'Birds of the Air' in the Bible

A sower went out to sow his seed, and as he was sowing, some fell by the way-side, and was trodden down, and the birds of the air devoured it.

It is like a grain of mustard-seed, which a man took and sowed in his garden, and it grew, and became a great tree, and the birds of the air lodged in it's boughs.