The mint workers polished the dies to the point where low relief details were eliminated. I really don't understand why these are so popular, widely collected, or sell for as much as they do. The same thing caused the so-called "three legged" buffaloes and the "broken nose" on numerous other series.
It's because they represent extraordinary circumstances, expedients the Mint would not normally take. You wouldn't have to polish the feathers off of a die if they gave you enough dies. I can only imagine the looks of dismay at Denver once they realized just how far they had to push the few Cent dies they had. We value coins for their Mint State perfection, yet it's the mistakes and extremities which we give the nicknames.
