This article has been adapted from theAudubon Birdhouse Bookby Margaret A. Barker and Elissa Wolfson.You can also download aprintable PDF of the instructionshere.
In the natural world, all three species of North American bluebirds—the Eastern, Western, and Mountain Bluebirds—seek tree cavities or woodpecker holes for nesting sites. But today, natural cavities can be hard to find. Competition for these limited sites is a huge problem, especially in early spring. Old and rotting trees often are removed. Not long ago, many bluebirds nested in wooden fence posts, especially around farms. Many of those have been removed or replaced with treated wood, plastic, or metal posts. A well-built and well-placed blue-bird nest box in your own backyard or nearby park can help boost local populations.
Even with nest boxes in place, bluebirds must compete with both introduced and native species that also want to call these nest boxes their home. Knowing where to place and where not to place bluebird nest boxes is critical. Chickadees and titmice, for example, prefer nest boxes near or under mature trees or within woodlands and forests. By contrast, bluebirds like nest boxes out in the open; even a small yard with open spaces will suit a bluebird. Most important, bluebirds need to live near a ready supply of insect food.
Since bluebirds defend large feeding territories around their nests—one or two acres in early spring—they don’t want to nest close to other bluebirds. Tree Swallow pairs won’t nest close to one another either. So reduce competition by installing pairs of bluebird nest boxes no more than fifteen to twenty feet apart. Bluebirds may nest in one, and swallows, chickadees, or titmice in the other. This “peaceable kingdom” occurs for practical reasons: These bird neighbors, by and large, do not share the same food supply. But the nest box “pairing” idea is not with-out differing opinions. Some people believe it encourages other species more than it accommodates bluebirds. Others put up a second box nearby only when a non-bluebird species has claimed a nest box first.
Ironically, the cutting of Eastern forests, especially pine woods, for agriculture in the nineteenth century may have actually benefited Eastern Bluebirds by creating additional foraging and nesting habitat. More recently, however, their populations have been affected by loss of habitat and tree cavities, unusually cold winters in the 1960s and 1970s, egg and chick predation, and competition for nesting sites by introduced House Sparrows and European Starlings.
Eastern Bluebird Basics
Range: Eastern Bluebirds are year-round residents in the southern United States. They typically begin nesting as early as January in the south and in March in the northern United States and southern Canada. They are also found in parts of Mexico, Central America, and Bermuda.
Field marks: Males are bright blue above and rusty orange below with a white belly. Females look similar but have a blue-gray back and lighter orange underparts. Both sexes are seven inches long and stout billed. In flight, look for short blue wings and tail.
Voice: The call is a musical chur-wi or tru-ly. The song is a series of three or four soft musical notes, often described as a warble.
Feeding: Keen-eyed Eastern Bluebirds feed on ground-dwelling insects, including beetles, crickets, grasshoppers, and caterpillars, which they can spot while perched as far as 150 feet away. They pounce upon their insect prey, then fly to a perch and strike it against a hard surface before feeding—or they just catch and eat insects in the air. Adults also feed juicy, high-protein spiders to nestlings. Wild berries are also eaten, especially in colder months. At feeders, offer raisins, currants, suet mixes, and mealworms (live or freeze-dried).
Western Bluebird Basics
Range: Western Bluebirds are found in southwestern Canada, Mexico, and many western U.S. states. They are medium- to short-distance migrants that winter in the southern part of their range and begin nesting in early April.
Field Marks: Adult males have cobalt blue wings and tails as well as an all-blue head, chin, and throat, and a white belly. The upper breast is chestnut with varying pat-terns of blue and gray. The back may be partly or entirely chestnut. Females are a paler, grayer version of the male.
Voice: The song is a series of call notes described as few or kew. Chatter calls sound like cut-cut-cut. Soft tch-tch-tch calls can also be heard.
Feeding: Western Bluebirds eat insects in warm weather, and fruits and berries in winter. Mistletoe and juniper berries are favorites, and they love mealworms at feeders. They are often seen “fly catching” or foraging on the ground, using low branches as a jumping-off place.
