Birds are becoming popular as pets,but unlike more common pets,owners of birds are often not familiar with the behavioral patterns of the animal which allow them to recognize what the pet needs and wants.For example,most of us can recognize the behavior a dog exhibits when he is hungry or wants attention,but how many of us know how birds go about showing the same needs?By learning about the behavioral patterns of birds,their owners can build a stronger relationship with their pets. Owners can learn how to read birds’ body language, including movements of the eyes,wings and tail. In addition, the sounds birds make can also indicate their mood, desires, and requirements. Birds’ eyes are different from humans’. While both birds and humans have pupils( 瞳孔 ) and irises( 虹膜 ), birds have the ability to control the size of their pupils by enlarging and reducing their irises quickly. This behavior is something birds may do when they are angry, interested or frightened. Birds also communicate through the use of their wings.They may lift or open their wings as a sign of happiness. But if they start opening and closing their wings,it may signal anger or pain.If birds fail to fold their wings against their body, and instead let them hang by their side,they may be ill. Birds often use their tail feathers to communicate, so an understanding of this behavior will help owners of birds.Birds may move their tail from side to express happiness. Birds may also express their happiness by other kinds of tail movement, such as moving their tail up and down. Finally, the sounds birds make are very important in communication.Birds use vocalizations( 发声法 ) to communicate with each other and with their owners.Singing is the sign of a happy bird,and many birds love to sing when others are around.Birds may also purr( 咕噜咕噜叫 ), which may indicate that they are annoyed.