Dumb Creatures by Jeanne Willis
Tom can hear. He can think. He just can't speak. But that doesn't mean he hasn't got anything to say ...Tom's favourite place is the zoo. He enjoys sharing the word-less world of animals and, just by watching them carefully, he can tell whether they're happy or sad, hungry or hot. But, talking to animals takes on a whole new meaning for Tom when he discovers that Zanzi the female gorilla can use sign language, and when Tom discovers Zanzi's baby is stolen, he decides it's time to speak out for animal rights. But with all the adults around him too busy yelling and shouting at each other to really listen, will anyone hear him?