The opening scroll from The Maltese Falcon is, sadly, completely made up. There was no real Maltese falcon, although the idea may have come from another magnificent bird, the Kniphausen Hawk, which was made in 1697 for a Count of the Holy Roman Empire.
The Kniphausen Hawk certainly fits the bill – or should that be beak? – being made of precious metal and encrusted with rare jewels. It’s silver rather than gold, though, and a good deal more lively than the falcon. The Kniphausen Hawk is part of the collection at Chatsworth House, and there’s a photograph of it here.
Several prop falcons were made for the movie, and these are themselves worth a fortune. There are two lead falcons known to exist, one of which sold in 1994 at auction for $398,500, and there’s at least one original prop made of resin. It’s often possible to tell which version is on screen at any given moment, as long as somebody’s holding it: the lead falcons weighed more than 20 kilos each!
Aside from the authentic prop falcons, there’s also a healthy trade in replica falcons of varying quality. Of these replicas, the most accurate one-off must be the one made by propmaker & Mythbusters co-host Adam Savage. He discusses the process, and a great deal more about the history of the falcon prop, in the video below. (First he talks about reconstructing a Dodo skeleton. It’s very interesting in its own right, but skip to 6:25 if you’re in a hurry and want the falcon story.)