String on the falcon / the glove?

Did anyone else notice a string when the falcon lands on the glove of Jack Palance?
First I thought it's tied to the falcon, but on a closer look it seems to be fixed to a hook on the glove!

A means to prevent the falcon from flying away must be tied to the falcon itself. Another possibility would be an aid for the falcon to let him know where to land, but in this scene Palance has already food in his glove to attract the falcon.

So what's the real purpose of this string?