The Amphibians and Reptiles of Sinaloa, Mexico - Smithsonian ...

AMPHIBIANS AND REPTUJES OF SINALOA, MEXICO 49
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MEAN MONTHLY TEMPERATURE {' C.)
FIG. 5. Temperature-moisture climograph comparing the three lowland localities
in northern (Ahome), central (Guamuchil), and southern (Mazatlan)
Sinaloa, Mexico. Each point represents a month, proceeding counter-clockwise
from January (J).
sites in the lowlands. Precipitation is restricted mainly to the
months of July, August, and September. All localities except Guamuchil
exhibit a secondary peak o£ precipitation in December.
Vegetative growth is dependent on heavy summer rains. The second
author has traveled the length of the state in December and
found the vegetation generally inactive and leafless, except along
the rivers or in areas where the water table is unusually high, as in
the extreme southwest near Teacapan. In making the same trip in
July, he found the vegetation in a progressively advanced stage of
leaf and general activity the further south he traveled.
The percentage of annual precipitation that falls in July, August,
and September, also increases gradually from north to south. The
small amount of precipitation that falls from November through
June results in a very dry period during the first six months of the
year, especially in the northern lowlands (Shreve, 1944:108-09). It