By Graham Martin
Pelagic Publishing, 2021
Pbk, 270pp; numerous colour images
ISBN 978-1-78427-2166; £29.99
In the early 1900s the Estonian biologist Jakob von Uexküll came up with the extraordinarily novel concept that all animals live in a subjective world – an Umwelt – where only certain things matter. The Umwelt of a nocturnal owl, for example, is very different from that of the flightless kiwi, which is also nocturnal, and while the owl relies mainly on vision and hearing, the kiwi has poor eyesight and depends on touch and hearing. Birds (and all other animals) perceive their world through their sensory system, hence the subtitle of Graham Martin’s excellent and extremely comprehensive book.
Martin has spent most of his academic career studying the senses of birds, focusing mainly on vision and hearing, especially in nocturnal species. He has published prolifically on this topic and his previous books include Birds by Night (Poyser 2010) and The Sensory Ecology of Birds (Oxford 2017). The present book, aimed principally at a more general audience than the latter, covers avian vision, hearing, smell, touch and taste as well as the way birds perceive the earth’s magnetic field (so important in navigation and migration). The section on vision is perhaps inevitably – given its importance to both birds and Martin – the most detailed and intriguing, covering eye design, position of the eyes on the head, visual fields and binocular vision. There are two chapters on birds in the dark, and one on birds underwater. The slightly less well-studied senses of hearing and smell together get a chapter, as do touch and taste. It would have been interesting to know whether Martin thinks that birds experience emotions.
With numerous attractive colour photographs and diagrams throughout, this is an attractively produced book, but I was left wondering whether it was the author’s or the publisher’s decision not to include any references? Without these, anyone wanting to follow up on a particular topic will struggle. And, although we are told that ‘all statements are well supported by published material’ – which I am sure is true – in an age of increasing misinformation, I suspect that many readers would rather have had the references.
Studies of the sensory ecology of birds have been eclipsed in the last few decades by the huge volume of research on their behaviour and ecology, yet understanding how birds perceive the world – their world – is essential for a complete appreciation of what it must be like to be a bird. This is not simply of academic interest; it also has important conservation implications. Around 100 million birds are killed each year by collisions – with aircraft, power lines, communication masts, oil rigs, fishing nets, buildings and windows. That birds function in a completely different visual world from ourselves will be clear after reading Martin’s book, and that’s what the engineers who design wind turbines should do, to reduce the risk of collisions. In flight many birds cannot see directly in front of them, and even for those that can, this is not the field of view with the highest resolution, and unlike a human driving a car, birds are unable to make drastic changes in their speed of travel, meaning that the rate at which they receive information as they fly is fixed – are we surprised then, that collisions are so common? Can we design structures that take the birds’ Umwelt into account?