- How long before bluebirds fledge: Age of nest departure
- What time of day do bluebirds fledge?
- How does one know when baby bluebirds are ready to fledge?
- Premature Fledging
- Human-induced premature fledging
- How can I help a fledgling bluebird if I find one on the ground?
- How to catch a baby bluebird on the ground
- After fledging, what do baby bluebirds do, and where do they go?
- How long do bluebird fledglings stay with their parents?
- Do bluebirds fledge at the same time?
- After fledging, do bluebird parents sleep with their babies?
- Do fledgling bluebirds return to their nests?
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 nest||Age 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.
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 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.
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:
- 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.
- 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.
- 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.
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.
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.
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.
- 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.