Fact Checker Footnote:

Three years later, the twins became Brassmonkey Bay's assistant Zookeepers.  They loved all the animals but their favorites were  Chilli Koala, Jock Cockatoo, Liberty Wombat, Solomon Penguin and Pilfer Possum. 

What does it take to make a small Zoo like Brassmonkey Bay's a success?  Pax and Pip know it isn't the number of animals that count. It's their star quality! 

Pip and Pax wanted to help endangered animals

so They volunteered at a Zoo...