Some of your bird's mannerisms may be obvious, while others may be subtle. Either way, your bird's body language can give you insight into what your bird needs and wants. Although different bird species display different body languages, the following behaviors are observed in most pet birds, some more often than others and some more prominently than others. Observing your bird's eyes, vocalizations, wings, tail, foot movement, beak, and overall posture can be very telling.
Eyes - Birds can control the dilation of their pupils. Depending on if your bird is excited, curious, angry, frightened, or aggressive, his pupils may enlarge and shrink rapidly. This display is called "flashing" or "pinning." When taken into context with your bird's immediate environment and body posture, this behavior can offer insight into your bird's current emotions.
Wing Movement - Birds use their wings to communicate in addition to fly. Similar to vocalizations, how your bird flaps, flips, or droops his wings may mean something different. Your bird may flap his wings as exercise, to get your attention, or because he is happy. If your bird flips his wings, he might be angry or in pain, or simply fluffing his feathers. Wings that droop, however, may indicate your bird is exhausted (after play) or, worse, ill.
Tail Movement - Similar to the tails of other animals, a bird's tail is also used to communicate happiness, aggression, or strength. Like dogs, for instance, your bird wags his tail when happy. He fans his tail feathers to show his strength and possible aggression. If your bird bobs his tail after strenuous exercise, he may be catching his breath. But if your bird bobs his tail while breathing hard without exercise, it may be a sign of respiratory problems and your veterinarian should be consulted.
Leg and Foot Movement - Though not used to communicate as much as other body parts, your bird's leg and foot movement is interesting. Some birds, especially cockatoos, will tap their feet as a sign of dominance. Other birds may feign leg weakness when you try to return them to their cage after an involved and interactive play session. It is, however, simply a form of resisting the end of their play time.
Beak Movement - Though used to forage, groom, and play, your bird's beak is also a communication tool. Beak grinding, for instance, is often a sign of contentment, while a single click of the beak may be a form of greeting you, and a series of beak clicks may be a warning to stay away.
Body Posture - How your bird holds himself may tell you the most about his current disposition. Some postures, such as a relaxed, but attentive body, means your bird is happy and content. Others, such as a rigid, but attentive body, means your bird is stating his ownership of the immediate territory. Many body postures, however, combine with other mannerisms to key you in on how your bird feels and what he needs or wants.
Vocalizations - Birds are highly vocal in both the wild and the cage. Depending on the sound, your bird may be trying to communicate a variety of emotions. Sounds such as singing, talking, chattering, or whistling often signify your bird is happy, healthy, and content. Other sounds are used in different ways, often depending on your bird's environment and posture. Purring, for example, could mean he is either content or annoyed. Still other sounds, such as "growling," signal aggression towards something of which your bird does not approve.
Like humans and many animals, birds use their body and body parts to convey messages to others. Some of these messages are subtle and, when combined with different gestures, may mean different things. But regardless of whether your bird uses human words or not, how and when he moves his body is every bird's main form of communication. It would be wise to listen, especially when your bird seems to be saying nothing at all.