The smallest bird egg belongs to the hummingbird and is the size of a pea. The largest bird egg, from which the ostrich hatches, is the size of a cantaloupe.
A bird’s eye takes up about 50 percent of its head; our eyes take up about 5 percent of our head. To be comparable to a bird’s eyes, our eyes would have to be the size of baseballs.
Source: mspca angell, Kindness and Care for Animals