Other adaptations include a light skeleton with hollow bones and a large keel-shaped breastbone providing attachment for the powerful flight muscles. Birds have good eyesight and colour vision and most are active by day. Through flight, they have managed to colonize almost every available terrestrial, freshwater, and marine habitat. Social behaviour plays an important part in the life of birds, which show complex patterns of behaviour in territorial and courtship displays, nest building, egg incubation, and care of the young.
Birds are of great economic importance to man.
Certain diseases, notably psittacosis, are transmitted to man by birds. See also ornithology . Oxford Paperback Encyclopedia 5. All rights reserved.