Mountain Bluebird Basics
Range: Mountain Bluebirds are found primarily in the western mountains from east-central Alaska to south-central Mexico, migrating to the northern parts of their range to begin nesting in late April.
Field Marks: Breeding males have a turquoise-blue back, a paler blue breast, and white belly and under tail coverts. Females and juveniles are gray above and have pale blue wings and tail and a buffy chest. The adults are slightly larger and thinner-billed than other bluebirds; their wings are proportionately longer than the other bluebird species.
Voice: The Mountain Bluebird’s call is a low fewor chur, described as a soft burry chortle. The male’s short, subdued warbling song has been called “hauntingly beautiful.”
Feeding: Mountain Bluebirds feed on insects, including weevils, wasps, beetles, bees, grasshoppers, caterpillars, and crickets. They often “hover hunt” like kestrels when forag-ing, or hunt from low perches before dropping or darting upward to capture prey. In late winter, they rely on native berries of mistletoe, hackberries, juniper, and hollies.
Nesting Details
In southern states, bluebirds may start looking for nesting sites as early as January, so have nest boxes ready for them. However, this may be two to three months later at their northern limit. During the breeding season, check nests at least once a week. Since bluebirds typically lay eggs in the morning, the ideal time to check nests is in the afternoon.Include perches in your bluebird landscape. Both adult and newly fledged bluebirds like to sit on small trees or fence posts from which they can scout for insects on the ground. Bluebirds are mostly insectivorous, but they also eat wild berries. Offering mealworms near nesting sites, and planting berry-producing grapes, blackberries, dogwood, elderberries, and serviceberries, might induce bluebirds to stay around your property. Supply fresh water for both drinking and bathing. Many “bluebirders” remove old nesting material from a nest box right after the young have fledged; this task can be repeated several times during the nesting season. At the end of the nesting season, clean out the nest box one last time and make any needed repairs. Bluebirds and other species often use nest boxes for roosting in cold weather.
Nesting habits:Female bluebirds build tight cup nests atop a looser built base. Thin bark strips, pine needles, and dry grasses are typical nesting materials. The inner nest cup may be lined with softer, finer materials.
Eggs:Range from two to seven pale blue and, very seldom, white eggs. First clutches average five to six eggs; second clutches average four to five eggs. Eastern Bluebirds typically have two clutches a year, but in warmer climates, three clutches are common. In the northern part of their range, Mountain Bluebirds are known to lay larger but fewer clutches than Eastern or Western Bluebirds.
Egg-laying:Typically one egg each day until the clutch is complete.
Incubation:Female incubates for twelve to fifteen days. Male feeds incubating and brooding female.
Days to fledge:Fledge dates for Eastern and Western Bluebirds may vary from sixteen to nineteen days. Mountain Bluebirds typically fledge within 17 to 21 e days.
Post-fledging: Within a protected wooded area, both bluebird parents feed the fledglings after they leave the nest and while the young are practicing their flying skills. This period may last up to a few weeks after the young learn to fly. The male may continue to assist fledglings while the female begins building a second nest a week or so after the first brood has fledged. First-brood young sometimes help feed their second-brood siblings.
Build Directions
In the 1960s, self-taught naturalist Dick Peterson noticed the decline of local bluebirds. As a way to help them, he designed a wooden bluebird box to replace their preferred but scarce natural tree holes. His unique “Peterson” nest box, with its signature sloping roof to thwart predators, is credited with helping restore bluebird populations in Minnesota and elsewhere. In the late 1970s, Peterson received an outpouring of letters and requests for nest box plans following a widely read Minneapolis Star Tribunearticle on his bluebird work. Inspired by this surge of interest, in 1979 Peterson partnered with the National Audubon Society’s Minneapolis chapter and formed the Bluebird Recovery Program (BBRP) of Minnesota—the nation’s first state bluebird organization. Keith Radel, a BBRP coordinator who knew Peterson, says his legacy extends beyond designing a nest box and founding the organization: “Dick’s real influence was teaching people responsible ways to keep birds safe—how to identify and then fix problems at the nest box. His insistence on weekly nest checks has been critical to bluebird recovery.”
