It's baby bird season! You'll often hear such words as chick, juvenile, fledgling, and nestling used to refer to young birds, but they don't all refer to the same stage within a bird's life cycle. It can be confusing to try to figure out which term refers to which stage, and even a few historical ornithological documents have gotten it wrong. However, we've rounded up the correct terms used within traditional ornithology to describe the baby birds you might see this spring.

Hatchling

Purple martins typically lay four to five pure white eggs in a nest of leaves, twigs, debris, and mud. —Cyndie H., Cortland, OH

A hatchling is, essentially, a bird that's just hatched from its egg. It will continue being a hatchling until it stops relying on its yolk supply for nutrition, or when it becomes capable of regulating its body temperature on its own.

Nestling

These familiar backyard thrushes nest in a wide variety of places, including trees, shrubs, gutters, light fixtures, and porches. —Linda J., Blanchard, ND

Once a hatchling begins to rely on its parents for nutrition and can self-regulate its temperature, a bird becomes a nestling. Nestlings are unable to fly and spend their days living solely within the nest.

Chick

These eight young wood ducks are sticking close to Mom (and to each other!). —Kim G., Galloway, OH

When a young bird leaves the nest and can walk in a family group (as you might see among waterfowl and galliformes), it is considered to be a chick. Note that young birds still cannot fly at this stage.

Fledgling

The fledgling stage begins when a young bird can finally fly. However, it is still not completely independent, and continues to rely on its parents for care and nourishment.

Juvenile

The juvenile stage in a bird's life is marked by its first plumage without downy feathers. The feathers at this stage are soft, wear away quickly, and will not last into adulthood. At this time, the bird is still sexually immature and unable to breed.

Immature

Once a bird is capable of breeding, and after it has molted its soft feathers and replaced it with hard ones, it is considered immature. The new plumage at this stage is markedly different in color or pattern from that of adults. Note that not every species of bird goes through the immature (also known as “subadult”) stage. Many birds proceed directly from the juvenile stage to adulthood.

Adult

If a bird is capable of breeding and maintains a plumage that does not change with successive molts, or it follows a distinct breeding/nonbreeding plumage pattern across seasons, then it can be considered an adult.