How Baby Birds Mature

How Do Baby Birds Grow Up?

Goose Family
Baby birds go through several stages before they will look like their adult parents. Photo © Jo Naylor/Flickr/CC by 2.0

Baby birds can be confusing with their unclear markings, incomplete growth and unusual proportions. By understanding the stages of a baby bird and how chicks mature, however, birders can better identify young birds and take steps to meet their needs in the backyard.

How Long Baby Birds Need to Mature

The time from hatching to maturity varies for different bird species. Smaller birds often mature more quickly and may go from newly-hatched chicks to fledgling juveniles venturing out on their own in a couple of weeks or less.

Raptors or larger species, however, may stay in the nest under their parents' care for several months. Sexual maturity can take even longer, with small birds ready to take their first mates in a year or two, while larger birds with longer lifespans may not be sexually mature for several years. No matter how long a young bird takes to mature, however, the basic steps in the maturation process are the same.

How Baby Birds Grow

When baby birds hatch, they may be altricial, precocial or somewhere in between.

  • Altricial: Naked or sparse feathers, eyes closed, completely dependent on parental care.
  • Precocial: Covered with fluffy down, eyes open, able to walk almost immediately.

During their first days of life, all chicks require a great deal of care from their parents, even those that can walk, run or swim just hours after hatching. Parents provide warmth for the chicks, feed them or guide them to food and protect them from predators and other hazards.

At first, chicks eat several times an hour, typically insects or other high-protein foods so they can grow properly. The very youngest altricial baby birds are clumsy and wobbly, often weak and unable to move much, though they can beg with their mouths wide open to receive food. As they gradually get stronger, it may be longer between feedings, and they may develop more down feathers.

Precocial baby birds are initially much more independent and can even walk and swim right away, but in their first days they tire easily and stay much closer to their parents.

As altricial birds grow, they develop pin feathers on their wings – shafts that will eventually fan out to full feathers. Their eyes open more widely and they get bigger, slowly strengthening and moving around more. Eventually they are more completely covered in feathers, though there may still be patches of bare skin, particularly on the head and face. Their coloration is typically dull and often spotted to serve as camouflage to protect them from predators. At the same time, precocial birds are growing larger and stronger as well as developing more mature feathers that poke through their baby down.

In just a short time, baby birds begin to perch and show soft fluffy feathers on the head and face. They continue to grow larger, and the feathers on their wings become more fully developed. Their bare skin is all covered, but the tail grows out last – it is too large to effectively grow while chicks are in the nest. At this stage, precocial birds have a good number of mature feathers, but may have a scruffy appearance until they lose the last of their down.

Baby birds are ready to leave the nest several days before they can fly effectively. At this time, they flutter and hop on the ground, strengthening their wings and legs as they continue to grow. They may stay in low shrubbery or explore a greater area. This is the time when many birders mistakenly believe young birds to be "abandoned" by their parents. In reality, however, the parent birds are well aware of their offsprings' whereabouts and continue to provide food and guidance.

Eventually, the young birds are almost fully mature and can be recognized by species, though their plumage may still contain some spotting or other camouflage markings that have not yet molted away or worn off. They are very close to their adult size, but their behavior can be unpredictable and they are unsure of their surroundings.

Each day they will gain more knowledge about safe roosting spots, appropriate foods and dangerous predators.

Once baby birds have reached adult size, the next stage of their life can vary greatly. Some species keep young birds with them until the next breeding season, when they will be driven off to find their own territories, or young birds may help their parents raise another generation of youngsters. In some cases family flocks may remain together indefinitely. Other birds abandon their young as soon as the chicks are self-sufficient, letting young birds find their own way on migration or within their home range.

Helping Baby Birds Mature

No matter what types of young birds may be visiting the neighborhood, backyard birders can do a great deal to relieve the stress of growing up.

By understanding the stages young birds go through as they grow up, backyard birders can better recognize and identify baby birds as well as provide for their unique demands to ensure they mature into strong, healthy adults.