Bluebird FAQ Sheet

Bluebird FAQ Sheet

The following Frequently Asked Questions are used by permission from the North American Bluebird Society (NABS).

Q1: I would like to mount a Bluebird box. How should I begin?

Once you’ve caught the Bluebird bug, it’s difficult to resist these beautiful creatures. However, one must begin this undertaking with a clear understanding that these special birds require special care and attention from you. Below are several considerations you should first review in order to determine whether mounting a Bluebird box is a good idea:

A) Since Bluebirds eat insects that live on the ground during warm weather, they require immediate access to open areas so they may hunt for food as close to the nest box as possible. If your yard resembles a forest instead of a lawn, you may have a more difficult time attracting and keeping Bluebirds. If your yard contains too many trees and/or brushy areas, consider placing a box in a neighbors’ yard, a golf course, a cemetery, or simply place it along an open road, etc. Of course you will want to first obtain permission from your town (for municipally owned road-side nest box sites) or from property owners first. B) There are so very many predators that can injure or kill your Bluebirds. The most common ones are: cats, House Sparrows, snakes and racoons. Unfortunately many well-intentioned people place boxes on wooden two-by-fours or on fence posts and have learned the hard way that a wood mounting post becomes a welcome mat of sorts for many predators. NABS therefore recommends mounting boxes on metal poles since smooth, metallic surfaces pose a much greater challenge for many predators and result in a removal of the predator welcome mat. Metal poles communicate to predators in effect, “the welcome mat is gone­you’re going to have to overcome many obstacles to enjoy this meal.” C) Box construction is quite important for protecting your Bluebirds from predators and extreme temperatures. NABS-approved nest boxes are best because they are specifically designed to discourage predators and maintain comfortable nest box temperatures, thereby increasing the likelihood of Bluebirds survival. For more information on getting started, check out the following information on the NABS Website:

Q2: OK, I have my nestbox mounted. Is there anything else that needs to be done?
Many new Bluebird fans assume that once a box is mounted, their work is complete. However, data collected by NABS has proved that more baby Bluebirds successfully leave the nest (or fledge) if the nest box owner is pro-actively involved in the nesting process. This is commonly known as “monitoring” nest boxes. It is defined as looking in the nest box one to four times a week in order to ensure that the nest box remains an ideal environment for Bluebirds (or other protected cavity-dwelling bird species nesting in your box) to nest in, as well as to ensure that your Bluebird babies are well protected once the nest box is inhabited. Contrary to popular belief, Bluebird parents will not abandon a nest as a result of box monitoring. To learn more about monitoring, go to:

Q3: How do I know if I have the right kind of nest box for my Bluebirds?

Not every nest box is designed for the special needs of Bluebirds, even though the box is advertised for Bluebirds. First, the entrance hole must either be one and one-half inches for Eastern or Western Bluebirds, and one and nine-sixteenth inches for Mountain Bluebirds. NABS recently recommended using a one and nine-sixteenth inch entry hole for all three Bluebird species. If the hole size is larger you risk inviting visits from larger birds (most commonly the invasive European Starling) to either use your nest box before Bluebirds move in, or to evict and kill your family of Bluebirds.

While there are several different styles of nest boxes approved by the North American Bluebird Society, it is wise to start with the basic NABS style box with the distance between the bottom of the entrance hole and the floor of the box measuring at least seven and one-half inches. This prevents larger predatory birds such as Blue Jays and Starlings from reaching in the box and harming your baby Bluebirds.

Adequate ventilation holes and a wood roof surface (no roof shingles which create too much heat inside the box) are essential. Without proper ventilation, a nest box can become an oven for the baby Bluebirds during extremely hot days. They can become dehydrated and die from lack of ventilation. Also, adequate ventilation along the box floor allow rain-generated water to drain.

To reiterate, monitoring increases the chance that Bluebird nestlings will successfully fledge. Therefore, a well-constructed nest box should be easy for you to open which results in minimal disruption for your Bluebird family. Boxes that are open-roofed are no longer recommended by NABS. These boxes allow rain to easily enter the box. Wet, damp nestlings are vulnerable to developing hypothermia­especially during chilly, damp Spring weather.

A well-constructed box is usually constructed with three-quarter (or more) inch thick wood. This thickness acts as insulation that both keeps the box warmer in the cold weather and cooler in the hot weather. To learn more about proper nest box construction, check out:

Q4: Everything seemed to be going fine with my Bluebird family, but today I’ve only seen one Bluebird parent at the box. What should I do?

Open the box and check the health of the babies. If the mother died while brooding (keeping the under seven-day old babies warm at night), the babies are at risk for death from hypothermia that results from exposure due to chilly evening temperatures. Touch the nestlings. If they are ice- cold, remove them from the box one at a time and warm them in your hands. If they come back to life, contact your local wildlife rehabilitation expert immediately! If the babies are older than seven days, they will keep themselves warm at night. Sadly, they are at risk for starvation since one parent will have a difficult time feeding all of the nestlings. This may result in the surviving parent abandoning the nest. Careful monitoring will allow you to determine if the surviving parent is hanging in there or has given up and abandoned the nest. To locate a nearby wildlife rehabilitation expert, go to: or: You might also try
contacting your area or regional NABS affiliate group:

Q5: Something isn’t right because I don’t see the parents around and the babies look hungry. What should I do?

If you observe the nestlings frantically, desperately reach up for food, they are probably starving. If they are listless, they are probably beyond starving. In either case you should contact your local wildlife rehabilitation expert ASAP. Not all of the nestlings will necessarily survive, but the sooner you get them to a licensed wildlife rehabilitation expert, the better their chances. To locate a nearby wildlife rehabilitation expert, go to:
or: You might also try
contacting your area or regional NABS affiliate group:

Q6: I checked the nest box and found broken eggs on the ground outside the box. What should I do now?

Check to see if any eggs survived the predator attack in the nest and make sure that these remaining eggs do not have any small holes. If you find other eggs containing small holes, a House Wren was probably the culprit behind this invasion. The native (and therefore federally- protected) House Wren often pokes holes in other birds’ eggs as a way of taking over the nest box. If you are relatively fortunate and lost just one or two eggs from the clutch, the parents may return to the nest. If the nest was abandoned, clean it out right away and put up another box in a more open area that’s further away from the woods and brush. Who knows, your parent birds may return and try again. A good rule of thumb is to place your boxes at least 200 feet away from trees and shrubs. House Wrens usually avoid boxes placed in open fields.

Q7: I came out to check my babies, and found several of them dead and strewn out on the ground. Others were still in the box, but looked like they had been battered on the head and eyes. HELP!

Sadly, this is usually the work of the alien invasive species, the House Sparrow. These invadors are not protected by federal law and can be controlled/managed by using several approaches. Clean out the box and mount another box nearby. Your Bluebirds may return to try again in the new box. In the meantime, study ways to prevent the House Sparrows from causing so much damage in the future. For specific hints on House Sparrow control, go to: