Guest Author - Kimberly Weiss
I was watching the Easter special of the incredible Martha Stewart yesterday, and what impressed me the most—well, besides the fact that she apparently had a huge party for several dozen strange children, with a guest appearance by the “real” bunny—was the different eggs she dyed.
Most of us who celebrate Easter, like myself, go to the store, by a dozen or two white chicken eggs and proceed from there.
Not Martha. Not only does she have chickens that lay eggs of different colors, but she also dyes eggs from different birds. She and her nieces dyed or made crafts from an ostrich egg, a rhea egg, and a blue duck egg. The differences in size and shell color vary greatly from bird to bird.
So, just in time for Easter, here are some egg-cellent egg facts.
The egg is a reproductive cell. Eggs have only one set of chromosomes. They must be fertilized with sperm to make a baby. Sperm also has only one set of chromosomes.
The female of every species in the animal kingdom produces eggs. The eggs of most mammals, including those of humans, are really only seen by scientists or doctors doing fertility treatments. They never need to leave the body, because mammals make babies through internal fertilization. If you don’t know what that entails—well, I won’t describe it here, as this is a family column. Ask your parents!
Birds, fish, amphibians and reptiles make their babies through external fertilization. This means that the female has to lay the eggs—they must leave her body. Fish and amphibians lay thousands of tiny, soft eggs. If you’ve ever eaten caviar, you’ve eaten a fish egg.
The eggs of reptiles and birds are actually pretty similar, which is why most evolutionary biologists think that birds evolved from reptiles. The eggs of both animals are hard-shelled and fairly large.
The smallest eggs are laid by the vervain hummingbird, a native of the Jamaica and the Dominican Republic. Their eggs are less than a half inch long. The vervain hummingbird is the second smallest bird in the world. The smallest bird is the bee hummingbird, from Cuba. The eggs of that species are described as being the size of peas—tiny, but still slightly larger than that of its cousins across the Caribbean.
The ostrich lays the largest egg of all the birds living today. An ostrich egg is about 6-8 inches long. The largest bird egg ever recorded—and in fact, the largest egg of any species known to science—was laid by the extinct elephant bird.
Unlike most gigantic species (dinosaurs, sabre-tooth tigers, mammoths) that have been gone since prehistoric times, the elephant bird went extinct around 400 years ago, a victim of hunting and settlement in its native Madagascar. Like most giant birds, the elephant bird was flightless.
Glands in the uterus of a female bird secrete different pigments. These pigments are responsible for the color of the eggs. The colors and designs on an egg are determined by the speed the egg was traveling down the uterus when the pigments were released.
White is the most common egg color; blue eggs are also common. Robins, starlings, bluebirds and red-winged blackbirds all lay blue eggs.
In general, the deeper the nest or cavity that the eggs are laid in, the lighter the eggs are. Birds that nest in cavities (owls) or nest boxes (wood ducks) usually lay white eggs.
Birds that lay blue eggs usually nest in a more shallow nest.
Birds that lay eggs on the ground often lay earth-toned eggs. Killdeer and towhees are examples.
Birds that nest in branches have blotchy eggs. Orioles and cardinals are examples of this phenomenon.
Happy Easter and Passover.