'Birds of the Air' in the Bible

Look at the birds of the air; they neither sow [seed] nor reap [the harvest] nor gather [the crops] into barns, and yet your heavenly Father keeps feeding them. Are you not worth much more than they?

And Jesus saith unto him, The foxes have holes, and the birds of the air have nests; but the Son of man hath not where to lay his head.

Which indeed is the least of all seeds: but when it is grown, it is the greatest among herbs, and becometh a tree, so that the birds of the air come and lodge in the branches thereof.