Arizona \ 
Exp. Sta./ 
LIFE HISTORY OF THE KANGAROO RAT. 
25 
increases in storage appear somewhat after the growth period proper, 
since storing does not get well under way until the seed crop Ls 
mature. The banner-tailed kangaroo rat shows a marked adapt- 
ability to different foods available in the neighborhood of its bur- 
rows. 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 suit- 
able localities clearly indicate that the animal is successful in meet- 
ing the changing and sometimes extremely adverse conditions of its 
environment. 
At times, more especially in the seasons of active growth, some of 
the green and succulent portions of plants are eaten. This was very 
noticeable in the spring of 1919, when a most luxuriant growth of 
Mexican poppy {Eschscholtzia mexicana) occurred. Stomachs at this 
time were filled with the yellow and green mixture undoubtedly pro- 
duced by the grinding up of the buds and flowers of this plant. 
Small caches of about a tablespoonful of these buds were also found 
in the burrows at this time. Occasionally in spring one m&y find a 
few green leaves of various plants, Gaertneria very commonly, 
tucked away in small pockets along the underground tunnels, indi- 
cating that such materials are used to some extent. As has been 
shown in detail, however (Table 1), the chief storage, and undoubt- 
edly the chief food, consists of air-dry seeds. 
The character of the storage, the absence of rain for months at a 
time in some years, and the consequent failure of green succulents 
show that without doubt spectabilis possesses remarkable power, as 
to its water requirements, of existing largely if not wholly upon the 
water derived from air-dry starchy foods, i. e., metabolic water serves 
it in lieu of drink (Nelson, 1918, 400), this being formed in con- 
siderable quantities by oxidation of carbohydrates and fats (Bab- 
cock, 1912, 159, 1T0). During the long dry periods characteristic 
of southern Arizona, no evidence that the animal seeks a supply of 
succulent food, as cactus, is found; and if it may go for two, three, 
or six months without water or succulent food, it is reasonable to 
suppose that it may do so indefinitely. In the laboratory spectabilis 
ordinarily does not drink, but rather shows a dislike for getting its 
nose wet. During the periods of drought the attacks upon the 
cactuses by other rodents of the same region, as Lepus, Sylvilagus, 
Neotoma,, and Ammospermophilus, become increasingly evident. 
The list of plant species thus far found represented in the storage 
materials of spectabilis on the Range Reserve is shown in Table 3. 
