If we grant that birds possess highly-developed imitative faculties and tenacious memories, with a discriminating power which enables them to adapt certain habits of life to surrounding conditions, even this fails to explain a great deal. Supposing it is the secret of their beautiful nest-building, the house sparrow adopting trees to nest in where the houses are built of brick and lack crevices, or the falcon deserting its usual high inaccessible crag and nesting on the ground; it cannot possibly account for a young duck taking the water directly it has left the shell, or the habit of young plovers, snipes, grouse, and other birds crouching flat when danger is overhead even as soon as they are hatched. A stronger point still is migration, for birds cannot return to their old haunts by a memory of landmarks, as pigeons do even in their longest flights, for they fly over immense bodies of water and traverse vast tracts of land by night, on wings the length and strength of which have been specially developed for such long flights. Some fly across great stretches of country, yet are never seen except at the points from which they start and finish their flight. Neither can these journeys be performed always under the guidance of leaders, for all migratory birds do not travel in flocks. I will endeavour to point out how Nature has solved the problem of preservation; and it is equally interesting whether by the self-governed action of the bird, or the blind following of an impulse known only as instinct. Because we are unable to find any protective colouration in the plumage of a bird, its eggs or nest, we must not conclude that such peculiarity is a mere accident or useless decoration, for it either serves some wise end unknown to us, or has done so in far past ages, and is perpetuated because its possession is not distinctly harmful, and may at some future date be again called into requisition against danger. The extinction of nearly all birds whose existence is reasonably well-known has not been due to natural causes, but to man or the influence his civilisation has introduced. Nature never made such a mistake as the introduction of rabbits and sparrows into Australia. They are two potent forces turned loose into practically unrestricted space, without any of their natural limiting influences.