Materials:
• Lumber: cypress (used here), white cedar, hemlock, or local weather-resistant wood with low toxicity
• One 1x10x11” (roof)
• Four 1x6x10” (front, sides, and back)
• Two 1x6x4” (floor and inner roof)
• One 2x2x9” (pole-mounting block)
• Exterior screws: twelve 1 5/8” (basic construction); two to six 1 1/4” (roof to inner roof); and two 2” (pole mounting block to back)
• Caulk or sealant (sealing between top and inner roof)
• One 2 1/2” galvanized nail (bent, latch nail)
• Mounting: One 1/2”x5’ galvanized metal conduit, one 1/2”x4’–5’ steel rebar (for stake), and one conduit coupler
Steps:
1. Hole saws were used for the xbox entrance and ventilation holes, as well as the mounting block. Atable saw with its blade lowered was used for the drip kerfs on the underside of the roof and for the ladder kerfs on the inside of the front.
2. The back piece of the xbox is attached to the inner roof. Two deck screws (1 5/8”) are installed with an impact driver.
3. Test-fit the attached back, unattached sides and inner roof. Use a pencil to mark the placement of the recessed floor. Drive in screws.
4. Top of sides are attached to the inner roof above the entry hole.
5. Pivot screws, driven into the front piece from the bottom of both sides, allow the front to open easily for checking and cleaning.
6. One galvanized nail (2 1/2”) is bent to create the latch nail. Drill the latch nail hole slightly downward.
7. The mounting block for the gilbertson pole system is installed on the back of the xbox with two exterior deck screws (2”). Note the predrilled 3/4” hole on the mounting block.
8. Apply a bead (line) of all-purpose low Voc caulk to the top of the inner roof prior to installing the exterior roof.
9. The gilbertson pole system is easy to assemble. Drive rebar into the ground, leaving two feet above ground. Attach conduit coupler to end of conduit. Tighten upper, shorter screw against conduit. Slip coupler over rebar. Tighten lower, longer screw against rebar. Clean pole with steel wool and coat it with furniture polish. Add baffle if needed.
Box Placement
Eastern Bluebirds prefer forest clearings and semi-open country with scattered trees. Big yards, orchards, and cemeteries are good nest box sites. The preferred nesting habitats for Mountain Bluebirds consist of short grass areas interspersed by a few trees. Western Bluebirds can be found in woodland edges and open, park-like forests, including those that have been thinned or lightly logged. Space individual or paired bluebird nest boxes at least 300 feet apart or out of the line of sight from the nearest bluebird nest box.
Mounting:The Xbox is designed to be mounted onto a half-inch conduit/rebar pole, called the “Gilbertson system”. Avoid mounting nest boxes on fences or trees where climbing mammals or snakes are present. Use predator guards to further block nest box access.
Height: Bluebirds nest within a wide range of heights, from two to 50 feet. Mounting at eye level provides easy checking; however, if cats or other predators are problems, hang nest boxes at least six to eight feet from the ground.
FAQs
What direction should a bluebird box face? ›
- Position the nest box so that the entrance hole is facing east and towards open habitat.
- To decrease competition from Tree Swallows, you can pair nest boxes about 15–20' apart, with pairs of houses about 300' from each other.
Measuring from the ground to the bottom of the box, mount your bluebird box at least four feet, but no more than 15 feet above the ground. Whenever possible, mount bluebird nesting boxes on poles made of metal or sunlight-resistant PVC pipes.
Why won't bluebirds use nest boxes? ›A wide expanse of open, chemical-free lawn provides ideal habitat. Bluebirds like to have a lot of open ground with short grass, so if that isn't available nearby, they probably won't use a nest box in your yard.
