined as follows: Nest building, egg laying, egg incubation or nestlings present. Please note, if a nest was built but no breeding activity was observed, it is still considered active until the end of the full breeding season.
Use a camera phone, baroscopic camera, mechanic’s mirror or dental mirror to view the inside of the nest to count the eggs or nestlings. If unable to make an accurate count of the eggs or nestlings, indicate it is a minimum number rather than handle the nest contents.
English sparrows and starlings are not protected by the Federal Migratory Bird Act. The nests, eggs, nestlings and any adults should be removed if found in a nestbox. House sparrows are small enough to enter a nestbox through a 1½” entry hole and will destroy bluebird eggs. They will attack and kill both nestlings and adult birds trapped inside a nestbox. It is important to recognize the birds and nests protected by the Federal Migratory Bird Act and those non-native species which are not protected.
5. How Often and When
Nestboxes should be monitored once a week in order to obtain accurate data, to inspect and make any necessary repairs to the nestboxes, to determine the status of the nestlings, and to avoid interfering with the natural nesting schedule of the chicks. Monitoring weekly is sufficient to gather all the necessary information and to determine the status of the nestbox and the chicks.
Nestboxes opened too frequently can cause a number of problems including abandonment, increased predation, and premature fledging.
There also are certain times when nestboxes should not be opened. DO NOT OPEN when:
6. Cleaning the Nestbox (Click here to watch a video on cleaning nestboxes)
Nestboxes should be cleaned out at the end of the nesting season, necessary repairs made during the off-season, and inspected again immediately prior to the start of a new nesting season to ensure that the boxes are ready to be used by bluebirds. Although it is not necessary, a nest can be removed during nesting season after chicks have fledged or after a nest failure, including any nest inactive for at least one month, but extreme caution must be observed to ensure that the nest truly is inactive.
Caution should be used when cleaning out a nestbox. Wear gloves and stand with the wind at your back to ensure you don’t breathe in any waste material. The nest should be placed in a bag (you can place a plastic bag over your hand and invert it like a gloved to grab it with) and disposed of in the trash. Do not throw it on the ground where it could attract predators and possibly endanger any further nesting in that nest box. If desired, brush out the interior, again make sure the wind is at your back. Wash your hands well with soap and sanitizer immediately afterwards.
7. Other guidelines
No observation should jeopardize the safety or well-being of the birds. Minimize disturbance, all activity should be done quietly and quickly to avoid stressing the birds.
2. Plan Ahead to Minimize Disturbance
Monitor nestboxes only for data collection. Planning is important to maximize monitoring efforts and minimize time at the nestbox.
- Learn to identify the nests of different species
- Move away from active nestboxes when recording the data to avoid unduly stressing the birds
- Plan a regular schedule of visits to the nestbox in order to obtain an accurate record of the nesting events
- Learn the normal time frame for the nesting events
3. Caution is the Key
If the bird does not flush from nest on approach lightly tap the side of the box before opening it very slowly. If the adult doesn’t get off the nest, carefully close the box and leave the area. When opening the box or tapping the side of the open box, stand to one side, not in front of the box. This is for two reasons: 1. If there is a parent in the box, this will let the bird fly out, and 2. standing to the side will protect you if there is any other creature in the box, such as a snake.
4. Hands OFF
Do not handle the bluebird nest, eggs, nestlings or parents during an active nesting period. In Florida, individuals wanting to handle the bluebird nest or its contents during the active nesting period need to possess the proper federal and/or state permits. An active nesting period is defined as follows: Nest building, egg laying, egg incubation or nestlings present. Please note, if a nest was built but no breeding activity was observed, it is still considered active until the end of the full breeding season.
Use a camera phone, baroscopic camera, mechanic’s mirror or dental mirror to view the inside of the nest to count the eggs or nestlings. If unable to make an accurate count of the eggs or nestlings, indicate it is a minimum number rather than handle the nest contents.
English sparrows and starlings are not protected by the Federal Migratory Bird Act. The nests, eggs, nestlings and any adults should be removed if found in a nestbox. House sparrows are small enough to enter a nestbox through a 1½” entry hole and will destroy bluebird eggs. They will attack and kill both nestlings and adult birds trapped inside a nestbox. It is important to recognize the birds and nests protected by the Federal Migratory Bird Act and those non-native species which are not protected.
5. How Often and When
Nestboxes should be monitored once a week in order to obtain accurate data, to inspect and make any necessary repairs to the nestboxes, to determine the status of the nestlings, and to avoid interfering with the natural nesting schedule of the chicks. Monitoring weekly is sufficient to gather all the necessary information and to determine the status of the nestbox and the chicks.
Nestboxes opened too frequently can cause a number of problems including abandonment, increased predation, and premature fledging.
There also are certain times when nestboxes should not be opened. DO NOT OPEN when:
- nestlings are more than 12 days old
- it is raining in order to keep the nest from getting wet
- the female is laying eggs during the early mornings
6. Cleaning the Nestbox (Click here to watch a video on cleaning nestboxes)
Nestboxes should be cleaned out at the end of the nesting season, necessary repairs made during the off-season, and inspected again immediately prior to the start of a new nesting season to ensure that the boxes are ready to be used by bluebirds. Although it is not necessary, a nest can be removed during nesting season after chicks have fledged or after a nest failure, including any nest inactive for at least one month, but extreme caution must be observed to ensure that the nest truly is inactive.
Caution should be used when cleaning out a nestbox. Wear gloves and stand with the wind at your back to ensure you don’t breathe in any waste material. The nest should be placed in a bag (you can place a plastic bag over your hand and invert it like a gloved to grab it with) and disposed of in the trash. Do not throw it on the ground where it could attract predators and possibly endanger any further nesting in that nest box. If desired, brush out the interior, again make sure the wind is at your back. Wash your hands well with soap and sanitizer immediately afterwards.
7. Other guidelines
- Do not put up more boxes than you are willing to monitor on a regular basis. Please take boxes down if you are not going to monitor anymore. They can get filled with invasive, non-native species such as the house sparrows or Cuban tree frogs and cause long-term harm to the environment
- If some parts of your regular trail become too burdensome to you for monitoring and managing, we suggest you try and get nearby homeowner to take over or take it down
- Do not put boxes up without effective predator guards
Recording and Sharing your Nest Box Data
Help contribute to scientists and bird data by submitting your data to Cornell’s NestWatch. You will be helping scientists by collecting valuable data on the successes and failures of nesting birds. Check out or download the Nestwatch datasheet:
More Eastern Bluebird Resources