74 
THE CONDOR 
Voi,. XI 
“Biological Survey of the San Francisco Moun- 
tain Region, Arizona,” and is concerned in part 
with the same problems. In the introduction 
the author says: 
“The San Bernardino mountains proper con- 
stitute the largest high mountain group in 
southern California, and include the highest 
peak south of Mt. Whitney. The forested area 
is more extensive than elsewhere in southern 
California, and promised a more abundant 
fauna. Furthermore, the isolation of this 
mountain group from any other of approxi- 
mately similar altitude afforded an attractive 
feature. My interest therefore centered in 
this region, and I carried on investigations, 
with the purpose of ascertaining the composi- 
tion of its fauna, and the local distribution of 
the component species. ” 
The scope of the report is fairly indicated by 
the table of contents which is as follows: (1) 
Introduction; Itinerary. (2) Life Zones of the 
Region, with lists of the plants belonging to 
each. (3) General Considerations: A discus- 
sion relating to bird population and the in- 
fluences modifying it. (4) Some plants of the 
Region: A list of important species with notes 
on their distribution. (5) The Birds: A list 
of 139 species found in the region with a de- 
tailed record of distribution in each case, ex- 
tended biographical accounts of many species, 
and critical notes on others. (6) The Mam- 
mals: A list of 35 species detected in the re- 
gion with statements of distribution, habits and 
measurements of specimens. (7) The Rep- 
tiles: A list of 20 species observed, with 
notes on food, habits and range. 
Four life zones are included in this region. 
The Lower Sonoran zone occupies the Mojave 
desert plateau to the north, and parts of the 
much lower San Bernardino valley and San 
Gorgonio pass to the south. The Lfpper So- 
noran embraces the vast chaparral belt of the 
Pacific slope, as well as the pinyon belt of the 
desert slope. Next above comes the Transi- 
tion which comprises the major part of the 
considerable forested area, predominating 
above the 6500-foot contour. Finally, the 
Boreal occupies the highest parts of the region, 
largely above the 9000-foot contour. A colored 
map and profile of the mountains give an ex- 
cellent idea of the distribution of these life 
areas. 
The divisions of the Boreal into Canadian, 
Hudsonian and Alpine-Arctic were difficult to 
distinguish, and no great wonder for only 
three trees occur — Finns murrayana, P. flex- 
ilis and Populus tremuloides. Boreal islands 
of small area are usually difficult to subdivide 
in proportion as they are distant from some 
Boreal feeder of considerable extent, although 
of course aridity and unfavorable soil play a 
very important part in reducing boreal spe- 
cies. The paucity of species in the present 
instance is emphasized if comparison is made 
with the central Sierra Nevada, where the 
Canadian has in favorable localities 8 or 9 
trees (4 or 5 characteristic) and the Hudsonian 
5 or 6 (2 at least confined to that belt). If a 
count of the shrubs were taken the poverty of 
the San Bernardino Mountain flora would be 
even more evident. In the Sierra Nevada the 
shrubby plants are more valuable, sometimes, 
than trees for tracing zone boundaries in de- 
tail. In the San Bernardino mountains an 
upper and lower division of the Transition 
seemed to be more easily distinguishable than 
the Canadian from Hudsonian, or the latter 
from Alpine-Arctic. 
LTnder “General Considerations” the author 
describes some of the influences which modify 
bird population. In July, when the season of 
scarcity arrives in the valleys on the advent of 
the summer drought, many birds that have 
raised broods in April, May and June, begin to 
migrate up the mountains, where the season of 
plenty is just beginning. The highlands 
are thus a ready refuge when the Upper and 
Lower Sonoran zones become comparatively 
barren under the July heat. “Without the 
mountains to accommodate the excess of bird 
population, which could not be supported in 
late summer on the withered lowlands, we 
would have far fewer birds in the spring. ” Both 
the residents and early summer visitants of 
the valleys, who have availed themselves of 
the hospitality of the mountains, return to 
the lowlands in the fall. The visitants thus 
become transients in the autumn before un- 
dertaking the southeastward migration to 
their winter habitat. 
To the regular summer residents of the 
mountains — those which breed there and 
whose number is about doubled by the acces- 
sion of offspring — are added the hordes of sum- 
mer invaders, with their young, increasing the 
original population of the mountains at least four 
fold. The supply of food seemed bountiful 
enough for an even greater number of birds. 
Since the aggregate population probably re- 
mains constant from year to year, the annual 
increase of about half a million (these figures 
being merely illustrative for the region under 
consideration) must succumb before the next 
nesting season. The determining factor, the 
author believes, is the food supply of the vari- 
ous species in their winter habitat, wherever 
that may be — either the mountains, in the case 
of the few permanent residents, or the lowlands 
in the case of the migratory forms. It is not 
possible in this short notice to advert to several 
illustrative examples, nor indeed to consider 
all the conclusions reached. The chapter is 
interesting and the points well taken. 
Perhaps the rarest find among the birds was 
a specimen of Otus flammeola idahoensis cap- 
tured June 15, 1905, at Bluff Lake. Regulus 
