Albert Barnes Commentary Jeremiah 8:7

"Yea, the stork in the heavens knoweth her appointed times; and the turtle-dove and the swallow and the crane observe the time of their coming; but my people know not the law of Jehovah." — Jeremiah 8:7 (ASV)

Jeremiah appeals to the obedience which migratory birds render to the law of their natures. The “stork” arrives in Palestine about March 21, and after a six weeks’ halt departs for the north of Europe. It takes its flight by day, at a vast height in the air (in the heaven). The appearance of the “turtle-dove” is one of the pleasant signs of the approach of spring.

The crane and the swallow — Rather, “the swift and the crane.”