Saturday, April 19, 2008

Birds Known By Their Eggs

This spring, think eggs!

Nesting time has rolled around again. Not only will the shape, size, material used and in what situation the nest is placed (a thorny vine, low shrub, in a hedge, in a tall tree, or on a shelf) tell you who the owner is, but the eggs will sometimes clinch the identification.

A bird's egg is one of nature's masterpieces. From the tiny eggs of the hummingbird to the large eggs of the Canada goose, there are remarkable differences.

The range of colors, shapes and markings on bird's eggs are incredible. Many blend perfectly with their surroundings.

For instance, the killdeer's light buff with bold blackish-brown or black blotched eggs blend so well with the surroundings that it takes a sharp-eyed person to find them. This bird builds no nest but deposits the eggs in a slight depression of debris or pebbles. Around a home, a good chance to hide the treasure is a gravelly driveway.

Many of us have cardinals nesting in our yards. If you are not sure the nest you have found is that of a cardinal, being able to identify the eggs will help in its identification. The ground color of the greenish-white, heavily speckled and spotted with different shades of brown will tell you the nest is that of a cardinal. The clutch is usually four eggs.

The mockingbird is another common yard bird. Although material used in its nest is decidedly different than the cardinal's, the eggs are much alike in color and size, and might be hard for one to determine the owner. The bluish or greenish ground color is heavily marked with various shades of brown. To be sure which eggs you are seeing, the difference in the nests would be your best clue. Seeing the owner at home would be indisputable.

There's a great variety in bird's eggs . . . in number, size and color. Yard birds such as robins, cardinals, towhees and brown thrashers produce a clutch of four eggs usually, but sometimes there might be a large set of five or six. The Carolina wren's usual clutch is six slightly buffy colored, reddish-brown spotted eggs in a dome-shaped nest.

Brown thrashers nest at least twice in a season, with robins, cardinals and towhees nesting commonly three times. In the South, the nesting season is longer than in northern states. We had a towhee in our yard once whose young fledged in mid-September.

Cavity nesting birds usually lay pure white eggs. Owls, some hole-nesting, others in open nests, lay pure white round eggs. All woodpecker's eggs are white.

A flicker's nest was found in a felled tree and I examined the eggs. Although the shell was white, the eggs had a pink glow. The shell was translucent and the yolk showing through it caused a lovely pinkish blush.

The eggshell of most song birds is spotted with shades of light to dark brown. Many species of birds have eggs spotted with purple and lilac along with brown and black. Eggshells vary from white, glossy white, buff, to different shades of light blue to blue greens and various shades of green.

No one clue may be enough to ensure accurate identification. It is by the combination of several pieces of evidence that you will succeed in your search to "know your eggs".