Fledging bluebirds: A few things to know

Young bluebird leaving the nest. Photo: Eric Davis.

How long before bluebirds fledge: Age of nest departure 

According to Benedict Pinkowsky (1974c), who monitored 184 nestling eastern bluebirds in Michigan, young bluebirds fledged between days 16 and 22 after hatching. Nestling bluebirds leave the nest on average 19 days after hatching, based on all 184 nestlings in the study. 

But there is a good deal of variation.

The table below includes all 184 bluebirds included in the monitoring study and the ages at which they naturally fledged the nest. 

Number of nestlings that left the  nestAge at which a nestling left the  nest
13 (7%)16 days
10 (5%17 days
40 (22%)18 days
66 (36%)19 days
21 (11%)20 days
16 (9%)21 day
18 (10%)22 days

The table and graph indicate that:

  • 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. 

Young bluebirds typically fledge earlier in the spring than they do in the summer

Some pairs raise two broods in the northern United States and Canada; one in the spring and one in the summer. Other pairs raise only a single brood in the spring or summer and do not attempt a second nest (Peakall, 1970). 

On instances where bluebirds reared a second brood, ornithologists found that spring broods took an average of 19.39 days to fledge while summer broods took an average of 18.63 days after hatching. Thus, baby bluebirds leave the nest later in the spring and earlier in the summer.

The most likely reason for such differences in age at the moment of fledging is that food is more scarce in the cold spring of northern latitudes than in the summer. In other words, baby bluebirds take a little longer to mature in the spring and be ready for fledging.

What time of day do bluebirds fledge?

According to studies of birds nesting biology, the most critical time in a bird’s development is the transition from nestling to fledgling. Young bluebirds are most at risk of predation during this period, both as nestlings and as fledglings. Predation is most common during this period.

The risk of predation is what drives the timing of fledgling, so young bluebirds must leave the nest early enough in the day to be able to find a safe perch to hide for a few days.

Early fledging would allow them to find a place to hide, even on the ground.

As with most other studies of fledgling birds, baby bluebirds tend to leave their nest around six hours after sunrise or before noon, given that weather conditions are favorable. 

In some cases, nestlings are not strong enough to fly and fall to the ground where they are at risk of predation by wild predators, cats, and dogs. Early fledging would allow them time to find a place to hide, even on or near the ground.

How does one know when baby bluebirds are ready to fledge? 

Within 12 days of hatching, baby bluebirds are mobile inside the nest, able to preen themselves and stretch their wings. They begin to peek out of the entrance hole at the world around them when they “begin to think about leaving the nest.”

On day 16, the baby bluebirds appear to compete for a chance to peek through the entrance hole. Several heads can be seen inside the nesting box. Nestlings can begin to fledge on day  16.

Nestling bluebirds can fly for a short distance by day 14, but they never leave the nest before day 16 unless something causes them to do so.

Starting about day 15, the parents decrease food delivery rates to encourage nest departure. As a result of less feeding, the nestling loses some weight, which facilitates flight. Meanwhile, the parents call the nestlings from outside the cavity to encourage them to leave.

Young bluebird taking a peek at the outside world, indicating it will fledge soon. Photo: Hawk Center of Arkansas.

The first flight

The first flight out of the nest is awkward, on a straight line, with nonstop wingbeats. After that, a fledgling wants to reach a perch as soon as possible. Typically, the parents accompany the fledglings on their first flight and seem to remember where the fledgling landed. They will return to that spot to continue feeding each newly fledged bluebird.

During the first flight, the distance covered varies from 10 to 55 yards. Some birds do not make it very far and fall to the ground because they miss a landing perch or cannot fly long distances. 

Upon leaving the nest, fledglings give a characteristic call, which the parents also use. This call helps the parents to track down and locate the fledgling. 

This is the call that fledgling
bluebirds repeat constantly after
leaving the nest.

Premature Fledging

Premature fledging occurs when young bluebirds leave the nest too early when they are still unable to maintain sustained flight. Premature fledging can be caused by predators attacking the nestlings or by humans opening the nesting box after day 12 after hatching. 

