4 Days After People: Electric fences all fail causing many animals that are trapped there to escape. The animals in cages will either starve, try to break out by using their strength or use tools to get out of there. The fish and jellyfish in the aquariums section of the zoo however will all die from either lack of food, less oxygen or predators that had escaped from their cages.
120 Years After People: The Skyfari gondolas fall from corrosion. The gondolas fall into the towers and pull them down. The escaped zoo animals are the only ones to witness it.
1,000,000 years after people: African lions now have evolved over hundreds of generations into a new type of American lion. The same happens with other animals, for example elephants, that form American elephants.