Bluebird Frequently Asked Questions

Q: Where are bluebirds found?
A: Three species grace North America. Eastern Bluebirds are generally found in the eastern half of North America across the Great Plains to the Rocky Mountains. Western bluebirds are typically found west of the Rocky Mountains, mainly in the far western states and provinces. The Mountain Bluebird is normally found at the highest elevations from the Northern Rockies in Canada to Arizona. Although the range of the Mountain bluebird overlaps with the other two species, it occurs mainly in the western states and Canadian provinces. Conversely, the Mountain bluebird range has recently overlapped the Eastern Bluebird, with sightings as far east as Minnesota, Iowa, and Kansas.

Q: Do bluebirds have special nesting requirements?
A: Bluebirds require a cavity, or hole, within which to nest. Since they are unable to excavate these cavities themselves, they are referred to as secondary cavity nesters. Woodpeckers are primary cavity nesters, and in natural habitats bluebirds will search out old woodpecker cavities to construct their nests.
Woodpecker cavities can be replicated by a bird house or nest box. Bluebirds do not distinguish between the 'real thing' and the 'fake'. They will readily adapt a nest box as their home. This acceptance of artificial housing has led to the development of bluebird trails by thousands of people all across North America. Bluebirders can be credited with establishing the most enthusiastic and widespread conservation movement on the continent.

Q: How do I identify a bluebird nest?
A: The female bluebird constructs a tidy nest from materials that are readily available near the nest site. These nests are usually composed of dry grasses, pine needles, or strips of bark. The nest is usually not lined. with soft materials. The presence of bluebird eggs will confirm that a pair of bluebirds has taken up residence.
It can be difficult to distinguish between bluebird and house (English) sparrow nests in the early stages of construction. The completed nests, however are quite different. House sparrow nests are built up much higher on the sides and are often domed over the top. These nests are composed of a variety of materials from small twigs, grass, leaves, and quite often contain man-made products such as paper or string. The common house wren builds a very identifiable nest from the beginning of construction. House wrens build their nest almost entirely of small sticks, using enough to fill the entire box. Many birding books show photographs of the nests of various species of cavity-nesting birds

Q: Will bluebirds nest in a box near a human dwelling?
A: Yes. In fact several bluebird landlords have reported limited success at attracting bluebirds until the box was moved closer to a house or patio area. Bluebirds, like Purple Martins, are very compatible with humans. The problem with trying to entice bluebirds to nest close to human dwellings is that house sparrows also commonly nest around buildings and sheds, and are likely to aggressively compete for the nest box. Care must be taken to ensure house sparrows do not use nest boxes.

Q: Can I attract bluebirds inside the cities or towns?
Generally not. Bluebirds prefer wide open spaces found in rural areas and around the perimeter of small urban areas. They have been know to nest on the fringes of towns and cities, especially if they were nesting in those areas prior to development. Predation by cats and competition from house sparrows is a serious problem in large developed areas such as cities and towns.

Q: Will bluebirds come to my feeders?
A: During the nesting season, many bluebird trail operators, as well as those that maintain only one or two nest boxes, attract bluebirds to feeding stations where mealworms are offered. Mealworms are generally available at birding stores. You may also purchase them by mail. It is simple to raise your own mealworms at home. (Refer to NABS information sheet on "Raising Mealworms'). Some bluebird specialty food is available in wild bird specialty stores. There are also some foods you can make at home. It is often necessary to initially attract bluebirds to the artificial foods by offering mealworms. Where they over-winter, bluebirds occasional come to feeders for seeds during foul weather. This generally takes place when insects, which are their main food source, or berries are in short supply.

Q: Do bluebirds migrate?
A: Yes. They are known as "partial migrants". In the northern sections of their range, all bluebirds migrate to more southerly latitudes for the winter. In the central and southern sections of their range, they have less established migratory patterns. It is believed that some winter migration is in response to local weather conditions. Yet even in very cold wintery weather, some bluebirds do not migrate at all. They tend to group together for feeding and protection during the winter months. While some bluebirds that remain do survive the inclement conditions, many perish.

Q: Are Spring snowstorms hazardous to nesting adult bluebirds?
A: During the nesting season, a bluebirds diet consists primarily of insects. In the fall and winter, they supplement, or completely switch their diet to berries and other fruits. Food shortages often occur in the spring when the supply of berries and fruits have been exhausted, and insects are not yet active. Natural food can be supplemented with mealworms, raisins and other dried fruits, chopped nut meats (unsalted), suet and specialty feeds. Offer food on an elevated platform. A picnic table or porch railing will work well. Since bluebirds are not a seed eaters, they will not benefit fi7om the provisions of standard wild bird mixes for them. There have been reports, although rare, of foraging on hulled sunflower meats.

