Daily News-Record, April 5, 2023
A fun activity during Easter season is to dye the white eggs of domesticated chickens, but some wild birds produce eggs that are already beautifully colored when they are laid. The South American Tinamou — a somewhat fowl-like bird in its habits — lays eggs that are variously colored in brown, yellow, blue, green and purple. If we could get our chickens to do that, we would not have to dye their eggs for the Easter holiday!
Scientists believe the first birds to evolve laid white eggs just as their reptilian “cousins” still lay today. But apparently, pigmentation that occurred by chance through the ages must have helped eggs to survive and therefore became standard coloration for some species of birds.
Most eggs are marked in such a way as to help them blend into their surroundings. An egg may be splotched with brown or reddish-brown spots at one end or colored all over in the hues of the dried twigs and leaves that make up the nest in which it is found. Eggs that are laid in burrows (such as those of kingfishers) or cavities (such as those of woodpeckers) tend to be white because they are not out in the open where a predator could easily spot them.
Some birds, however, lay beautifully-colored eggs that don’t seem to be well camouflaged. For example, robins and other thrushes lay gorgeous blue or greenish-blue eggs.
One of my first memories is of a blue robin’s egg that had somehow fallen — unbroken — into our tiny fenced-in yard when I was probably no more than three or four years old. The little egg fascinated me with its beauty and I felt it was a tiny treasure, the likes of which I had never seen before. I wanted to keep it, being too young to realize that federal law prohibits possession of bird eggs without a permit, but my older brothers insisted upon placing the egg upon the fence. They thought the parent bird might be able to retrieve it. I was heartbroken when I later found the precious blue egg lying broken on the ground where it had again fallen, this time into numerous pieces with its insides spilling out.
Although an eggshell seems to us to break very easily, it’s a prison to the bird enclosed within. The young avian creature needs to have a sharp “instrument” to escape, and that instrument is an egg tooth, a rough hard projection at the tip of the upper mandible of the bird’s beak. The chick’s movements within the shell cause the egg tooth to scratch the inside surface of the shell, weakening it. After the bird breaks out of its “prison,” the egg tooth disappears.
What I’d really love to see is the egg that’s laid by a warbler in Japan; it’s red, my absolute favorite color. A cuckoo that lays its eggs in the nest of this warbler also lays red eggs, matching the host bird’s eggs.
Happy Easter and Happy Spring!
Marlene A. Condon is the author/photographer of The Nature-friendly Garden: Creating a Backyard Haven for Plants, Wildlife, and People (Stackpole Books; information at www.marlenecondon.com). You can read her blog at https://InDefenseofNature.blogspot.com