ostrich eggs are the largest of all eggs (and the yolk is the largest single cell), but they are actually the smallest eggs relative to the size of the adult bird. — on average they are long, wide, and weigh , over 20 times the weight of a chicken egg. the eggs are incubated by the females by day and by the males by night. this uses the colouration of the two sexes to escape detection of the nest, as the drab female blends in with the sand, while the black male is nearly undetectable in the night. the incubation period is 35 to 45 days.