The only humanoid character to ever appear amongst the animals, Dave the Human was a puppet version of Muppeteer Dave Goelz. Footage material of 'real' humans in their natural habitat showed a day in the life of Dave Goelz and his family.
Since Goelz performed Stinky, his puppet was performed by Bill Barretta. Interestingly, Stinky is the one who insults Dave the Human at some points.
Goelz spoke of Barretta's performance;
“Bill came along, and he's a great observer of behavior, and so he realized there is a certain thing that I always do, which is when I get really excited about something, I say "Yeah!" and throw my fists up in front of me. He walked in with the character and started doing that and it cracked everybody up because it was spot on. It was really an inside joke for us, but it worked out nicely.”