Colour helps you see things. But ma

Colour helps you see things. But man and some monkeys and apes (猿)are the only mammals (哺乳动物) that can see colour. To any other mammal, such as the dog, the world looks like a black-and-white photo. Dogs hunt mainly by listening and sniffing (闻). Like other animals, dogs see best when things move. The animals they hunt seem to know this. A hunted rabbit or deer will “freeze”. Then the dog may not see it at all. Birds can see colour. They need to, because they fly and need to find places to land．Colour helps them judge distance and shape. In this way they are able to catch bugs (昆虫) in the air or to light on branches. Some birds see things even better than you do. The birds that eat bugs can see them from far away. And even a very young bird can see a hawk high in the sky. So sharp eyes and a sense of colour help birds find food and also help them find where their enemies are.