Can you put a bluebird box on a tree? ›You SHOULD NOT mount bluebird boxes on the sides of trees, fences, or buildings. These are very difficult if not impossible to protect from climbing predators. Also, do NOT hang bluebird boxes.
Do bluebirds return to same nesting box every year? ›Females often build nests in each available hole, but typically only use one of these. Bluebirds may use the same nest for multiple broods.
Should bluebird houses be in sun or shade? ›Place nest boxes in the sunniest, most open area possible, away from your house or deep shade. Bluebirds prefer large expanses of short grass with a clear flight path, ideally facing a field. Try not to place the house too close to feeders.
What color should a bluebird house be? ›You may leave the wood its natural color or paint the bluebird house any dull color; do not use white. Do not use chemical- treated wood and don't add a perch. The inside surface of the front piece should be rough wood so the young birds can cling to it for feeding and to exercise their wings before their first flight.
Do you have to clean out bluebird houses? ›Nest boxes should be cleaned out each year. You will greatly increase the chance of bluebirds (and other desirable species) nesting in your box if it is cleaned annually; this is why our box design comes with a pivoting door.
What is the best wood for a bluebird house? ›Both designs follow the criteria recommended by the North American Bluebird Society (NABS),including the following specifications: Use natural, uncoated wood such as cedar or redwood which are more durable than pine or exterior plywood. Use at least ¾ inch boards. Never include an under-the-hole perch.
When should I put out my bluebird nesting boxes? ›Have your bluebird boxes in place by early spring when the bluebirds are looking for nesting sites. Boxes may also be put up later in the nesting season. In areas where bluebirds are present year round, they may use nestboxes for roosting on cold nights.
What is the best bluebird house design? ›
They found that, when given a choice, eastern bluebirds consistently chose to nest in boxes with oval holes measuring 2 inches tall and 1 3/8 inches wide. (Oval holes can easily be fashioned by drilling two overlapping holes using a 1 3/8-inch drill bit.)
What attracts bluebirds to birdhouse? ›- Install a Bluebird Nesting Box in your back yard. ...
- Place the box in an open area five to six feet off the ground. ...
- Provide food such as meal worms, suet balls or seed consisting all or in part of sunflower chips.
- Water in the form of a small pond or bird bath.
Nest building may take as little as two days, but four to five days are the norm. Other females may stretch nest building out for as long as two weeks. The nest is cup-shaped and truly a work of art. It is typically comprised of pine needles, grass, straw and twigs.
Which direction should a birdhouse face? ›What direction should a birdhouse face? A birdhouse and its entrance hole should face away from prevailing winds. In the United States, it's very common for a birdhouse to face east, which is often faced away from the prevailing wind and the strong afternoon sun.
What other birds will nest in a bluebird house? ›Other nests sometimes found in bluebird nestboxes (depending on the area) include those of Ash-throated Flycatchers, Bewick's Wrens, Carolina Wrens, Eurasian Tree Sparrows, Great Crested Flycatchers, House Finches, nuthatches, titmice, and Prothonotary Warblers.
Do squirrels bother bluebird boxes? ›Raccoons and Red Squirrels
They are intelligent and are good climbers; they can reach into a nest box hole and remove its contents. Red squirrels can enlarge the hole of the bluebird house and even take up residence if able to get inside.
Mounting your box on a smooth round pipe will greatly reduce the chance of a loss to a predator. Any other preventative measures taken will provide added protection. The easiest way to mount a bluebird box would be to nail it to a wooden fence post or to a tree.
Do bluebirds sleep in their nest at night? ›She usually stays on the nest at night. While they may sit on eggs occasionally during the egg laying period, "full-time" regular incubation doesn't start until all eggs are laid. They may wait about a week if weather is still cold.
What is the lifespan of a bluebird? ›Eastern bluebirds can live up to 6 to 10 years. The oldest known wild individual lived 10 years and 5 months. However, most mortality occurs in the first year of life, making average lifespans much shorter than this.
