Through birds' eyes: insights into avian sensory ecology

Sensory ecology investigates the information that underlies an animal's interactions with its environment. A sensory ecology approach provides a framework in which to investigate a wide range of topics in ornithology. This review provides a range of examples of this approach. Discussed are some of the more general principles which apply with respect to the ways in which information from different sensory systems may complement each other, or information is traded-off within a sensory modality in the achievement of particular tasks. The emphasis is upon the task of foraging, but other behaviours, such as locomotion and predator detection, are also addressed. Examples discussed consider: (1) the perceptual challenges of nocturnal activity and how they are differently solved by information from different sensory system in owls, kiwi, oilbirds and penguins; (2) the use of tactile information in foraging and how this interacts with visual information in probing birds, and in skimmers; and (3) the visual information used to guide stealth foraging in herons, and how vision is influenced by the filter feeding techniques of ducks and flamingos. In addition, two case studies are discussed. These explore: (a) the restrictions on the information available to guide foraging in turbid waters by cormorants, and (b) the application of a sensory ecology approach to understanding why birds collide with artefacts, such as power lines and wind turbines, which intrude into the open airspace. Among the general conclusions discussed are: (1) the idea that all sensory systems are selective within their own modality and that the range of information that is available to a particular species have been tuned to particular perceptual challenges through natural selection; it is also argued that this tuning can take place at the individual species level such that there may be key differences in sensory information even among birds in the same genus; (2) sensory systems detect only a small part of the total information that is available in the environment; no species has available to it all the information that is potentially available in its environment; in essence, all species share the same planet but live in different worlds that are dictated by the information that their sensory systems extract from the environment; (3) there may be complex and subtle trade-offs between different types of sensory information; and (4) the overall conclusion is that the world through birds' eyes is quite different from the world as seen through human eyes but there are many different "bird eye views".