Wild Georgia: From egg to fledgling, baby bird’s growth is natural wonder

A juvenile bluebird visits a birdbath in Decatur. Juvenile is one of several development stages that baby songbirds go through to reach sexual maturity as adults. (Charles Seabrook for The Atlanta Journal-Constitution)

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A juvenile bluebird visits a birdbath in Decatur. Juvenile is one of several development stages that baby songbirds go through to reach sexual maturity as adults. (Charles Seabrook for The Atlanta Journal-Constitution)

Spring migration is over. It’s now prime nesting time for Georgia’s songbirds, most of which are incubating eggs or tending babies. Several year-round birds — bluebirds, cardinals, Carolina chickadees and others — are raising their second brood of the year.

Rearing a clutch of babies is an arduous task for songbird parents, but, in my mind, the growth and development of baby birds is one of spring’s greatest natural wonders. From hatching to learning to fly, several different development stages are crucial for baby birds to become successful adults.

In general, ornithologists describe five to seven stages that a baby bird goes through during development. Here’s a look at the stages for one of Georgia’s most common songbirds, the Eastern bluebird:

• Egg. A female bluebird lays four to five light blue eggs and incubates them for about 14 days. Inside the egg, an embryo miraculously transforms into a chick, which has a temporary “egg tooth” to crack open the shell and enter the world.

• Hatchling. Newly hatched bluebirds are altricial, born featherless and with eyes closed. They’re totally dependent on their parents for food and warmth and can’t move around much because of weak muscles.

• Nestling. About three days after hatching, the baby birds can open their eyes. Now they’re nestlings. Downy fluff emerges to cover their bare skin. Their feathers begin to appear, and they generate their own body heat. They still rely on parents for survival, but after about 14 days, they have become fully feathered and mobile enough to fledge the nest.

• Fledgling. The fledglings can leave the nest and hop, flutter and walk about on their own. They rapidly acquire a set of flight feathers and start taking short flights. They will, however, continue to associate with parents for up to three weeks until striking out on their own as juveniles.

• Juvenile. It takes about nine months for juvenile birds to acquire full adult plumage and become capable of breeding, but they’re essentially on their own.

• Adulthood. The birds are sexually mature, capable of having their own babies.

IN THE SKY: From David Dundee, Tellus Science Museum astronomer: The moon will be new on Monday. Venus, Mars, Jupiter and Saturn (rises just after midnight) are low in the east a few hours before sunrise. Mars and Jupiter appear close together in Sunday’s pre-dawn sky.

Charles Seabrook can be reached at charles.seabrook@yahoo.com.