Читать книгу Bird Senses - Graham R. Martin - Страница 28

Early attempts to quantify the sensory capacities of birds relied upon anecdotal observations of behaviour, or at least behaviour that was not well controlled. These attempts typically also involved imprecise control of a testing stimulus, or perhaps no control at all, but relied on natural situations. This approach led to some rather over-the-top estimates of sensory abilities. These include some fantastic claims for the visual sensitivity of owls and the visual acuity of raptors, and even the wholesale denial that most birds have a sense of smell.

The use of well-controlled stimuli and systematic techniques for controlling behaviour now give quite different insights into the information available to birds. For example, we now see more modest estimates of visual sensitivity and a growing awareness of the importance of olfaction in a wide range of bird behaviours. Unfortunately, the results of the older anecdotal observations still linger in the literature and on the internet, and many people seem reluctant to give up old assumptions about ‘super-senses’ that these early studies seemed to support.

It is not difficult to understand why people favoured old interpretations based on anecdotal observations. They often squared with everyday observations of our own sensory capacities, and they often built upon myths and legends about the place of animals in the world and ideas about what it meant to be human. With a general decline in the potency of those myths and legends (including mainstream religious ideas) we are generally not so sure about what it means to be human or of our place in the world. More careful assessment of what humans can see, hear, smell, etc., compared with knowledge of these sensory abilities in other animals, now plays its part in helping to understand our position in nature.

Finding out about our own senses has proved to be a difficult task, requiring careful procedures and controls. It is more difficult to apply those techniques to ask the same questions in similar ways of non-human animals. It seems relatively easy to ask another person what they can see, hear, smell, or feel, but even then we want to know just how carefully controlled were the stimulus conditions. We also need to know whether the person was fully attentive to the task, especially if the task became increasingly difficult as the stimulus got closer to the limit of a sense’s abilities. Did the person really try to see the finest detail? Hear the faintest sound? Or did they give up on the task before reaching the limits of their performance?