She treats her young harshly, as if not her own, with no concern that her labor was in vain.
The ostrich is a wonderful animal, a very large bird, but it never flies. Some have called it a winged camel. God here gives an account of it, and observes, I. Something that it has in common with the peacock, that is, beautiful feathers (Job 39:13): Gavest thou proud wings unto the peacocks? so some read it. Fine feathers make proud birds.
Commenting on Job 39:13-18
She is hardened against her young ones, as though they were not hers,.... Hence said to be cruel, Lam 4:3; not against the young ones she hatches, for Aelianus (c) reports her as very tender of her young, and exposing herself to danger for the preservation of them; but being a very forgetful creature, having laid its eggs in the sand, where it leaves them...
On a slight noise she often forsakes her eggs, and returns not, as if she were "hardened towards her young." her labour--in producing eggs, is in vain, (yet) she has not disquietude (about her young), unlike other birds, who, if one egg and another are taken away, will go on laying till their full number is made up.