12 PACIFIC COAST AVIFAUNA No. 11 
Major Major 
Zones Faunal Divisions Subfaunal Divisions 
Humboldt Bay 
i Northern Humid Coast 
Marin 
| HuMip Coast 
BogeAL Santa Cruz 
ORE < 
Trinity 
Sierra Nevadan 
San Bernardino Mountain 
[som 
Sierra Foothill 
Clear Lake 
Sacramento Valley 
CALIFORNIAN San Joaquin Valley 
San Francisco Bay 
San Diegan 
Santa Barbara Island 
AUSTRAL 
Modoc 
Great BASIN Inyo 
(or Artp INTERIOR) Mohave Desert 
Colorado Desert 
Reference to plate III will show that, as with zones, the outlines of the 
faunal areas in California are very irregular. The limit of subdivision of faunas 
is not as sharply determined as with zones, and there is here more latitude for 
the personal element. The boundaries as given are, of course, merely approx- 
imate, and the areas themselves will doubtless receive extensive modification on 
the basis of future, more intensive, geographical study. - Still, their recognition 
as now defined has proven of great use in the attempt to formulate briefly the 
extent of the ranges of the many species of birds involved. 
A third order of distributional behavior, wholly complementary to the other 
two, has been employed elsewhere in the study of the distribution of California 
birds,—that by associations (see Grinnell, Univ. Calif. Publ. Zool., x11, 1914, pp. 
64, 66, 90). Since this manner of occurrence is mostly local in its application, 
and since its demonstration with regard to our birds would add very largely to 
the bulk of the present paper, it has been left almost altogether out of consider- 
ation in this connection. The present paper is thus given over to the treatment 
of species upon the more purely geographical schemes, those of life zones and 
faunal areas. The fact that birds, in spite of their superior powers of locomo- 
tion, are often confined within very narrow ranges of climatic conditions, tends 
to develop lively interest in this field of ornithological study. 
Detailed, critical, and statistical marshalling of the facts of distribution of 
our many species of birds, through the preparation of annotated tables, fauna by 
fauna, zone by zone, and association by association, is a piece of work greatly 
to be desired. Whoever undertakes it, however, will doubtless find his results 
more significant if birds be handled along with other vertebrate classes. In the 
meantime, accumulation of a very great deal more of distributional detail is to 
be hoped for, as regards not only birds, but the other vertebrate groups as well. 
