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Bluebird.FAQ (revision 3.1.2.)

This FAQ (Frequently Asked Questions) deals with Bluebirds (predominantly Eastern Bluebirds, but I will try to include Western and Mountain Bluebirds as often as possible). Much of this information also pertains to other cavity nesting birds such as Chickadees, Titmice, etc.  Don't be misled this FAQ doesn't answer all the questions you might have about bluebirds.  In fact my intent is to pique your interest, get the basics covered, and to give you information where to go for follow-up information.  For those of you interested there are web pages for other cavity nesters:

Chickadees at http://www.jtan.com/~jack/ckd.html
Purple Martins at http://www.purplemartin.org/

Other web sites with Bluebird FAQ's, Facts & Basic Information

North American Bluebird Society (NABS)
Bluebirds Across Nebraska (BAN)
Prescott Bluebird Recovery Project

This FAQ is available at: http://audubon-omaha.org/bbbox/bbfaq.htm

Probably the most significant part of my web site is The Best Of Bluebird Mailing Lists Classified.  There you will find classified messages posted to the now defunct Bluebird-L mailing lists.


The Bluebird is a member of the thrush family related to the American Robin. The Eastern Bluebird (Sialia sialis) is generally found in the eastern half of North America to the Rocky Mountains. The Mountain Bluebird (Sialia currucoides) is found from the eastern foothills of the Rocky Mountains west to the Pacific coast of the North America. The Western Bluebird (Sialia mexicana) is typically found west of the Rocky Mountains. All three species are blue on the back. The Eastern has a red breast and white belly. The Mountain is slightly larger than the Eastern and does not have the red breast. The Western is similar to the Eastern with the red of the breast spreading around to the back.

Bluebirds are NOT Bluejays, Indigo Buntings, or any other bird species that is blue.


The natural habitat of Bluebirds are open fields, prairies, and meadows with few trees or shrubs. The natural nest location is an old woodpecker hole or rotted (hollow) limb on a tree. The artificial habitat that man has created that is usable by the Bluebird includes brome fields, horse and cattle pastures, cemeteries, golf courses etc. This artificial habitat should be one that does not include the use of pesticides, as they can be harmful to the insect eating birds. Man has taken up the Bluebird cause and has created nest boxes for the Bluebirds on both the natural and artificial habitat areas. Woodland habitat is less favorable to bluebirds, but there are a number of other species that would make use of a Bluebird nest box in such habitat. These would include House Wrens, Chickadees, Great-Crested Flycatcher, Nuthatches, Titmice. Placing a Bluebird box in woodland habitat is not necessarily bad but, Bluebirds nesting there would probably be usurped by other birds (most probably house wrens).  Where house wrens or flying squirrels are present in your area then these two species may take over use of your bluebird nestboxes in mostly wooded areas. Other wrens are not considered a problem.


A loose definition of a Bluebird trail is a single Bluebird nest box, monitored for the removal of undesirable birds (House sparrows). Many trails are much longer, some consisting of hundreds of boxes. A more typical trail might consist of six to thirty boxes. Naturally the trail should be in the best Bluebird habitat available in the area.


There are many good Bluebird nest box designs. Such as Peterson's, Gilbertson's, NABS, slot box, and the many variations of these boxes. What constitutes a good box is primarily a box that the bluebird's will use, you can monitor, and the predators can't get into.

The entrance hole for Eastern and Western Bluebirds should be one and one-half inches in diameter (the Peterson Box hole size is an oval (1&3/8" x 2&1/4") and Mountain Bluebirds should have a one and nine-sixteenths inch hole or (Peterson, 1&1/2" x 2 1/4").  Not to confuse the issue but a well respected bluebirder, Keith Kridler, makes the following comments on the use of the oval Peterson entrance: "Well the Peterson Oval entrance 1&3/8" wide is a KNOWN AND PROVEN entrance that allows starlings from all over North America to "easily enter and leave nestboxes." The last is a quote from Kevin Berner's article! For the last 70 years bluebird conservationists have fought to educate the public to use an entrance hole to "positively exclude ALL starlings""

The box material should be untreated wood such as cedar or redwood. It is acceptable to use pine but under no circumstances should the box be painted on the inside. Do not use the cardboard boxes that some of the schools have allowed students to paint as Bluebird boxes.

