Who is Head Man of the Birds from The Trumpet of the Swan and what is their importance?

The Head Man of the Birds made the first deal not to clip Louis's wing. He also makes the deal for Louis to play a concert every Sunday afternoon. When Serena comes to the zoo, the Head Man has to make another deal with Louis so Serena would not have her wing clipped. The Head Man talks to Sam and is able to make a deal with him in Serena's favor.