My wife works with the Los Angeles Department of Water & Power, and they run a tree program for residents of the city of Los Angeles. You are allowed something like 5 or 6 free trees, if you are a property owner. They also provide free trees to LA city parks and schools. Curious, last night we were just discussing LADWP having given free trees to the Zoo in the past, and I'm almost positive they're the source of Billy's trees.
I live only an hour and a half away from the Indianapolis Zoo, yet I have never been... Maybe I should make a trip over there this year...Most of the zoo looks quite nice