| 1921. | |
| | |
22 | Jan. 1 | 2,333 | Fair.
23[4] | Nov. 7 | 1,685 | Good.
24[4] | Nov. 8 | 5,750 | Do.
| | |
------------+-----------+-----------+-----------

[Footnote 3: Changing from poor summer season of 1918 to excellent
spring growth of 1919.]

[Footnote 4: From near the Sandia Mountains, N. Mex.; others from
United States Range Reserve, near the Santa Rita Mountains, Ariz.]

In presenting Table 2, showing quantity of storage per burrow correlated
with the time of year and the character of the preceding growing season,
the fact may be emphasized that the growing seasons in southern Arizona
are two in number--early spring and midsummer. The spring season is the
less important, the plants consisting chiefly of a variety of small
annuals, while the important range grasses make their chief growth and
head out almost exclusively in the July-August rainy season. It may be
noted also that the actual increases in storage appear somewhat after
the growth period proper, since storing does not get well under way
until the seed crop is mature. The banner-tailed kangaroo rat shows a
marked adaptability to different foods available in the neighborhood of
its burrows. It must, perforce, adapt itself and its storage program to
the food that it can get, and this varies enormously with the climatic
conditions of successive seasons. The large numbers present in suitable
localities clearly indicate that the animal is successful in meeting the
changing and sometimes extremely adverse conditions of its environment.