Ventilation is also another key ingredient in good box design. In colder climates the ventilation holes can be plugged until warm weather arrives.


There are many reputable dealers that build good nest boxes. The designers of boxes themselves (such as Steve Gilbertson) sell boxes that they build. State Bluebird organizations often sell nest boxes or recommend nest box manufacturers. Garden centers, nurseries, and nature stores sell boxes but be careful, often their boxes are of inferior design (they can't be opened for cleaning, have a perch, entrance hole wrong size, etc). Nature store boxes also tend to be expensive when compared to boxes from other sources.


Ideally the nest box should be placed on a metal post, such as a fence post or electrical conduit that is not part of a fence line. The boxes should be 50 feet from nearby bushes and trees and 200 feet if house wrens are a problem. The nest boxes should be placed about 200 to 300 feet apart. I generally place mine such that the view from one box to the next is obscured by distance, an obstruction (such as a hill, tree, etc), or other barrier. If Tree Swallows are using your boxes then the boxes should be paired (distance between boxes (15 to 22')), then spaced 300 feet to next pair.

The nest box should be placed no higher than what is convenient to monitor. Bluebirds will actually tolerate boxes mounted much higher (twenty feet) or as low as three feet. I recommend five feet as this is a height that most people can monitor easily (The real experts will suggest five feet as a minimum).

The opening of the nest box should be directed away from prevailing winds to prevent rain from being blown into the box opening. The birds themselves don't mind which direction the opening faces, but if the fledglings are exposed to moisture and cold this can cause hypothermia. When specific orientation is an option orient the box opening away from the hottest exposure to the sun away from the nest box opening. Although any box orientation might be used reports indicate the most often selected and most successful box has the hole facing either east or slightly northeast. The boxes can placed around a field in a circle to make a monitoring circle.


Boxes should be in place (if taken down in the winter) or cleaned and unplugged (if plugged to prevent mice or house sparrows from roosting in the box) early in the year (late February or early March).

Box monitoring can be started slowly in the early part of the season (every other week is sufficient). When nest building begins the boxes should be monitored on a weekly basis as a minimum, and no more often than twice a week. Monitor weekly only until nestlings are 12-13 days, then after they fledge remove old nesting material then resume weekly monitoring. Weekly monitoring should continue until the season is over (usually mid August). The box should be checked and closed as quickly as possible. You should spend as little time at the box as necessary to prevent scaring off any possible nesting Bluebirds.  Western Bluebirds fledge at an average of 21 days. 

When checking the box all House Sparrow nests should be removed along with eggs. The House Sparrow eggs should be destroyed or can be taken to a local nature center for feeding to snakes. If box monitoring is done on a weekly basis, house sparrows may be able to build a nest and lay eggs but they will have insufficient time to hatch the eggs. Many bluebirders trap House Sparrows but that presents a problem for some in that the captured birds must be destroyed.

There will be other nests found in the nest boxes, typically these will be from House Wrens, Nuthatches, Great-Crested Flycatchers, Chickadees, Titmice and other cavity nesting birds. These other species with the exception of the House Wren will not cause trouble on your Bluebird trail. It is a violation of Federal law to disturb all of these species while nesting However, many bluebirders will remove dummy House Wren nests (Boxes filled to the top with sticks). Removing wren sticks placed by the male is legal; the nest is the cup the female puts on top of the sticks, and that of course is protected by federal and state laws. Also house wrens are a very territorial bird and can cause considerable problems on a Bluebird trail.

Old Bluebird nests should be removed after the babies have fledged. I have found that failing to remove the nests will result in the nest being invaded by ants after the birds have fledged. There is a new school of thought that the old nest should be left. I feel that might be acceptable for the last brood of the season but not until then. There are studies that indicate Bluebirds are predisposed to use a box with an old nest in it.


