Despite the wide notion that ostriches bury their hands in the sand, this is just fiction.
This tale originates from the fact that the male ostrich will dig a large hole (as large as 6 to 8 feet wide and 2-3 feet deep) in the sand for the nest and/or eggs. Predators cannot see the eggs which gives the nest a bit of protection. The hen and rooster takes turns setting on the eggs and because of the indention in the ground, mainly just blend into the horizon. All birds turn their eggs (with their beak) a few times a day during the incubation period. From a distance, it appears as though it has his/her head in the sand.