The burrow system, or den, in which _spectabilis_ stores its caches of
food materials, has its nest, and remains throughout the hours of
daylight is a complicated labyrinth of tunnels. Ejection of refuse and
soil from this retreat builds up the mound frequently referred to. These
mounds are, as Bailey says, characteristic of the species, and are as
unmistakable as muskrat houses or beaver dams, and as carefully planned
and built for as definite a purpose--home and shelter. They are,
furthermore, the most notable of all kangaroo rat dwelling places
(Nelson, 1918, 400). They range in height from 6 inches to approximately
4 feet and from 5 to 15 feet in diameter.

The mound is built up not only through the cleaning out of chaff and
other food refuse, but through extension and modification of the
tunnels; old tunnels, entrances, and caches of musty food material are
from time to time closed up and others excavated, repair and rebuilding
being especially necessary after the collapse of portions of the den as
a result of heavy rains or trampling by cattle. Ejected material is most
commonly simply thrown out fan-wise from the openings, without much
apparent effort to add to the height of the mound.

There are usually from 6 to 12 entrance holes in each mound opening into
the subterranean burrow system, each hole from 4 to 5-1/2 inches in
diameter. These holes are nearly all situated a little above the surface
of the surrounding soil, and as Price has suggested (in Allen, 1895,
213), this is doubtless a wise provision against flooding, as torrential
rains sometimes occur in the kangaroo rat country.

Both Bailey and Nelson state that as a rule several of the holes are
closed with sand or miscellaneous earth and old storage material during
the daytime, but our observations on the Range Reserve are that such