PREFACE v 



the Genus generally providing a convenient division, the species in it being com- 

 pared in respect to each class of activities, e.g. courtship, nesting habits, feeding 

 habits, and so on. But rigid uniformity in arrangement has not been attempted. 

 All the Finch Genera, for instance, owing to the marked similarity in the general 

 habits of their species, are taken together. The same applies to the swallow, 

 house-martin, and sand-martin, also to the jay and the magpie. On the other 

 hand, the genus Corvus is divided into groups, in order to avoid unwieldy 

 sections. Each writer has been left to arrange and treat the matter within 

 each section of a chapter in the way best suited to his style and temperament, 

 thus avoiding cut-and-dried uniformity with its resulting aridity. Any incon- 

 venience that this course may have is met by the index, and to some extent by 

 setting apart and arranging systematically the information that is most often 

 needed for reference. This is placed at the head of the chapter under the title of 

 Preliminary Classified Notes. 



Preliminary Classified Notes. These contain not only the information 

 needed for reference, but certain classes of fact which lend themselves better to 

 systematic or statistical than to literary treatment. Under the same head are 

 placed the facts relative to the migration and distribution of the species, for these 

 are subjects that can only properly be dealt with by specialists. All three categories 

 are arranged on a uniform unvarying plan under the head of each species, as 

 follows : 



1. Description of the male, female, and young, and their seasonal changes of 



plumage. 



2. Distribution. 



3. Migration. 



4. Nest and eggs. Under this head is given a description of the nest, its site, 



the eggs, and information as to the number of eggs, the period at which 

 the species begins laying, the share of the sexes in incubation, the period 

 of incubation, and the number of broods. 



5. The food, both of young and old, and the share of the parents in feeding the 



young. 



6. The period of the year during which the species sings. 



Supplementary Chapters. In addition to the chapters on the habits of 

 each Family and the Preliminary Classified Notes which form part of them, there 

 will be found at the end of the book certain supplementary chapters dealing with 

 special points. 



The first of these contains descriptions of species which are almost extinct 



