178 Bird -Lore 



But, after all this work, we shall keep finding birds mixed together that 

 are quite unlike each other. By sorting over the different genera in each 

 family, we shall at last get single kinds of birds, or species, as they are called. 

 However, as we shall see later, even one kind of bird may vary much in differ- 

 ent climates and localities,— so much, indeed, that it has been thought best 

 to give still another name to each one of the varieties of a species. Accord- 

 ingly, we find the smallest pigeon-hole of all marked subspecies. 



Now to illustrate all this, take the common Song Sparrow, which is found 

 quite generally throughout North America. It is a species which varies so 

 greatly in different places and in different climates that at least twenty 

 subspecies of it are known, each looking like a Song Sparrow, but no two 

 of which are exactly alike. 



Along with the Song Sparrow are two other species, Lincoln's and the 

 Swamp Sparrows, quite similar in general appearance. For convenience, these 

 three species are placed together in one genus. But there are hundreds of 

 species of Sparrows, to say nothing of Finches, Grosbeaks, Crossbills, Long- 

 spurs, and other seed-eating birds, all so much alike in habit and structure 

 that the various genera to which they belong seem to come naturally into a 

 great family group. This family, like a large number of other families, is made 

 up of birds which have feet enabling them to perch on a support. Taken all 

 together, they are easily recognized as perching-birds, belonging to the same 

 order. 



Now when all the different orders of birds in the world are put together, 

 we have just birds in a class by themselves, as distinguished from all other 

 animals and plants which are each classified in a similar manner. 



One cannot learn a table of classification in the same way as a table of 

 weights or measures. It would be extremely handy if one could commit to 

 memory such a table, say, as this: 



20 Subspecies make a species. 

 10 Species make a genus. 



5 Genera make a family. 

 3 Families make an order. 



21 Orders make a class. 



No, this will not do, for nearly every order has a different number of families, 

 and nearly every family, a different number of genera, and so on through the 

 entire list. These relationships can better be learned out-of-doors than by 

 rule of book, provided the observations made are pigeon-holed in a practical 

 way. By making a simple table of classification to "carry in the head," it 

 becomes easy to recognize birds by their form, habits, food, flight, voice and 

 general appearance, rather than by plumage alone. When the student learns 

 to observe in this way, classification becomes an alphabet by means of which 

 natural objects reveal their relations to each other. 



Coming now to the table of thirty representative species, that we hope 



