There are several big birds such as Ostriches and Emus who cannot fly because they lack a keel (an extension of the breastbone) where wing muscles attach.
Flapping the wings uses a lot of calories, which is why many birds mainly glide (use updrafts from cumulus clouds or mountains).
Flight is one way to get away from predators, but being big and fast and having a good kick also works.
The largest birds are ostriches who are fast runners (70km/h) and can be up to2.8m tall.
Many eggs in a nest are advantageous because predators can’t steal all of them, some of the eggs will “survive”.
When ostrich chicks emerge from the egg they are already able to care for themselves.
Ostriches cannot fly but male ostriches do have penises which is very unusual for birds!
Only about 3 percent of all bird species have penises. Ostriches is one of them:
But Ostrich penises are hardened with a bodily fluid (called lymph), not blood!