Fledging that occurs before day 16 can be considered premature. Pinkowsky’s 1974c studies showed that none of the 184 nestlings he monitored fled before day 16 after hatching.

Human-induced premature fledging

Nestling bluebirds crouch as a defense mechanism when a nesting box is opened for regular monitoring. Nestlings typically change their defense mechanism from crouching to jumping off the nest when they become more physically coordinated by day 12. 

Nesting boxes should never be opened for any reason after day 11 or 12 after hatching to prevent accidental premature fledging. 

Fledgling on the ground due to leaving the nest prematurely. Photo: Ted Peterson

How can I help a fledgling bluebird if I find one on the ground?

Often, young bluebirds fall to the ground the first time they leave the nest. It may be because they are not strong enough for sustained flight, missed a perch on their first attempt, or were forced to fledge prematurely.

Fledglings on the ground are at high risk of being preyed upon by predators such as foxes, raccoons, cats, and dogs.

If you are going to help a fledgling bluebird on the ground:

  1. Check to see if it can fly up to a tree branch or bush on its own. If you approach the nestling on the ground, it will fly away and get higher to a branch above the ground.
  2. If the fledgling cannot take flight and falls back to the ground, try helping it to climb up a tree or bush. Catch it (see below) and toss it above a low tree or bush so that it lands on it and perches on a branch.
  3. Put it back in the nesting box or cavity where it came from. Return it to the nest after catching it. 

It is natural for the nestling to immediately get out of the box and continue running away from you.  Put the nestling inside the box and seal the entrance with a rug or a sock for five to ten minutes to give the bird time to settle down. Then remove the plug to allow the parents to continue feeding the nestling. The chick would need two or three more days in the nest to gain strength to leave the nest on its own and reach a branch above the ground on the next attempt.

How to catch a baby bluebird on the ground

Assess the situation and identify the areas where you do not want the fledgling to fly or run. For example, you may have a pond nearby, a place where cats roam freely, or an area you believe is dangerous to the fledgling if you miss catching it.

Get a towel (works best) and approach the fledgling from the direction you don’t want it to run or fly. The fledgling will likely escape from you in the opposite direction from where you are approaching it. 

When you are close enough, throw the towel on top of the bird. It will run away if you get too close; you won’t hurt it. Throw the towel quickly from a distance. 

Keep the fledgling under the towel by placing your hand over the towel. Holding the bird with one hand, grab the fledgling gently with your other hand underneath the towel.

Recently fledged young eastern bluebird sitting on its first perch. Photo: Sue Crowell.

After fledging, what do baby bluebirds do, and where do they go?

After leaving the nest, they remain in hiding for about a week. The parents continue to feed them there.

Baby bluebirds tend to get closer together as they gain strength. Siblings are often seen huddled together on a single branch. When they are close together, it is easy for the parents to feed them.  

After fledging, young bluebirds continue to grow.

Young bluebirds are not fully developed when they leave the nest. Their wings are short and rounded and still growing, the same with their short tail. When young bluebirds leave the nest, their wing and tail feathers still have unsheathed bases.

After fledging, the wing and tail feathers grow to adult size in 35 to 40 days. During this period, the juvenile ceases to be fed by the parents and becomes nutritionally independent. 

How long do bluebird fledglings stay with their parents?

After fledging, young bluebirds stay with their parents for about three weeks. A field study found that the parents stop feeding the chicks around day 40 after hatching. 

Within two weeks after leaving the nest, the fledglings begin to feed themselves alongside their parents. Following the parents, they gradually take less and less food from them as they learn to forage for themselves. 

When they become nutritionally independent, spring fledglings leave their parents’ territory. The parents become aggressive towards their fledglings, perhaps to encourage total independence and start another brood. 

The fledglings from the second (summer) brood tend to stay at their parents’ territory longer, often remaining together over the winter. 

Fledglings bluebirds join flocks of other nutritionally independent youngsters. Each flock of youngsters is different in size and moves about the landscape without being attached to one particular area.

The parents continue feeding the young bluebird anywhere they land. Photo: Sue Crowell.

Do bluebirds fledge at the same time?