Q: When should I have my Bluebird boxes ready for the nesting season?
A: Southern states -by February 1st; Northern and Central states -by March 1st; Canada by March 15th. This does not mean that houses cannot be put up prior to or after these dates.. These are the dates for receiving full season results. Bluebirds will raise one brood in the northern parts, as many as three broods in the south.

Q: What habitats do bluebirds prefer to nest in?
A: Bluebirds prefer to nest in open fields, prairies, and meadows that contain scattered trees and shrubs. Nest boxes placed around livestock pastures, cemeteries, and other open spaces in rural settings. Successful bluebird trails have been established around pesticide-free golf courses. Woodland habitats are less favorable to bluebirds. There are a number a species, however , that will use bluebird boxes placed in wooded areas. These include House Wrens, Chickadees, Flycatchers, Nuthatches. Swallows, both the Tree and Violet/Green, are common in bluebird nest boxes.

Q: Can you. attract bluebirds to a box located where no activity has been spotted in years?
A: Yes, assuming the bluebird box has been located 'in suitable bluebird habitat. Other than that, there is nothing you can do but to keep the nest box free from being inhabited by house (English) sparrows. It is surprising how often bluebirds show up at a properly-located nest box, even if bluebirds have not been spotted in the area for years. In the early spring, these birds are suspected of searching far and wide for suitable places to nest. Loss of natural habitats and the proliferation of the house sparrow population across North America has made nesting sites for many native cavity nesting birds scarce. You may also want to try planting trees and shrubs that are attractive to bluebirds.

Q: Where and how should I locate a bluebird nest box?
Ideally, nest boxes should be mounted on a smooth metal pole. Such as a fence post, pipe, or electrical conduit. The boxes should be at least 50 feet from nearby trees and shrubs, and 200 feet if house wrens are likely to compete for the nest site. Bluebird boxes should be placed at 300-foot intervals or greater. If possible, obscure the nest boxes from each other by distance, a small hill, an obstruction or other barrier. If tree swallows are using your boxes another bluebird nest box may be paired with the other and spaced at least 10 to 25 feet apart. The nest box should be no higher than is convenient to monitor and maintain the box. Bluebirds will tolerate nest boxes mounted as high as 15 feet or as low as 3 feet above the ground. Boxes that are mounted less than 4 to 5 feet above the ground will become more accessible to ground dwelling predators.

The opening of the nest box should be directed away from prevailing winds to prevent rain from blowing in. The direction of the opening does not affect the use of the box, but young birds exposed to moisture can suffer hypothermia, which is often fatal. When possible, position the opening away from direct sun exposure. Also facing the entrance toward a tree or bush allows for a safe perch when the young have fledged the nest. Records indicate the most often used boxes have the opening facing either east or slightly northeast. It is also wise to position the opening away from or parallel roads and highways to reduce conflict with traffic as they leave the box.

Q: Is it important to monitor bluebird boxes and keep records of their activities?
A: Monitoring is the very heart of the bluebirding experience. The monitoring of bluebird nest boxes is very important, whether you have just one or two boxes, or a trail consisting of many. By monitoring the nest boxes on a weekly basis, you will be able to keep track of all that goes on in and around your boxes. You will also be able to make repairs to boxes as needed. Monitoring on a regular basis will also enable you to reduce potential problems with competitors of the box, as well as parasites and predators.

In addition to ensuring that your bluebird trail is successful, monitoring enables you to keep records of bluebird productivity. By keeping records, you will be able to determine which boxes are successful for bluebirds, and which ones may have problems with predators or competitors. You will also get satisfaction from knowing how many birds successful fledged from the boxes you are maintaining. The data you collect are also used by bluebird organizations and researchers to track bluebird population and movements. Most states and provinces have reporting forms which can be filled out at the end of the nesting season. If possible obtain a copy of the form prior to the nesting season so you are familiar with the specific information required. If no state or provincial organization has yet been formed in your area, contact the North American Bluebird Society for a copy of their nest data form. Basic information that should be collected on every bluebird trail includes: 1) Date of each box inspection, 2) number of eggs laid, 3) number of young hatched, 4) number of young fledged. Additional useful data includes: style of nest box, pairing information, date of first egg, hatching dates, fledging dates, type of habitat, white eggs, sex ratio, etc... It is useful to record unusual behavior and other interesting observations.

Q: How often should bluebird boxes be inspected?
A: Under normal circumstances, a weekly inspection is sufficient. However other factors may require more frequent monitoring. During the egg laying period, which generally takes place in the early morning and lasts 5 days, care should be taken so as not to frighten the female. Boxes should not be opened after the nestlings are 12 to 13 days old. This may frighten them and cause the young to fledged prematurely. After the 13th day, it is best to observe the box at a distance until you are certain all the nestlings have fledged.

