How do I change an animal's name?

Go to your animal collection album by choosing the book icon in the bottom right corner to see pictures of the Zoo animals. Some of them are already housed in your Zoo, while the rest of them will be unlocked later.
Select the photo of the animal whose name you'd like to change.
You can enter a new name or assign a random name in the pop-up window.
Choose the check mark to confirm the new name.