34 



USE OF THE KEYS. 



each step test your decision by reading the brief diagnoses of orders 

 and families. In this way you may readily place your bird in its 

 proper family. 



The Keys to Species. If a bird always wore the same plumage it 

 would be a comparatively easy matter to place it in a certain section 



Q 



Fio. 3. Spotted (a), streaked (6), barred (c), and margined (d) feathers. 



of a key and keep it there. But, unfortunately, not only are the males 

 and females of the same species frequently quite unlike, and the young 

 different from either, but their plumages may vary with the season. 

 Tims, you see, a bird's color is a most uncertain quantity. An individ- 

 ual of a given species may not only wear two very different costumes, 

 but, in doffing one for another, he does it gradually, and in the mean- 

 time appears in changing or transition plumage. 



For this reason it has been customary to base keys on only adult 

 males. Such keys do very well in the nesting season, when birds are 

 in song, and when males constitute probably nine tenths of the birds 

 one sees. But at other times of the year young birds outnumber the 

 old ones, and the adults themselves may lose their breeding plumage 

 and wear quite a different one. I have, therefore, attempted to make 

 keys which will identify a bird in any plumage. To do this it was 

 necessary to use many more specimens than there were species. For 

 example, the key to our some 40 species of Warblers is based on 110 

 specimens representing as many phases of pluma-rc. 



With identification as the sole end in view I have, in the keys, 

 abandoned all attempts to follow the current system of classification, 

 and. taking color as the most tangible character, have to a great extent 

 arranged the species on this character alone. The result, from the sys- 

 t-, ii;:i!ist's standpoint, is most unnatural. Species of different genera 



