As a cage is full of birds— A trap-cage. כלוב kelub, comes from כלב keleb, a dog; and this name was undoubtedly given to the trap-cage, because it served the same purpose as a dog in assisting to catch game. That sort of trap-cage also seems to be alluded to, in which tame birds are put to hop and fly about as a decoy to others.
Related Commentaries of Jeremiah 5:27
Jeremiah 5:27
27 As a cagec is full of birds, so are their houses full of deceit: therefore they are become great, and waxen rich.