FAQ's on Bluebird Nesting Habits

When do Bluebirds start nesting? As early as February – April for the first nesting. Sometimes later if first-time nesters or multiple nesters.

What do they use for a nest, and what does a Bluebird nest look like? Bluebirds typically use woven grass, pine needles, straw, hair and sometimes feathers. Typically there will be no seed heads, cigarette butts, strings, sticks, or other junk in a Bluebird nest. See FAQ's on Competing Species if you suspect the nest in your Bluebird nestbox is that of another species.

How many broods do they have? Usually Bluebirds will have two nestings, or in favorable conditions three.

How many eggs per nest, and what do they look like? The eggs are laid one each day until the entire clutch is complete, usually 4-6 powder blue or, occasionally, white eggs.

          
How long till they hatch? Incubation lasts approximately 12-14 days for Eastern, 13-14 days for Mountain and 13-14 days or Western Bluebirds. Incubation usually begins right after the last egg was laid, but sometimes the female will wait a day or two.

I saw one of the adult birds carrying something white out of the nestbox. What was it? The parents are very meticulous about cleaning up the nestbox. When the eggs hatch, the female usually eats the eggshells to help with her egg production or disposes of them far away from the nestbox. While the babies are growing, the parents will carry away the waste products from the nestlings. The waste is in the form of neat little bundles called "fecal sacs".
 

Picture of fecal sac stuck to nestbox wall.
It will be gone in just a few minutes!

How long till they leave the nest? After hatching the chicks will remain in the nest for 16-22 days for Eastern, 17-22 for Mountain and 19-22 days for Western Bluebirds. You SHOULD NOT open the box for monitoring after the 13th day after hatching or the chicks might fly from the box prematurely. The fledglings look surprisingly unlike the adult birds. They are speckled with touches of blue on the wings.
 

If I touch the eggs or babies, will the adults abandon the nest? No. Bluebirds are quite tolerant of human monitoring of their nests. Sometimes the eggs or babies must be touched in order to resolve a dangerous problem from a predator or pest. Of course, unnecessary handling of the nest, eggs and babies should be avoided. See the FAQ on Predators and Pests for further information.

Who feeds the babies? Both parents feed the babies. Often fleglings from a previous nest also help with the feeding. It’s a family affair!

Should I clean out the nest after fledging? Yes, take nest out and if no parasites, save it in a plastic bag for emergency nest changes. Microwaving the nest briefly – (no more than one minute or it will stink!) - can kill any undesirable bacteria or hidden bugs. Wash inside of nestbox with a mild solution of bleach and water. Some sources say 1 part bleach to 10 parts water, other sources suggest a 1:32 ratio. In either case, flush with plain water after disinfecting. Leave door open until it dries. Females have been known to start a second nest within a day of fledge day and occasionally will start a second nest in another box even before fledging occurs in the current nest.   For this reason, the box should be cleaned the day after the last baby fledges or sometimes, that very day. The old nest should always be removed and disposed of far away from the nestbox.   An old nest, thrown away near the nestbox can draw predators.   Place the old nest in a plastic bag and put it in the trash.

The babies fledged, and now they have disappeared! What happened? It is not unusual for the adult birds to take the new fledglings somewhere away from the nesting site for a period of time. If you have been feeding mealworms to the adults, then it is likely that they will continue to come for them after the babies fledge. You may get an idea of where they have taken the babies if you watch where they go when they fly away with mealworms in their beaks. Don't worry -- the babies will probably return with the adults after a couple of weeks to teach them where they can find the mealworms for themselves. It is also quite common for the adult birds to chase away the fledglings from previous nestings once the next clutch is ready to fledge.

How long will the Bluebirds stay? This depends to a great extent on where you are located, and food sources. Bluebirds do not necessarily migrate if there are plenty of native berry bushes that they can feed on during the winter months. They may seem to disappear for a few weeks in late August-early September only to return a few weeks later. If you had been feeding mealworms during the summer, and wish to continue doing so for the winter, you might possibly have a group of Bluebirds stay with you for the winter. During nesting season, the birds are very territorial, but when nesting season is over, they tend to live in loose flocks comprised of the parents and young birds from all the nestings from the season.

More FAQ's:
Bluebird Housing
Feeding
Competitors
Predators, Pests, Parasites and Other Problems
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