It is actually very easy to determine a Bluebird nest. Bluebirds have a very neat nest made from fine grasses (occasionally pine needles) in a nice cup shape. Typically there will be no seed heads, cigarette butts, strings, sticks, or other junk in a Bluebird nest. Occasionally there will be some cattle or horse hair in the Bluebird nest. Bluebirds keep the nest relatively neat by removing fecal sacs and other debris. Dick Purvis who is a well know bluebirder informs me that "Western bluebirds primarily make their nests out of dry grass. However, they will use anything conveniently near that is equivalent. Many of mine make their nest entirely of conifer needles. They may be influenced by the fact that some of the conifers here have needles that are very long up to 6 to 8 inches. Bluebirds whose nestboxes are in cottonwood trees use the inner bark of the cottonwood for their nest. This is a soft thin material similar to grass. At Easter time, many of my bluebirds in public parks make their entire nest out of green Easter basket confetti! In general, most nests have a couple of small feathers in them. They usually have a piece or two of cellophane in the cup. They will also try to use artificial items like twine or monofilament fish line. I have found a few dead birds, both adults and young, tangled in nest material like this."

House Wren nests are mainly sticks, about two to three inches longs. They may line the very top of the nest with grass or hair. Often House Wrens will bring spider egg sacs into the nest.

House Sparrows nests are made from grass, but are very loosely made and will include a collection of a variety of trash, including: cigarette butts, string, feathers, and just about anything else they can pick up. One big clue is seed heads in the nest. The nest usually has no bottom and has a domed top.

Chickadee nests are usually made from moss and lined with hair or down, in general appear to be a quite comfortable place to be born.

Mice also use nest boxes and are more a threat to the monitor than to the bluebirds. There is a virus that can be acquired through mice droppings and therefore caution should be exercised when cleaning out a mouse nest. The mouse nest will usually consist of milkweed pods. Always stand up wind of the box when removing these nest and do so with a stick or brush (not with your hand).

As stated before other cavity nesting birds will use Bluebird nest boxes but none of these birds are a threat to bluebirds. In fact if another bird is using the nest box consider yourself lucky to be able to enjoy another species. Other species using your nest box might be an indication that the area you selected for this nest box is inappropriate for Bluebirds (NOTE: I'm not suggesting you remove this box, just that this is not Bluebird habitat).


A record of what was observed at the nest box should be maintained for each box on the trail. This information should include dates, number of eggs laid, eggs hatched, birds fledged. This information is important to many Bluebird organizations including your state's Bluebird organization and the North American Bluebird Society. The organizations have forms to be filled out and sent in at the end of the Bluebird season. These organizations use this information to obtain trends on the breeding success of Bluebirds in their areas. Also it can help to determine which boxes work the best in certain areas. These records provide you with information as to what boxes are producing and which boxes are proving to be a problem with predators. At the end of the season it is comforting to know how many Bluebirds fledged from your boxes.


If you are using proper Bluebird nest boxes that will eliminate starlings from usurping Bluebirds from your nest boxes. That only eliminates one of the many predators. The two biggest predators are House Sparrows and House Wrens. These birds will usurp nest boxes, they have been known to break eggs, kill babies and adults, build nest over Bluebird nest, etc. In recent years much concern has been expressed about the effects of House Wrens on other nesting birds. House Wrens, unlike most other song birds, are territorial toward ALL other species, not just their own. Other predators include Bull snakes, Blowflies, ants, cats, raccoons, squirrels, etc. There are predator guards available to prevent some predation, other times such as with Blowflies and ants a specialized insecticide is needed like a natural pyrethrum insecticide IF and only IF blowflies are there in huge numbers and even then better to either lift up the nest, gently shake and brush out larva or make a new nest of fresh dry grass and replace the old one. I have known bluebirders to carry an old bluebird nest to be used in the replacement of a infested or extremely wet nest. CAUTION: tampering with the nest or possession of an old nest is technically illegal (yes, even by a bluebird trail monitor). Extreme caution is urged when using insecticides please use sparingly as they can prove harmful to the fledglings, adults, and bluebird monitors.


Bluebirds will come to your feeder if you provide the right kind of food. The Bluebird food of choice is insects. You can provide this food by giving them mealworms. Mealworms can be acquired from pet supply stores, nature stores, and by mail order. Occasionally Bluebirds will come to feeders for seed, but this is usually done when insects are in short supply.  Much like the other members of the Thrush family they will also eat small berries such as cranberries.


In the winter the Southern states play host to a great number of Bluebirds that have migrated from the Northern states and Canada.  It seems to be more common for Bluebirds to over winter in the North.  The reasons are most likely very numerous.  Speculation includes improved numbers have caused more birds to over winter in their native nesting territories giving them an advantage when spring arrives to be first in the area.  This gives the males a better chance of getting a nest box in the best habitat.  This over wintering most likely is influenced by a greater number of humans providing the necessary ingredients to make survival possible.  That would include roost boxes and food.  It is probable that some of these over wintering birds will not survive the winter but just as likely many migrating birds do not survive the migration process.  It is likely that both migration and over wintering should help produce a more durable species in the long run.  Humans played a part in the decline of natural habitat for the birds and it is only logical that they provide an artificial habitat as a replacement.


  1. There are a number of places to go for assistance for Bluebird problems and questions. The first thing I recommend is to get a good Bluebird book. The one I recommend is "Bluebird Trails-A Guide To Success" by Dorene Scriven. This was written by a bluebirder for bluebirders. It has nest descriptions, box types and plans, monitoring forms. In other words all the help you could ask for. Other good Bluebird books are "The Bluebird-How You Can Help It Fight for Survival" by Lawrence Zeleny of NABS and "Enjoying Bluebirds More" by Julie Zickefoose (published by Bird Watcher's Digest). Next find the name and address of your state Bluebird organization (see list at end of this FAQ). The state organization usually has people in your area that can help with box type selection for your area, specific predator suggestions, workshops, a newsletter, and often a state conference to discuss the many bluebirder related concerns. These groups are usually supported through donations or through your state non-game wildlife program. Another worthwhile Bluebird organization is The North American Bluebird Society (NABS). This organization exists on the dues and donations of it's members. It is devoted "...to increase the populations of the three species of Bluebirds on this continent." NABS publishes a quarterly journal (Bluebird), offers grants for Bluebird research projects, publishes results of Bluebird research, has a nationwide Bluebird Conference, etc.
  2. Ask questions, all the bluebirders I've ever met are always very happy to share their knowledge and Bluebird stories with anyone willing to listen. For bluebirders, Bluebirds become part of their life, almost a part of their family - let them show you their kids.
  3. The internet is gaining the attention of bluebirders.  (I had this in the FAQ in 1995, now the internet is an invaluable resource).

The following  individuals, books, and materials were useful to me in creating this FAQ:

Bluebird Trails-A Guide to Success by Dorene Scriven
Bluebirds Across Nebraska Information Booklet
Siala-A Quarterly Journal of The North American Bluebird Society
Enjoying Bluebirds More by Julie Zickefoose
Bluebirds Across Nebraska-Quarterly Newsletter
Minnesota Bluebird Recovery Program-Quarterly Newsletter
Dorene Scriven deserves more credit for this FAQ than I can put in words, her book and critique have proved invaluable 

The following individuals have also offered ideas for the FAQ for which I am grateful:

Keith Kridler
Dick Purvis
Linda Violett This is the original Bluebird FAQ on the Internet.  This FAQ was on the internet before I had a web site.  In fact I think there was only one Bluebird web site on the internet at the time and that was  Phil Wagner of Minnesota's.  Things have changed a lot for those who bluebird the internet.  There is more involvement by bluebirders at every level.  There are times when they don't agree, but you can be sure that the goal of every bluebirder is to help all who choose to bluebird to have the best experience possible, and for that experience to aid not just bluebirds but for every native cavity nester in North America.

I am solely responsible for the content of this FAQ. It has been prepared for the use and enjoyment of new and experienced bluebirders everywhere.
Please send all comments to me via:
E-mail at bluebirdbox@cox.net (please when sending me mail include a subject such as bluebirds or other so I don't throw away your mail)

Snail Mail to
Jim McLochlin
9521 Burdette Cir
Omaha, NE 68134

I grant permission for this FAQ to be posted, printed, etc as long as the entire document is kept intact. If quoting from this FAQ is desired please give me credit.


Please E-mail me at bluebirdbox@cox.net and specify a subject such as bluebirds.

date of last change 01/20/15 Web space provided by the Audubon Society of Omaha.