PREFACE 
In view of the fact that over 10,000 species of birds are known to inhabit 
the earth today, it is not strange that many of them are almost unknown, 
even to bird experts. Years of travel and painstaking study would certainly 
be necessary if any one individual were to try to list even the major charac¬ 
teristics of every species of feathered creature in North and South America, 
Europe, Asia, and the Indo-Australian and Polar regions. 
The editors of BIRDS OF THE WORLD have not attempted to de¬ 
scribe all birds existing today, or even to list them. This book is not intended 
to be a field key to birds on the wing, or a dictionary of every known 
species. Great care has been taken, however, to include birds which are truly 
representative of the principal orders, typical of their kind, and, above all, 
interesting in themselves. 
Birds, after all, are not all of a kind. The difference between a wood¬ 
pecker and an ostrich, to take an example at random, is fully as great as 
the distinction between two such mammals as a monkey and a mouse. 
Actually, the only outstanding characteristic which all birds have in com¬ 
mon is their feathers. And even their feathers are not put to the same 
uses. The wing feathers of some birds are used for flight; others, like the 
penguin, don’t fly at all, but do use their wings with equal skill in swimming. 
From the strictly scientific point of view, birds are really “glorified 
reptiles,” and they still possess many of the characteristics of their reptilian 
ancestors. They lay eggs, like their forefathers, and the scale-like skin on 
their feet and legs is a feature which birds still have in common with many 
of their crawling cousins. Feathers themselves, in fact, are really modified 
scales, and they are moulted occasionally just as snakes shed their skins. 
In many ways, however, birds can be proud of the progress they have 
made from their lowly beginning. Even man, who only recently learned to 
fly after hundreds of years of trying, has not been able to make an airplane 
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