About the zoo fences: it's true they're pretty low when looked at from the visitor's side, but you have to know that usually there's a trench a the animals' side so they can't actually reach the fenced. Also, the ground over there is usually much lower as well.
Now, it's not really clear whether that's also the case here, moreso because of
Spoiler:Gabe's attempt to call them over. He wouldn't be able to reach them even if they did listen
. So that might just have been changed in order to introduce this particular puzzle.
