The first occurrence.
And God created the great sea creatures, and every living creature that creeps, with which the waters swarmed, with regard to their kinds, and every winged creature with regard to its kind; and God saw that it was good. Gen 1:21
The primitive root.
kaph כ ך = open palm, thus bend, open, allow, tame
nun נ ן = seed, thus continue, heir, son
pey פ ף = mouth, thus open, blow, scatter, edge
The story: The opening of the wing covers (kaph, in the sense of the father’s open palm covering the head of his son when conferring the blessing) the offspring (nun) with open mouths (pey), i.e., baby birds.