When all nestlings have grown equally, they usually fledge within a few hours. Nestlings who are behind in their development take longer to leave the nest. 

Nestlings develop at different rates. Some individuals may develop up to two days ahead of their siblings despite hatching on the same day. Most nestlings have long enough wings and other measurements to fledge, but those falling behind need one or two more days to develop and be ready to fledge.

After fledging, do bluebird parents sleep with their babies?

Parents do not sleep with their fledglings. For the first few days after leaving the nest, the fledglings remain hidden in separate locations. During the day, their parents know exactly where to find them to feed them, but they retreat to roost at night in one of the several cavities they typically use on their territory. 

Adult-sized fledglings that can feed themselves join flocks composed of other youngsters. Photo: Hungry Little Birdie.

Do fledgling bluebirds return to their nests?

Fledgling bluebirds do not return to the nest after they have fledged. They are physically unable to return to the nest until they gain flight strength and maneuverability.

When nestlings leave the nest, they can only rudimentarily fly. They can only fly short distances and must land on something. Experienced parents make flying in and out of the cavity look easy, but a fledgling would have difficulty doing so.

Once they leave the nest, they perch on branches and remain living in trees until they are old enough to find cavities to roost. Some fledglings may land on top of their natal nesting box about two weeks after leaving the nest as they follow their parents.

References:

  • Martin TE . 1993. Nest predation among vegetation layers and habitat types: revising the dogmas. Am Nat. 141:897–913.
  • Pinkowski, Benedict. 1997. Breeding Adaptations in the Eastern Bluebird. C., The Condor, Vol. 79, No. 3, pp. 289-302 (14 pages) Published By: Oxford University Press.
  • Plissner, J. H. and P. A. Gowaty. 1996. Patterns of natal dispersal, turnover, and dispersal costs in eastern bluebirds. Animal Behaviour 51:1307-1322.

13 thoughts on “Fledging bluebirds: A few things to know”

  1. Hi Heidi,

    Yes, it is not common, but sometimes one or two older siblings (of the year’s first brood) help raise their younger siblings. This happens to pairs that have double broods.

    What is somewhat contradictory is that the parents that attempt a second brood often drive the first brood away from the territory when the fledglings are nutritionally independent; perhaps the parents want to focus on the next brood.

    Yet, the parents would benefit from having some help raising the second brood.

    I read that older siblings help as a practice run. They will be able to breed the next year.

    Do you have helpers at one of your nesting boxes? How many helpers?

    Thank you for visiting.

    Al

    1. My nest of bluebirds fledged this morning. The two babies spent a lot of time checking out the world from the birdhouse door during the previous four days.

      During the last few weeks, there have been at least two females feeding the brood.

      1. Hi Christine,

        Great, two more bluebirds to the world!

        Two females feeding young is unusual, but it happens. I wonder if you saw the two females feeding the young while they were still in the box, or the second female appeared only after the young fledged.

        Thanks.

        Dave

  2. Are there “safe perches” we can build near the box for protection from predators? the Mom and Dad have been really busy feeding and protecting ..at least 5 babies.

    1. Hi Joan, I am not sure perches near the nesting box are necessary. Any perch intended for your bluebirds is likely to be used by predators as well. I don’t think there is a need for any additional perch. Your bluebirds chose the nesting site based on the current conditions, and they appear to be successful with what they have.

      It is probably best not to interfere, particularly now when they are feeding the young, which is a risky period for predation. Baffles and predator deterrents on the pole that sustain the box are the best defense against predators.

      Regards,

      Al

  3. I’ve noticed other birds sitting on the fence and even on the nesting box. The babies should be fledging any day now. Will the other birds attack the babies?

    1. Hi Lisa,

      No, those birds near the nesting box are doing their own things. They are not a threat to the fledglings. Unless one of them is a hawk or other predatory birds likely to attack newly fledged baby bluebirds.

      Also, I doubt those birds are looking into taking the nesting box as it is now a bit late for any bird to start a new nest.

