Birds staying in the nest beyond the typical timeframe is a phenomenon seen in some species. There are several reasons why certain baby birds do not leave the nest at the expected age.
Do All Baby Birds Leave the Nest at the Same Age?
No, there is variation in the age at which different species fledge, or leave the nest. The fledging period is the length of time from hatching to leaving the nest. This period ranges from 11-70 days across different bird species.
For example, grebes and rails fledge in just 11-12 days. On the other hand, large birds of prey like eagles, ospreys, and vultures have fledging periods of 8-14 weeks. Albatrosses take even longer, around 22 weeks to fledge.
So it is normal for different birds to leave the nest at very different ages. The long fledging times of large birds allow the nestlings time to grow their flight feathers and build up wing muscles needed for flying.
Why Might Birds Stay Past Their Normal Fledging Period?
While there is natural variation across species, sometimes individual nestlings remain in the nest longer than what is typical for their species. Here are some potential reasons for delayed fledging:
Injury/Disability
Nestlings that are injured or disabled in some way may be unable to leave the nest at the normal fledging age. For example, an injury to a wing or leg can prevent mobility or flight. Unhealthy or undernourished babies may also be weaker and slower to develop flight ability.
Predation Threat
High risk of predation prior to fledging may lead parent birds to make the decision to keep babies in the nest longer. Birds such as wrens and finches often delay fledging by several days if there is perceived danger from predators around the nest site.
Poor Weather
Fledging typically occurs in ideal dry weather with low wind, as this gives young birds the best chance for a successful first flight. Some parent birds may choose to wait out a period of storms, cold temperatures, or other inclement weather before encouraging nest exit.
Insufficient Parental Care
Babies require adequate feeding and parental care in the nest. If parents do not provide enough resources, the young may develop and grow more slowly. Lack of food and feeding can delay feather growth and fitness. Nestlings may stay past normal fledging time if parents are diseased, struggling to find food, or if one parent dies.
Nest Competition
Bird parents often encourage the oldest, most fit babies to fledge first. Weaker chicks continue occupying the nest while the strongest babies leave earliest. This reduces competition for food and parental care. Slower-developing chicks may remain weeks behind their older siblings.
Fear/Uncertainty
Some nestlings seem reluctant to take their first flight and leave the safety of the nest. Unfledged birds may require coaxing or encouragement from the parents when they seem hesitant or fearful to fledge.
How Long Can Baby Birds Stay in the Nest?
There is no set limit on how long is okay for baby birds to remain past fledging age. Parents play a key role in motivating young birds to finally take flight. Here are some general timeframes:
- Songbirds: Normal period is 2-3 weeks. May stay up to 2 extra weeks if injured, ill, or weather is poor.
- Seabirds: Normal 6-10 weeks. May stay up to 3-4 extra weeks if not developing well.
- Birds of prey: Normal 8-14 weeks. May remain up to 6 extra weeks if injured or ill.
However, there comes a point at which a baby bird staying in the nest becomes a serious concern. See the warning signs section below.
Warning Signs a Baby Bird Needs Help
While an extra couple of days in the nest may be normal, at a certain point a baby refusing to fledge becomes problematic. Here are some warning signs that a nestling staying in the nest needs intervention or help:
- Nestling is approaching twice the normal fledging period for the species
- Weight loss or emaciation
- Labored breathing, drooping wings/head
- Injury preventing mobility
- No parents visits after several hours
- Dead parents or deserted nest
- No improvement after 2-3 extra weeks in nest
- Attack or ejection by parents or siblings
At this stage, the baby is either unable or unwilling to fledge. Leaving the chick in the nest would likely result in starvation, predation, or death. Human intervention is often required.
What to Do With a Late Nestling?
An unfledged baby alone in the nest or reluctant to fledge will need help. Here are some recommendations if you notice this situation:
Contact a Wildlife Rehabilitator
The best action is to contact a local wildlife rehab expert right away. Licensed rehabilitators have the training and resources to properly assess, care for, and treat unwell nestlings. They will reintroduce the bird to the wild once it is healthy and developed.
Leave the Bird Alone
If the nestling appears healthy and parents are still caring for it, monitor the situation but leave the bird alone. The parents may be waiting for ideal conditions or for their offspring to gain strength. Allow extra time before intervening.
Assist the Bird
As a last resort, you can attempt to help an unfledged baby leave the nest if its situation is dire. Use thick gloves to place the bird on a nearby branch. Monitor to ensure parents resume care. Be prepared to call a wildlife rehabilitator if parents do not return to feed the fledgling within a few hours.
Can a Bird Fledge Successfully if Delayed?
Yes, late fledging can still result in healthy birds joining the wild population. With proper rehabilitative care and treatment, fledglings initially unable to leave the nest due to injury, illness, or poor development can make a full recovery.
Even birds that fledge days or weeks behind schedule can prosper. As long as the juvenile bird is able to master flight and feed itself after leaving the nest, an extended nestling phase does not prevent ultimate independence. Survival rates may be slightly reduced compared to birds that fledge normally, but late fledgers can still thrive.
Preventing Late Fledging Problems
Here are some tips for supporting baby birds so they are ready to fledge in a timely manner:
- Do not disturb or tamper with active nests, as this can stress parents and delay feeding
- Keep cats indoors so they do not injure nestlings and frighten parents
- Install nest boxes to provide safe breeding sites away from predators
- Plant native vegetation that produces berries and seeds to help parents feed their young
- Avoid pruning trees and shrubs during peak breeding season
- Keep windows screened or break up reflections that can confuse fledglings
Supporting breeding birds allows them to successfully raise healthy, fit young prepared to leave the nest on time. Only a small percentage of nestlings should need help fledging.
Conclusion
Most baby birds fledge from their nest within a fairly predictable timeframe for their species. Normal development issues, weather factors, injuries, disabilities, lack of care, and nest competition can all contribute to some individuals staying in the nest longer than expected. While a few extra days may be acceptable, extremely late fledging or a chick unable to leave the nest at all requires rehabilitation or intervention. With appropriate help, late fledgers can still grow into independent juvenile and adult birds.