Q: What bluebird predators may I expect to encounter?
A: Bluebird predators 'include snakes, cats, and raccoons, which are able to climb the post to access the nest, and raptors (birds of prey) which may take the fledglings as they leave the nest. There are precautions that can be taken to reduce the problem of predation at the nest box. These precautions include proper mounting and placement, and frequent monitoring, (Refer to NABS information sheet on "Predator Control").

For insect infestation, such as blowflies and ants, you may gently raise the nest and brush the insects and their larva out of the box. Gently tap the nest to dislodge others. Check the nestlings for any larva that may be attached to them also and remove. In the event of a serious blowfly infestation, replace the old nest with a new one made from fresh dried grasses. Some bluebird enthusiasts go as far as to carry an old bluebird nest in their pack while monitoring boxes to replace heavily infested or wet nests.
The two most common and serious avian competitors are house (English) sparrows and the house wren. House Sparrows were introduced into North America in 1850. They are considered a pest species, so are not protected by Federal Laws. House Sparrows are very intelligent, aggressive and persistent. They will kill adult and nestling bluebirds in the box, then build their nests over the corpses. Another introduced cavity nester, the European Starling, poses a threat to bluebirds in natural areas, but can be excluded from bluebird boxes as long as the entrance is no larger than "1 9/16 inches. House wrens are native to North America and fall under Federal protection. Both have been know to puncture bluebird eggs, kill the young birds and adults. The sparrow will then build its nest on top the bluebird nest. Wrens have been know to not only puncture eggs or toss them out of the nest, but remove nestlings and drop them to the ground. Competition from house wrens may be reduced if the nest boxes are located at least 200 feet from trees, shrubs, briars ~) and other woody areas. (Refer to the NABS information sheet on "house Sparrow Control"). The European starling can pose another serious threat to bluebirds. However if the entrance hole is no larger than 1 9/16 then you can prevent their access.

Q: Can a bluebird box be made house sparrow proof?.
A: Although extensive field testing has been done by bluebirders across North America, no one has yet to discover a way to prevent House Sparrows from using bluebird boxes. To reduce the problem of House Sparrow use, locate bluebird nest boxes away farm building, areas where animals and livestock are fed, out buildings such as sheds, and away from towns. Some trail operators have found mounting the box 4 to 5 feet above the ground may also discourage the house sparrow. However again we must mention that nest boxes mounted that low become a risk by ground predators. Thin-wall PVC boxes appear to be less attractive to the house sparrow, especially if they are paired with a standard wooden bluebird box. It is also critically important to remove house sparrow nests from bluebird boxes. There are several styles of live traps that can be used to help reduce local house sparrow populations. One design allows to trap the sparrow from the nest box itself. Traps should be checked regularly to release the inadvertent trapping of other birds. it is highly recommended that house sparrows that are trapped not be released back into the wild. (Refer to NABS information sheet on "Controlling House Sparrows").

Q: How do you protect bluebirds from the family cat?
A: Cats, both domestic and feral, pose an serious threat to our wild bird population. A recent study in Wisconsin estimates that roaming cats kill more than 800 million song birds a year in the United States alone. The American Birding Conservancy, The National Humane Society, and The National Wildlife Federation recommend that family cats be kept indoors for their own safety and health, as well as the safety of our wild birds. Feral cats, (cats with no owners) pose a serious problem not only to wildlife, but to humans as well. Feral cats should be eliminated for health and safety reasons. Cats will kill whether or not they are hungry. Even cats that have been declawed possess the ability to kill birds and wildlife. A cat's urge to kill is independent of their urge to eat. They kill because it is part of their instinctive nature as hunters. Bluebird nesting boxes may be protected from cats by placing a funnel shaped baffle, wide smooth collars made of sheet metal, or a metal stove pipe mounted over the post below the nest box. Since cats have good jumping ability it is suggested the box be no lower than 6 feet off the ground. These same protective measures may also reduce predation by raccoons. For more information on the impact of cats on birds and wildlife, contact: The American Birding Conservancy, 1250 24th Street N.W., Suite 400, Washington, DC 20037. Request the kit entitled, "Cats Indoors".

Q: What if house wrens pose a constant problem by building nests in bluebird boxes?
A: Bluebirds usually start their nesting activities two to three weeks before house wrens begin theirs. This give the bluebirds some advantage in locating nesting sites. Once the house wrens arrive in their nesting territories, they will sometimes enter a bluebird nest box, puncture bluebird eggs and may even eject the eggs from the nest. They have been know to remove nestlings from the box as well and simply drop them to the ground. To minimize house wren competition, locate the nest box in open areas, as far as possible from stands of trees, shrubs, and other underbrush. Although it is unlawful to remove a completed House Wren nest, you may remove the male wren's uncompleted or dummy nest.

Q: Should the bluebird nest be removed after each fledging?
A: Yes. Remove the nest, clean the box and make any necessary repairs.

