Mr. Popper's Penguins by Richard and Florence Atwater

When Mr. Popper received a mysterious package from Antarctica he was delighted to find that it was a penguin. But when the Penguin, newly named Captain Cook, becomes lonely, they acquire a second penguin that just happens to be a female. Pretty soon, there are eggs, ten of them. For fun, the children, Bill and Janie, teach the penguins tricks such as climbing up ladders and pretending to fight, and for a while, everyone is happy. After a little bit, though, the penguin’s food starts to become too expensive and the threat of needing to get rid of them suddenly becomes very real. All the Poppers have gotten attached to the birds, however, so Mr. Popper is determined to keep them. One day, watching the Penguins parade around the house, he realizes that they would be good performers, and so when the Marvelous Marcos don’t show up at the circus, the Birds fill in, and so their careers begin…