Where do bluebirds go for the winter? ›Bluebirds leave breeding grounds in the north of their range to winter in the southeastern U.S. or Mexico. Populations in the northern part of their range are entirely migratory, spending winters in the southeastern United States or Mexico. Some fly as far as 2,000 miles between western Manitoba and Texas.
What should I mount my bluebird house on? ›
Bluebird houses can be mounted on a metal pipe/pole using pipe clamps (our preferred method). These materials can typically be found in the plumbing section of the local hardware, plumbing, or fencing store. The pipe clamps should be attached above and below the nesting chamber of the house as shown.
How hot is too hot for bluebird house? ›Bluebird eggs and nestlings cannot survive temperatures exceeding 107 °F (41° C) (Conley Black). Prolonged excessive heat can severely impact nestling health due to dehydration and heat stress.
Do bluebirds use houses in winter? ›In winter, a few species of songbirds—the ones that nest in tree cavities or birdhouses in spring—will also use roost boxes to stay warm. Among them: bluebirds, chickadees, titmice, screech owls and some woodpeckers.
How do I keep sparrows out of my bluebird house? ›Wrap some wire loosely around the opening of the box that allows the bluebirds entrance but frightens or confuses the house sparrows.
Will bluebirds reuse the same nest? ›Bluebirds do not remove old nesting material, rather they simply build over an existing nest. If you do not clean out your nest box, it may become filled to the brim with old nesting material. This can potentially leave the new nest dangerously close to the entrance hole, where predators can easily reach it.
Should I remove old nest from bluebird box? ›It's a good idea to clean out your nest box once the young birds have fledged. Photo of Mountain Bluebird eggs by Anne Elliott via Birdshare. You can definitely clean out a nest box after the fledglings leave. NestWatch suggests cleaning out nest boxes or birdhouses at the end of the breeding season.
What color should you not paint a birdhouse? ›Gray, dull green, tan, or brown, are colors that make bird houses or bird feeders less visible to predators because they blend in best with natural surroundings. Avoid metallic or fluorescent colors as they tend to be so bright, they offer no cover from predators.
Can you nail a bluebird house to a tree? ›Do not nail a birdhouse to a tree. Nails can cause damage, and over time could introduce wood-decay fungi that will rot the tree. Do not hang a birdhouse on a branch using a tightly wound string, cord or sling.
How deep should a bluebird house be? ›Bluebirds prefer a house that has an entry hole of 1 1/2 inches for eastern and western species and 1 9/16 inches wherever mountain bluebirds may be. The floor should be between 4 1/2 to 5 1/2 inches square and the floor should be 5 to 8 inches below the entry hole.
Should you put anything in a bird nesting box? ›Most birds will collect their own nesting material, but you can help them out by providing additional bits. A few shredded pieces of paper or cotton wool in the bottom of the nest box will give them a head start.
What is blue birds favorite food? ›
Hulled Sunflower is birds' favorite food but without the mess of shell debris. Get more birds for your bucks by offering sunflower seeds without their shells. No shells means no mess under your feeder.
Where do you put mealworms for bluebirds? ›Once they become familiar with the routine, the mealworms should be placed inside the feeder. The location of the feeder can also be varied. Initially one can place the feeder close (~25 feet) to the nestbox. Then incrementally move it farther away (to ~100 feet) as the bluebirds become familiar with it.
How long do bluebirds stay in a birdhouse? ›Baby eastern bluebirds begin to leave the nest as early as day 16 and continue until day 22. Most young bluebirds leave the nest between days 18 and 22 (88%). Nestlings do not leave the nest before day 16.
Why do bluebirds build a nest then abandon it? ›In some cases, birds are known to seek out areas with predators for nesting due to their suppression of other predatory species. Eggs and nestlings may be abandoned for other reasons, such as inadequate food, poor weather, or the death of the parent(s).
