Howler Monkey's have been known to be very loud, they may be the loudest in a specific zoo that contains Howler Monkey's but I am unsure about the general loudest animal in the zoo.
howler monkey
a chimpanzee who is loud by nature
lion
lion?
Lion
A lion roaring.
monkey, elephant, giraffe
elephants? i dont know why does it matter?
I think it's a elephant.
Humans.
Well It's how you hear it. To me I would it is the elephant but if you are right next to a lion it may be loud.
elephant
The lion is often considered the loudest animal in the zoo. Its roar can be heard up to 5 miles away.