The Life-Cycle Of A Bird: From Egg To Hatchling To Adulthood

Most baby birds are not born ready to fly off into the sunset. Just like humans, they go through stages of development before they are considered to be adults. Unlike humans, various species of birds go through this aging process in different ways. This process is designed to get birds ready to leave their nest. They aren’t born ready to fly and must take time post-hatching to prepare for flight. 

We are going to take a look at telling how old songbirds are, as birds like owls and ducks skip various stages. Read on to find out how to tell how old baby birds are.

Life cycle of a bird

Still In The Egg

Baby birds have various incubation times, but small songbirds can take anywhere from 10 days to 2 weeks to hatch. While in the egg, the bird transforms from a tiny embryo into a chick ready to shatter the egg ceiling. The number of eggs per nest varies with each species. Condors will produce one egg at a time, and gray partridges can produce up to 17. 

When the babies are ready to hatch they will use their egg tooth, a small bump on their beak there specifically for this purpose, to crack through the shell. It can take anywhere from mere hours to a few days to break through the shell.

If you see an egg laying on the ground and are unsure if it is still alive, check to see if it is still warm and unbroken. You can also place it under a bright light – if there are visible veins, it is still alive. If you’re incubating an egg, watch for signs of movement. If you’re wondering if an egg inside a nest is still alive, watch to see if the parents return to it. If they return, the egg is still alive.

Hatchling: 0-3 days old

After the baby bird cracks its way through the shell, it becomes a hatchling. The hatchling period usually lasts between 0 and 3 days. The baby is now strong enough to last outside of its shell, but it is still not able to function as an adult. 

A hatchling will not have yet opened its eyes, and they don’t have much muscle strength and therefore can’t move much. Due to their weakness, hatchlings can’t survive without their parents. This makes hatchlings incredibly vulnerable. 

Nestling: 3-13 days old

A hatchling becomes a nestling on day 3. By this point her eyes have opened. This stage is important for wing growth. A nestling baby bird will have stringy tubes where her wings will go. The wings haven’t yet broken through this protective sheath, so the baby is still bound to the nest and reliant on its parents for survival. 

The nestling age is not as important as the milestones the baby has hit. The stage of development is more telling than the number of days old the baby is. If you see a baby bird with open eyes and small tubes, know that it is a nestling baby until it is ready to leave the nest. 

Fledgling: 13 days or older

Once the bird has developed its wings, it is now a fledgling. Fledgling birds are still small but fully feathered. Its wings and tail will be shorter than that of its parents. While not yet able to fully fly, these little fledglings can hop, flutter, and walk around on their own. They will have left the nest by this point. 

It may seem like there is a problem with the fledgling as their jerky movements can make a concerned bird watcher think it’s injured. But fear not, these babies are still just learning how to move themselves around outside of the nest. It is best to leave them alone to figure out what to do for themselves. This is a very important developmental stage for the babies as they are learning important lessons when it comes to movement. 

Juvenile birds

As mentioned before, the exact age of a bird is less important than the developmental milestones it has hit. Juvenile birds are in the middle ground between childhood and adulthood. Birds can go through a juvenile stage – it has mastered skills needed to survive on its own, like flying and finding food, but it still isn’t considered an adult. 

Some birds might still look small and unproportional, or maybe its markings aren’t yet what an adult’s are. Not all bird species experience this. A common example of a juvenile bird is the bald eagle. Born with brown heads, bald eagles aren’t considered to be fully adult birds until their crown turns white. Bald eagles with brown heads are capable birds, but they are not yet fully mature until their markings are in line with other adults. Bald eagles can be in the juvenile stage for multiple years. 


An adult bird will be fully developed and able to fly, catch food, have all its adult markings, and can reproduce.

Birds that Skip Developmental Stages

It can be harder to determine the age of some species of baby birds due to their unique staging. Owls and ducks break free from their shells ready to fly, bypassing the hatchling and nestling stages altogether. Other birds could take longer than two weeks to develop. 

As always, look for developmental stages. If a bird cannot yet fend for itself on its own and doesn’t yet look like that species’ adults, then it is not yet an adult. 

A baby bird’s transition into adulthood is a beautiful transformation. From a defenceless hatchling to a stringy nestling to a hopping fledgling, these birds go through distinct stages that let bird watchers know just how old they are. Baby birds are a delight to watch. Grab your binoculars and start watching these birds make the transition from egg to adulthood.