How many times do bluebirds nest a year? ›Young leave the nest at about 18-19 days on average. 2 broods per year, sometimes 3.
Do bluebirds mate for life? ›Most Bluebirds (95%) mate for life, and mated pairs can stay together for as long as they survive. In the event of the death or disappearance of the male or female, the remaining bird replaces it with a new mate.
Should I put anything in my birdhouse? ›Provide woodpeckers, waterfowl, and owls with nest material.
Many cavity-nesting birds will add their own nest material, but the woodpeckers, waterfowl and owls prefer nest boxes with 2-3 inches of dry sawdust or woodchips in the bottom.
Shelter: Thicket-like shelter that includes evergreen trees and a variety of native plants will be most attractive to nesting birds. They will use twigs, plant down, mosses, and bits of leaves for nesting material, and will hide in brush piles and bird-friendly shrubs to stay safe from predators and poor weather.
Where do I position my bird box? ›Choosing the location
Unless there are trees or buildings which shade the box during the day, face the box between north and east, thus avoiding strong sunlight and the wettest winds. Make sure that the birds have a clear flight path to the nest without any clutter directly in front of the entrance.
Place nest boxes in the sunniest, most open area possible, away from your house or deep shade. Bluebirds prefer large expanses of short grass with a clear flight path, ideally facing a field. Try not to place the house too close to feeders. Make sure it is mounted 5 to 10 feet off the ground.
What do bluebirds like for nesting material? ›
What kind of nest material is being used? Bluebirds will most often use pine straw or fine dry grass. A nest may take hours or longer than a week to complete. Now you will be looking for that first egg.
How soon after building a nest do bluebirds lay eggs? ›The female Bluebird begins laying eggs between 6 and 7 days after the nest is completed. The overall timing of egg-laying throughout the Bluebird's range reflects the timing of nest building. Egg-laying begins during February and March in the warmer southern states and March and April in the northern and colder states.
What time of year do bluebirds nest? ›It could be that in years when the emergence of tree-munching caterpillars is delayed or unseasonably early, it's an advantage to nest out of sync with the rest of the crowd. Generally speaking though, eggs are usually laid throughout April and into early May.
Should bluebird houses be in the shade? ›Bluebirds prefer open grassy areas, fields and no shade. It's best to have a place where high grass and weeds do not grow beneath the nest box. Boxes should be posted five to six feet off the ground, although boxes placed a little higher usually suffice.
Do birds like dryer lint for nesting? ›Birds may also use plastic strips, cellophane, and aluminum foil, but we don't recommend that you offer these materials. Also, don't offer dryer lint. It may seem nice and fluffy, but becomes crumbly after it's rained on and dries.
What month do you clean out bluebird houses? ›You will greatly increase the chance of bluebirds (and other desirable species) nesting in your box if it is cleaned annually; this is why our box design comes with a pivoting door. To give all cavity nesters time to complete their breeding cycle, it is safe to clean boxes between September-February.
Do bluebirds use nest boxes in winter? ›Bluebirds and other cavity nesters often use nest boxes in the winter for nightly roosting. A small group of birds may cluster together for warmth, all in the same box. Our boxes are designed with lots of ventilation so that bluebirds don't “cook” inside the boxes in the summer heat.
Do bluebirds leave their eggs unattended? ›As a general rule, bluebirds abandon their eggs for one of the following reasons: The eggs are unfertilized. One or both adult bluebirds pass away. The eggs overheat.
How high should nesting boxes be off the ground? ›The height of the nest box should be no less than 18 inches from the floor and can be as high as a few feet off the ground. They should not be at the same height as your roosting bars, or you may find your hens sleeping in the boxes!
Should you put a bird feeder near a nesting box? ›Avoid placing nest boxes too near to bird feeders and bird baths, as high levels of activity from visiting birds will cause disruption to established nests and may even lead to it being abandoned. Most species of bird are territorial, so having too many nest boxes in one area can cause problems.