Jacqueline McFarland, age 11, of Society Hill, South Carolina, for her question:

Which bird lays the biggest egg?

One would expect the biggest bird to lay the biggest egg. And this is so. It also is true that the smallest bird lays the smallest egg. But this rule does not hold true throughout the bird world. In New Zealand lives a rather shy chicken sized bird weighing four pounds. And of all things, this little mother lays an egg that weighs one whole pound    which is a quarter of her total weight. Wow!

The largest living member of the bird world is the stately ostrich of the African plains. He stands seven feet tall and tips the scales at around 300 pounds. The egg of the female ostrich measures five and a half by seven inches and weighs three pounds. Without a doubt, it is the largest of all bird eggs    and she may lay a dozen of these whopping eggs for one nesting.

Since ostriches live in lion country where life is quite hectic, special precautions must be taken to make sure that the eggs have a chance to mature. During the dry season, the ostriches roam in large herds searching for anything eatable. As the rainy season approaches, they separate for the mating season which opens with dances and courting rituals.

Sometimes a male and female pair off to raise a family. More often a male gathers two or three females. In any case, he scoops a hollow nest on the ground about three yards wide. This is shared by all the females and three dozen huge white eggs may be placed in the huge nest. Then either the male or the strongest female drives the other mothers away. The two remaining parents tend and protect the eggs for six weeks.

Often the boss male bird tends the nest at night. The boss lady bird takes the day shift when the problem is to protect the eggs from the sizzling sun. This she does by spreading her large wings like sunshades over the nest.

Somehow the big birds know how the eggs are progressing. For as hatching time draws near, the more advanced eggs are pushed to the edge of the nest. This delays progress so that all the eggs hatch at about the same time. The perky chicks are ready to go almost at once and in a month they can race along at 35 miles per hour.

The female ostrich weighs almost 100 times more than one of her huge eggs. But compared with the shaggy little kiwi, this is nothing to brag about. This shy little four pound bird of New Zealand lays a greenish black egg that weighs one pound. If the ostrich could complete with this record, her egg would weigh about 70 pounds.

The egg of the bee hummingbird measures about a quarter of an inch and it takes about 200 of them to weigh an ounce. She is the world's smallest bird. The egg of our great bald eagle is three and a half inches wide and almost three inches long. Wild goose eggs are longer than three inches and the eggs of the smaller wild ducks are less than three inches. The eggs of our small songbirds measure less than an inch    all of which seems logical.