Jamieson, Fausset and Brown on Job 39:13

13. Rather, "the wing of the ostrich hen"--literally, "the crying bird"; as the Arab name for it means "song"; referring to its night cries (Job 30:29; Mi 1:8) vibrating joyously. "Is it not like the quill and feathers of the pious bird" (the stork)? [Umbreit]. The vibrating, quivering wing, serving for sail and oar at once, is characteristic of the ostrich in full course. Its white and black feathers in the wing and tail are like the stork's. But, unlike that bird, the symbol of parental love in the East, it with seeming want of natural (pious) affection deserts its young. Both birds are poetically called by descriptive, instead of their usual appellative, names.