As birds flying; rather, as birds hovering, or fluttering, ever their young, to protect them. A second simile, expressive of tenderness, as the former one was of power and strength. Defending, also, etc.
Translate, defending and delivering, passing over and preserving. In the word "passing over" there seems to be a reference to the institution of the Passover, when the angel, sometimes identified with Jehovah himself, "passed ever" and spared the Israelites.