6 
INTRODUCTION • 
therefore recognize these intergrading variations due to or based upon 
geographical distribution as Geographical Races, Varieties, or Subspecies, 
the last term being now the most usual. We regard them as species in the 
making before the connecting stages binding them to the original stock 
have, owing to the increasing sterility between the variants, disappeared. 
Except in such rare cases of physical isolation as where an oceanic island 
habitat precludes continuous distribution, we take, in practice, the exist- 
ence of intergrades as the evidence of subspecific status. 
Subspecific varieties or geographic races are, therefore, divisions of 
the species, and except in special lines of work, or where special exactitude 
is necessary, are of minor importance. As these subspecies are also in many 
cases based upon points of difference perceptible to only the most experi- 
enced observers, they are mainly outside the sphere of interest of the average 
amateur observer. 
Besides these divisions of taxonomic value there are a few other 
variants that, owing to their erratic occurrence, cannot be recognized in our 
classification. These are “Albinos,” “Melanos,” and “Dichromatic Forms.” 
Albinos and Melanos are individuals suffering from an abnormal 
deficiency or superabundance of colouring matter in the skin and its 
appendages. White mice and black foxes are examples, respectively. 
Dichromatism (and its extreme, polychromatism) is the occurrence of 
two (or more) colour types normal in a species. Domestic cats in their 
various colours can be regarded as polychromatic. 
NOMENCLATURE 
Every North American bird has a common or vernacular English name 
authorized by usage and recognized by the leading ornithologists, and there 
is seldom ordinary necessity for the scientific name. However, it is well for 
all who are interested in birds to familiarize themselves with as many of 
the scientific names as possible, as they are essential in more advanced work 
and of practical use in grasping the general relationships between various 
species. They are a necessity for international scientific intercourse and 
familiarity makes them much less forbidding than they seem at first. The 
ease with which such scientific names as geranium and hippopotamus, to 
say nothing of Junco and Vireo, have glided into popular usage shows 
that they are not as difficult and awkward as they appear on paper. 
The French vernacular names have been the subject of much consider- 
ation. There is at present no generally recognized system of French com- 
mon names as there is of English ones for the birds of Canada. Such 
French names as have appeared in Canadian ornithological literature have 
applied only to a limited number of species or have left much to be desired 
from a practical standpoint. Further, they have seldom been used in the 
particular specific or subspecific sense called for by the plan of this work. 
The names used in this book represent an attempt to combine current 
usage and convenience with approximate scientific accuracy in harmony 
with universal practice. They are employed as a temporary expedient to 
serve until a system can be evolved by French-Canadian ornithologists. 
The present binomial system of nomenclature was introduced by 
Linnaeus, the great Swedish botanist, and embodied in his “Systema- 
Naturae,” the tenth edition, 1758, which is the authority accepted by 
American ornithologists. In this system each species is given a double 
name, the first term being that of the genus to which it belongs, the second 
