Author's preface to "Birds and Men" (Collins, New Naturalist series, 1951)
When the Editors invited me to write this book, they offered me an opportunity to complete a picture of the impact of civilisation on our bird life for which I had drawn a first sketch in "Birds in England" over twenty years ago. Here was a chance to trace the shaping of our towns and countryside and the life-histories and ecology of their more characteristic birds. In taking this opportunity I soon found that far too little is yet known to allow anything approaching a complete picture to be drawn, although it is true that enough has been learnt recently to give us a much better idea of the subject.
What I have done here, therefore, amounts to no more than a fuller and more mature sketch from a new angle, emphasising salient features and a certain amount of detail, and bringing out some of the gaps remaining to be filled in our knowledge of the facts and of underlying forces. I have not hesitated to look forward as well as back, since nothing is more misleading than to accept the assumption that the particular pattern of bird life which we see in any given place at any give time is in any way more normal or enduring that the different patterns which have just preceded and will soon follow it. For a similar reason I have tried to describe bird life in Britain against the background of the distribution and habits of the same birds in other lands, not exhaustively but as a reminder that the birds we see here also live in other countries on different terms. To begin to understand, say, a wren, we need to take not only a wren's eye view of the nearest heap of brushwood but a broader sweep of vision over the thin brown line of wrens which girdles the northern world from Iceland and Ireland through Europe, Siberia and North America to the Gulf of St. Lawrence.