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Eggs

Four Piping Plover eggs (Courtesy NEBRASKAland Magazine/NGPC)

All birds lay eggs. Bird eggs have a hard outer shell that protects the baby bird while it's developing inside.

Egg shells have various colors and patterns depending on the type of bird that laid them. Robin eggs are blue. A Least Tern has tan eggs covered with darker splotches. A Least Tern's eggs might be less colorful than a Robin's egg, but that's just as well – the splotchy tan blends in with the surrounding sand, giving the egg natural camouflage.

The eggs in a nest are referred to as a clutch. The number of eggs in a clutch varies. A Wild Turkey nest can have fifteen or more eggs in a clutch; a hummingbird will lay just two eggs.

The period when the parent is taking care of the egg in the nest and the bird is developing inside the egg shell is called the incubation period.

During incubation, the parents keep each egg warm and do their best to guard it from predators. The incubation period is different for different birds. For example, for small birds it's ten to twelve days.

When the baby bird inside is ready, it hatches out of the egg. The shell that was strong enough to protect the baby bird throughout its incubation is broken to pieces by its former occupant, who is now a nestling.