Bird anatomy Birds have a four-chambered heart, in common with mammals, and some reptiles (mainly the crocodilia). This adaptation allows for an efficient nutrient and oxygen transport throughout the body, providing birds with energy to fly and maintain high levels of activity. A ruby-throated hummingbird's heart beats up to 1200 times per minute (about 20 beats per second). Many birds possess a muscular pouch along the esophagus called a crop. The crop functions to both soften food and regulate its flow through the system by storing it temporarily. The size and shape of the crop is quite variable among the birds. Members
Human uses of birds death, being sacred, or being used in heraldry. In terms of entertainment, raptors have been used in falconry, while cagebirds have been kept for their song. Other birds have been raised for the traditional sports of cockfighting and pigeon racing. Birdwatching, too, has grown to become a major leisure activity. Birds feature in a wide variety of art forms, including in painting, sculpture, poetry and prose, film and fashion. Birds also appear in music as well as traditional dance and ballet. In certain cases, such as the bird-and-flower painting of China, birds are central to an artistic genre. Culture consists