The Cambridge Manuals of Science and Literature

THE MIGRATION OF BIRDS

CAMBRIDGE UNIVERSITY PRESS
London: FETTER LANE, E.C.
C. F. CLAY, Manager

Edinburgh: 100 PRINCES STREET
Berlin: A. ASHER AND CO.
Leipzig: F. A. BROCKHAUS
New York: G. P. PUTNAM'S SONS
Bombay and Calcutta: MACMILLAN AND CO., Ltd.

All rights reserved

With the exception of the coat of arms at the foot, the design onthe title page is a reproduction of one used by the earliest knownCambridge printer, John Siberch, 1521

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PREFACE

Any attempt to elucidate the problems connected with the Migrationof Birds must, in the present state of knowledge, contain some theoryand speculation, but the diligent observations of an army of carefulworkers yearly add facts, which though they may appear insignificantwhen considered alone, tend in the aggregate to confirm or repudiate theconclusions of past workers. I have endeavoured to bring together someof the more important theories, and to give prominence to ascertainedfacts; I have also striven to check desire on my own part to wander intorealms of pure speculation, though conscious that I have not alwaysevidence to support my suggestions.

The numbers in brackets ( ) in the text refer to the books or papersmentioned in the list at the end of the volume, which is in no ways anattempt at a full bibliography. I have quoted freely from the works ofpast and living ornithologists. To these I offer apologies if I have [vi]misconstrued their arguments, and acknowledge my indebtedness to thosewhose observations or writing have given me light. In particular I tender thanksto Mr Wells W. Cooke for his permission to reproduce the maps facingpp. 76, 78, 80. I have found his writings and those of Herr Otto Hermanand Mr W. Eagle Clarke especially valuable. Mr Eagle Clarke's longlooked-for book on Migration is, as I write, still in the press; hadmine been more than a manual I should have hesitated to publish untilhis had appeared.

T. A. Coward.

Bowdon, Cheshire,
4 November 1911.

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CONTENTS