Life History of the Kangaroo Rat | Page 8

has fallen completely, and unless the moon is shining the
animal can hardly be seen. Were it not for the white tail-brush of
spectabilis and its white belly when upright on the hind legs and tail,
one could not as a rule see the animal at all when it makes its first
evening appearance. With the first streak of dawn activity usually
ceases completely and much more abruptly than it began with the
coming of darkness, but on a recent occasion Vorhies observed that a
kangaroo rat which did not appear until near morning remained above
ground until quite light, but not fully daylight. On removal of the plug
from the mouth of a kangaroo rat burrow, one may sometimes see a

fresh mass of earth and refuse shoved into the opening from within. As
often as not, however, even this unwelcome attention does not elicit
any response by day, the great majority of the burrow openings of this
species, as observed by the authors, remaining permanently open.
The ordinary activities of the kangaroo rat in southern Arizona can
scarcely be said to show any true seasonal variation. The animals are
active all the year in this region, there being neither hibernation nor
estivation, both perhaps being rendered unnecessary by the storage
habit, to be discussed in full later (pp. 15-16), and by the mildness of
the winter climate. On any particular night that the weather is rainy, or
the ground too wet and cold, activity is confined to the interior of the
burrow system, and for this reason one has no opportunity to see a
perfect imprint of the foot in freshly wet soil or in snow. On two or
three of the comparatively rare occasions on which there was a light
fall of snow on the Range Reserve a search was made for tracks in the
snow. At these times, however, as on rainy nights, the only signs of
activity were the pushing or throwing out of fresh earth and food refuse
from within the burrow. This is so common a sight as to be complete
evidence that the animals are active within their dens during stormy
weather but do not venture outside. Trapping has again and again
proved to be useless on rainy nights, unless the rain is scant and a part
of the night favorable, in which case occasional individuals are taken.
These statements apply to the Range Reserve particularly; the facts
may be quite different where the animals experience more winter, as at
Albuquerque, N. Mex., although in November, 1921, Vorhies noted no
indications of lessened activity in that region.
PUGNACITY AND SOCIABILITY.
So far as their reactions toward man are concerned, kangaroo rats are
gentle and make confiding and interesting pets; this is especially the
case with merriami. This characteristic is the more surprising in view
of the fact that they will fight each other so readily and so viciously,
and yet probably it is explained in part by their method of fighting.
They do not appear to use their teeth toward each other, but fight by
leaping in the air and striking with the powerful hind feet, reminding

one most forcibly of a pair of game cocks, facing each other and
guarding in the same manner. Sometimes they carry on a sparring
match with their fore feet. Biting, if done at all, is only a secondary
means of combat. When taken in hand, even for the first time, they will
use their teeth only in the event that they are wounded. The jaws are not
powerful, and though the animals may lay hold of a bare finger, with
the apparent intention of biting, usually they do not succeed in drawing
blood. As Bailey says (1905, 148), they are gentle and timid, and, like
rabbits, depend upon flight and their burrows for protection.
The well-traveled trails elsewhere described (p. 10) indicate a degree of
sociability difficult to explain in connection with their pugnacity
toward each other. While three or four individuals may sometimes be
trapped at a single mound, more than two are seldom so caught, and
most often only one in one night. Trapping on successive nights at one
mound often yields the larger number, yet in some cases the number is
explained by the fact that two or three nearly mature young are taken,
and the capture of several individuals at a single mound can not be
taken to indicate that all are from the one den. Our investigations tend
strongly to the conclusion that only one adult occupies a mound, except
during the period when the young are in the parental (or maternal) den.
In the gassing and excavating of 25 or more mounds we have never
found more than one animal in a den, except in one instance, and then
the two