1925 J Storer: A Synopsis of the Amphibia of California 
3 
been made to indicate the times and places where California am- 
phibians may be sought so that investigators desiring to use these 
species for experimental purposes may hunt for them with expectation 
of success. It has also been hoped that, stimulated by the data here 
presented, other students may be attracted to the field and the life- 
histories of the California amphibians investigated in greater detail. 
The climate of California, particularly of the interior valley and 
foothill districts, involves conditions widely different from those in 
eastern North America and western Europe. Here a rainy season of 
limited duration and characterized by moderate temperatures during 
the 'winter’ months is followed by a long summer season of high 
daily (though moderate nightly) temperatures, with few or no summer 
rains and with low diurnal relative humidity. 
This peculiar type of climate exercises a profound effect on the 
seasonal behavior of many different forms of life. Among mammals 
it has been found that the California Ground Squirrel aestivates 
during the latter part of the dry period, tiding over the season when 
food is scant in a resting or dormant condition analogous to that of 
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arctic animals which hibernate when. their food supply disappears or 
lies buried under snow. Many of the species of birds which nest in 
the territory ydiere the semi-arid type of climate prevails react to 
the extreme dry season of the ‘ summer ’ months by migrating to more 
favorable locations. Among the so-called 'permanently resident’ 
species of birds in the California foothills there are a number, such as 
the Spurred Towhee, Wren-tit, Bush-tit, and Vigors Wren, which each 
summer perform an altitudinal migration, moving in late summer up 
into the higher zones of the mountains where they continue until the 
rains break and induce a renewal of the food supply at the lower 
levels. Among the native insects some forms await the arrival of the 
rainy season for their breeding activities, thus assuring a sufficiency 
of moisture for the more susceptible egg and early larval stages. Of 
plants which are native to the 'semi-desert’ conditions of interior 
California, many genera exhibit structural features, such as sclero- 
phyllous stems and reduced leaf surface, which are of direct service 
in meeting a condition of limited water supply, while many species 
advance the seasonal program so that growth and blossoming is accom- 
plished before the advent of the dry weather. 
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