  4. We recently had a bluebird couple build a nest in a birdhouse that’s only about 3 ft from the ground, in our flower garden about 10 ft from out house. We watched for weeks as the couple flew in and out of the house’s hole. Eventually, we saw little heads peeking through the hole and the parents flying back and forth constantly feedin them. Always a flurry of parental activity throughout the day and early evening bring food.
    Then , one day earlier this week, there was no activity. No parents. So we assumed the nestlings had fledged. For three or four days there has been no signs of bluebirds. No activity. I had been reading that we are supposed to remove the nest and clean the birdhouse….but yesterday around 5:30 pm and again today at the same time , the parents have come back. No food in their mouths, but they each take a turn looking into the entrance hole — just their heads. And only one look each. The female perches on top of the birdhouse for a minute or two as well. Then they fly off.
    What does this parental behavior mean? Did something happen to the nestlings and they did not fledge? I haven’t wanted to get closer than 4 ft away from the birdhouse, so I can’t really see inside the house, but if they’re alive inside they aren’t getting fed.
    What should I do? What’s going on? And..when do I have to clean out the box, because it’s wooden, decorative, and there’s no way to open it to clean it.
    Thank you for your advice. I’m so worried.
    Lynn

  5. Hi Lynn,

    If the chicks were peeking out through the nesting box hole, chances are they have fledged. They likely are at separate spots, and the parents are feeding them. Right about now, since the time they apparently left the nest, they should be getting better at following the parents around rather than waiting for the parents to come to where they are to be fed. As to why the parents came back to check inside the nest, cavity-nesting birds do. After all the chicks have fledged, they still come back to see if there are any left in the cavity. Although you saw adult birds nearly a week after the chicks apparently fledged…this is a little different. Could they be a different pair of adults just checking the nesting box, maybe? Or just the parents checking the box for some reason.

    Question: Right after the activity stopped, did you see the parents persistently coming to the nesting box with food? If this was the case, the parents were trying to feed the young in the nest because there aren’t any other fledglings to feed elsewhere. This could indicate that predators took the chicks. But if they disappeared altogether, it is more likely that they fledged.

    Regarding approaching the box to see what is in there and cleaning it up, go ahead and do it. At this point, it is most likely that there is nothing in the box. You can use a small mirror and look inside before proceeding.

    Do not worry about disturbing the parents. Bluebirds are quite tolerant, and they are not likely to start another nesting attempt at this point in time. It is too late.
    I hope this helps.

    Regards,

    Al

    1. Hi Al,
      Thank you so much. This info helped tremendously. No, we didn’t see parents with food after the activity stopped, so we believe they all fledged successfully. Today, we opened the birdhouse and a very neat, square pine needle nest was inside. I removed it carefully, intact.
      I’m cleaning the inside with a week solution of distilled white vinegar and water, instead of bleach. I hope that’s okay. After letting the interior dry, and screwing back the bottom, should I put the nest back in? Or Is there a proper way to dispose of it?
      We were so lucky to have a pair nesting this year. We have bluebirds here in NH year round, and at our feeders ( we take the feeders down June – Sept). It’s amazing they nested in this silly little kitschy decorative old birdhouse only 3 or 4 ft from the ground inside our wildflower garden near some 6’ tall miscanthus grasses.
      Thanks again.
      Lynn

  6. The nestbox chosen this year is just above a 10′ area that gets extremely wet in this monsoonish rain/thunderstorms we’re having in the NE. The chicks are about 10 days old now I think…so I’ll stop monitoring. But what about the storm puddle? If it’s wet on any day after day 16 do you think I should put a tarp down or something in case they fall to the ground?

    1. Hi Thalia,

      While the puddle formation is something unusual, I don’t believe you should be overly concerned about it. First of all, I imagine that there are puddles everywhere. It would be impossible to predict where fledglings are going to land when they leave the nest. Perhaps more important is the fact that only a small percentage of young bluebirds fledge prematurely and fall to the ground, unless they are forced to do so.

      It is a good Idea that you are stopping monitoring the nest. This will help young bluebirds take their time and leave the nest when they are ready to do so, which means they are unlikely to fall to the ground. They will do just fine.

      Regards,

      Al

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