Introduction

Among the hundreds of bird nests carefully preserved in The Natural History Museum, London, is an unremarkable looking cup nest of grass and rootlets collected in New Zealand during the last century. It is the nest of the mournfully named piopio or New Zealand thrush (Turnagra capensis). The interesting thing about the nest is that the builder is extinct, a victim of introduced mammals and its own over-confiding nature. The bird itself was last observed in 1947 (Fuller 1987). Possibly no other nest of this species remains in the world. It is an enduring expression of behaviour that can no longer be seen. To touch it is to be as close to its maker as to touch a brush stroke of a Van Gogh sunflower.

The structures animals build persist through time and in their construction the world is changed for the builders and for others. They may simply be regarded as objects of curiosity or wonder but, as products of evolution, they must embody principles of the organisation of the behaviour that created them, of functional design and of the evolutionary process itself; the scientific study of them should reveal some of these principles. This is the purpose of this book and the subjects to be examined are the nests and other objects constructed by that most consistently impressive group of animal builders, the birds.