How BIRDS ARE NAMED 



names (binomial) to our eastern bird, the former being no more subspecies 

 of the latter than the latter is of the former. In other words, to continue to 

 apply only generic and specific names to the Eastern Robin would imply 

 that it was a full species, while the use of a trinomial for the Western or the 

 Southern Robin shows them to be subspecies. As a matter of fact we know 

 that there is but one species of true Robin in the United States, consequently 

 in accordance with the logical and now generally accepted method, we apply 

 to that species the name Planesticus migratorius, and this is equally applica- 

 ble to Robins from east, south or west. When, however, we learn that the 

 Eastern Robin is not a species but a subspecies, we repeat the specific name 

 by which it was made known and call it Planesticus migratorius migratorius^ 



It may be asked, Why give names to these geographical races? Why 

 not call Eastern, Western and Southern Robins by one name, Planesticus 

 migratorius, without regard to their climatic variations? 



In reply, two excellent reasons may be given for the recognition of sub- 

 species by name; first, because in some cases they differ from one another 

 far more than do many species, when it would clearly be inadvisable to apply 

 the same name to what are obviously different creatures. For example, it 

 has lately been discovered by Mr. E. W. Nelson that the small, black- 

 throated, brown-breasted, Quails or Bob-whites of southern Mexico, through 

 a long series of intermediates inhabiting the intervening region, intergrade 

 with the large, white-throated, black-and-white breasted, Bob-white of our 

 northern states. It would be absurd to call such wholly unlike birds by 

 the same name, nor could we give a full specific name to the Mexican Bob- 

 white since at no place can we draw a line definitely separating it from the 

 northern Bob-white. Furthermore, the use of only two names would conceal 

 the remarkable fact of the intergradation of two such strikingly different 

 birds; a fact of the first importance to students of the evolution of species. 



For much the same reason we should name those birds which show less 

 pronounced variations, such as are exhibited by the Robin. Here we have 

 a species in the making, and in tracing the relation between cause and effect, 



