It turns out that the time it takes for the bird to fly determines the shape of the egg.
Researchers at Princeton University in the United States collected 49,000 photos of birds from different species of birds and compared them with their parents' weight, nest type, and wing shape.
Two comparative studies have been found to have the greatest impact on the appearance of eggs. It was the measure of the size of the eggs, the wings of the birds, or how long and sharp the birds' wings were.
Anyone can understand that the larger the size of the egg, the greater the pressure it gets when it comes out of the body, which can change its shape.
But scientists were surprised to find out that the shape of the wing also affects the shape of the eggs.
The shape of the wing is a biological measure of how strong the bird will be and how long it will stay in the air.
Of course, the longer the bird stays in the air, the more power it needs. For example, a bird 's egg with a lot of wings is a thin and long watermelon, but the owl' s eggs are much rounder with less flapping.
The researchers gathered the information and tested this theory that had been quietly spreading since the early 1990s.
Birds with stronger wings can develop eggs more efficiently because of the more efficient body development, so that the mother bird can lay eggs more easily through narrower difficulty.
The researchers selected a biological model to test the force applied during formation of the egg in the body and found that the shape of the egg changes with the force applied.
A comparative analysis of nearly 50,000 photographs is a solid evidence, and the researchers say they will continue to do research there.
They added that more experiments should be done to prove that the biological model accurately reflects the actual situation.