Orientation of Birds

systematic studies on orientation in birds were made possible by the ‘homing instinct’ exhibited by so many species. Birds are caught at a time when they show an attachment to their territory, especially during the nesting season. They are taken to some spot, released, and the percentage of returns is recorded. The distance can be varied, and the direction, as well as the method of transporting them, and then the influence of climatic and other factors on their ability to find their way home can be studied. These experiments have shown a wide variation in ability to home, and three types of homing behaviour have been identified. C In the first type, birds methodically explore the area in which they are released until they pick up some familiar feature, and then they quickly find their way back to the nest. Such birds possess a highly developed visual memory, as experiments with pigeons have shown. Domestic pigeons have been trained to peck at a certain point on an aerial photograph, with a system of rewards, and four years later the birds were still able to respond to this training when placed on the aerial photograph. Birds’ eyes have a power of resolution two to three times greater than ours, enabling them to pick up very…