When it comes to bird eggs, ostrich eggs are not average; they are the largest eggs laid by any living bird. This shouldn't be surprising considering that ostriches are the largest living birds. What might be surprising though is that ostrich eggs are the smallest among all bird eggs in relation to the size of the adult bird.
Average Size and Weight
According to the San Diego Zoo, ostrich eggs average 6 inches in length and 5 inches across, and weigh about 3 pounds. An ostrich egg is comparable in size to a cantaloupe, and comparable in weight to two dozen chicken eggs.
Ostriches live in herds of 5 to 50 and are led by a single alpha hen. Individual ostriches lay an average of 7 to 10 eggs at a time. A territorial male scratches the ground to create a depression that is used for a communal nest, and mates with the alpha hen. The alpha hen lays her eggs in the center of the nest; after which, other hens lay their eggs. Communal nests, called dump nests, can hold up to 60 eggs at a time.
The territorial male and the alpha hen take turns incubating the nest. To conceal the nest, the hen takes the day shift because her drab coloring blends in with the sand, and the male takes the night shift because his black coloring can't be seen in the dark. The eggs generally take 35 to 45 days to hatch, and when the chicks are born, they can be as big as chickens.