Posted on Tuesday, May 17, 2011 by eNature
Ever wonder why birds lay eggs of different colors and shapes?
There’s a good reason for just about everything we encounter in nature and, as you’d expect, eggs are no exception.
While we tend to not talk much about bird nests at eNature.com because we just don’t want to encourage folks to disturb nesting birds, bird nests and the eggs in them are full of interesting stories.
Why aren’t all bird eggs white? Birds’ eggs are colored for protective reasons. The parent birds that incubate them are not always on the nest covering them, and at those times, the eggs are exposed to predators. The color, speckles or spots on them are camouflage. That explains why birds that nest in cavities often lay all white eggs. They can’t be seen even when the parent birds are not sitting on them.
Why are birds eggs shaped differently? Again, to protect them. Birds that nest on cliffs, such as many seabirds, tend to have eggs that are smaller at one end than at the other. This is to make them roll in a circle and less likely to fall off the cliff. Birds with round eggs, usually build deep nests that keep them from rolling out.
How do baby birds hatch? They have a so-called “egg tooth” on the top of their upper mandible, which cuts through the egg shell when it is time for them to come out. The egg tooth falls off soon after hatching.
Why do the eggs in a nest often all hatch at about the same time? Because most birds lay an egg a day, but do not begin incubating them until the last egg is laid. One notable exception is the barn owl, which begins incubation with the laying of the first egg. That’s why the youngsters in a brood range in size and age from the oldest to the youngest.
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