vi PREFACE 
have found by experience that confusion is easy or 
probable, either between birds, or nests, or eggs, a 
careful attempt has been made to set forth the 
recognisable points of difference in as clear and 
plainly contrasted a manner as possible. In the 
descriptions of the birds themselves, the aim has 
generally been to avoid a confusing heap of detail, 
and to refer, as a rule, to those salient features in 
their plumage, flight, or cries, which make 
recognition most easy. A few of the leading 
problems of bird life, such as migration, and the 
theory of protective imitation, have been touched 
upon in cases where they most naturally excite atten- 
tion during bird-study and birds'-nesting in the field. 
The coloured illustrations have, in all cases, been 
reproduced from paintings of carefully chosen and 
characteristic examples. It is hoped that the 
outline drawings, representing the typical shape 
and size of the white, unspotted eggs, will prove a 
useful assistance in identifying those often puzzling 
specimens. 
In the course of preparing the descriptions, use 
has frequently been made of Mr. Howard Saunders's 
well-known and excellent Illustrated Manual of 