Q: Bluebirds arrive in the morning, perch on the nest boxes, then leave showing little interest in nesting. Why?
A: Since bluebirds are very territorial , boxes should never be spaced closer than 100 yards, the length of a football field. With a trail consisting of several nesting boxes located closer than 100 yards apart the bluebirds are probably using them as perches to look for insects. If this happens on a regular basis there is a good chance they are nesting nearby. Check to make certain your nest boxes meet the requirements for bluebirds and that they are spaced adequately apart. (Refer to the NABS informational sheet on "Getting Started with Bluebirds").

Q: Do Bluebird fledglings remain in the vicinity of the nest box once they have fledged?
A: The movement of young bluebirds after they leave the nest is not well known or always predictable. It is thought they usually remain for a time in the general vicinity, but not necessarily in the immediate vicinity of their natal box. Since suitable nesting sites for bluebirds are scarce, bluebirds will often choose a nesting sites where the food supply is not optimal. Thus, adult birds may have to travel some distance to obtain food for the nestlings. As soon as the young birds can fly, it appears that the parent birds encourage them to move closer to a better supply of food. This simplifies the task of feeding them and, at the same time, explains why the young birds appear to disappear from the nest site . It also permits the adult birds to begin construction of another nest. If mealworms are supplied this enhances the chance the young birds will remain in the immediate area even after the adult bird ceases providing them food. Mountain Bluebirds appear to abandon the nesting area altogether after the young have fledged, but then seem to regroup in the fall prior to migration.

Q: How important are drain holes and ventilation openings in bluebird boxes?
A: Some ventilation is important as nest boxes should be placed in open areas and away from trees that would normally >provide shade, except where such shade is provided by a single tree. Ventilation holes or slots should be located on both sides of the box just below the roof Boxes with large overhangs, such as the Peterson Bluebird Box, do provide adequate protection from rain, and as such, do not require drain holes. Other nest boxes lacking the extended overhang should have the four comers of the floor cut off. This produces triangular drains at each of them. This allows drainage for any water that accumulates inside the box, as well as moisture from condensation. The floor of the nest box should also be recessed 1/4 inch above the four sides to prevent the floor from absorbing water.

Q: Is an exterior perch necessary on a bluebird nesting box?
A: Since bluebirds have the ability to cling, they are adapted to enter both tree cavities and nest boxes without the aid of a perch. House sparrows do not have the ability to cling, and as such a perch will assist their ability to enter a nesting cavity. It also permits easier access for other predators. It is recommended to eliminate perches not only from bluebird boxes, but also from all nesting boxes for primary and secondary cavity nesters.

Q: Are raccoon guards effective on bluebird boxes?
A: The preferred method to keep raccoons from climbing the pole in the first place. Smooth metal poles can be sprayed with silicone making them to slippery to scale. You may also rub the pole with steel wool and then apply "carnauba" wax producing the same results. A quality grease rubbed on the pole should last the entire nesting season, but periodic inspections are recommended, and the pole cleaned and re-greased if necessary.

The effectiveness of the extended wood block predator guard at the entrance hole is not completely is still undetermined. It is far from fool proof and may make it more difficult for bluebirds to access the box. The "Noel" predator guard with the adapter works well. Do not install this guard until after the first egg is laid. The exception is if the bluebirds have used the box previously with the guard in place.

Q: What if wasps try to establish a nest in my bluebird box?
A: If at all possible remove the nest. If the wasp nest is discovered in the early stages of construction there will only be a few wasps on it making eviction less hazardous. Later into the season removal is more difficult as the nest becomes larger with many more wasps. Always check under the roof and at the bottom of the nest box when monitoring your bluebird housing. Hard soap or vaseline rubbed on these surfaces will help prevent wasps from attaching their combs.

Q: Do bluebirds have a sense of smell?
A: Bluebirds and other passerines have a very poor sense of smell and taste compared to mammals including man. This is often the reason why it is permissible to handle young birds while maintaining nests, or placing a nestling back into the nest if they have fallen out. The adult birds cannot detect the scent of the human handling their young, as well as the fact man and wild birds interact much more readily than most other wildlife. Birds do however have excellent hearing and superb eye sight

Q: What are some berry producing plants, attractive to bluebirds, whose fruit lasts through the winter?
A: Among the best are the American holly, Mountain ash, Staghorn sumac, pyracantha, bittersweet, red choke berry, and various hawthorns. Multiflora rose is also one of the best, but this shrub can become a serious nuisance because of its invasive nature. There are many books available that deal with landscaping for wildlife. Plant species native to your area will insure a hearty and long lasting yield year after year. Your local nursery may be able to help if he is accustomed to plantings for attracting wildlife. Check with your state forester, game commission, or local natural resource district to see if they have any publications on this subject.