3.} 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 11'0sz 1‘0 Species—If a bird always wore the same plumage it would be a comparatively easy matter to place it in a certain section

FIG. 3.—Spotted (a), streaked (b), 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. Thus, 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 dotting 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 \Varblers is based on 110 specimens representing as many phases of plumage.

With identification as the sole end in View l 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- tematist’s standpoint, is most unnatural. Species of different genera