It is doubtful whether any animals live in a truly commensal
relationship with _spectabilis_, but of not unfriendly associates there
are a great number. It is the experience of Bailey, corroborated by
observations of Vorhies on living animals, that these kangaroo rats are
active in defending their caches of food, and will even fight
individuals of the same species savagely and to the death. One moonlight
night a strange individual was liberated on a mound. It deliberately
entered one of the openings, but after about two minutes' time made an
exceedingly rapid exit, running rapidly out of sight as if pursued,
though the owner of the home did not appear outside of the burrow. There
can be little doubt that the stranger was precipitately ejected by the
owner. We suspect, though this is a point difficult to prove
satisfactorily, that _merriami_ does not always store food supplies for
itself, but visits the burrows of _spectabilis_ regularly to pilfer the
seed stored therein. The observed facts thus far recorded which suggest
this are that in no _merriami_ burrow examined has a store of food been
found, and also that in trapping for _spectabilis_ on its own
characteristic mounds one catches a large percentage of _merriami_.
On two separate occasions Vorhies has observed the smaller species
running over the mounds of the larger, actually carrying away the grain
which had been placed to entice the larger when it might appear. (In
these cases the larger species did not put in an appearance until near
morning.) Furthermore, the dens of _merriami_ are often connected by
distinct runways with those of _spectabilis_, indicating much traveling
or visiting. That this is probably not friendly visiting is suggested by
the certainty with which an individual of the larger species will strike
and kill one of the smaller when they are placed together in the same
inclosure. The word "thief" expresses this suspected relationship better
than would the term "parasite."
It is not to be expected that such obvious shelter retreats as the
mounds of _spectabilis_ should fail to attract the attention of other
animals. We have found a small gecko (_Coleonyx variegatus_), scorpions
of two or three undetermined species, and certain insects (of the Order
Orthoptera) to be very common inhabitants of the dens. With the
exception of the parasitic insects the most common are wingless
locustids (_Ceuthophilus_ spp.) and the peculiar wingless females of a
species of cockroach (_Arenivaga erratica_). These two are seldom absent
when a burrow is excavated, the female cockroaches being abundant,
although the winged males have never been taken in the burrows.
Cary's observations at Monahans, Tex., and those of others at numerous
localities, combined with our own, show that at various times the dens
furnish protection and shelter for various species of cottontail rabbits
(_Sylvilagus_), ground squirrels (_Citellus_ and _Ammospermophilus_),
wood rats (_Neotoma_), grasshopper mice (_Onychomys_), rattlesnakes
(_Crotalus_), and most of the common lizards. Of these the ground
squirrels _Citellus tereticaudus_ and _Ammospermophilus harrisii_ are
most often noted on the Range Reserve using the dens as a retreat, the
_Ammospermophilus_ seldom being observed to enter any other kind of
burrow. It should be added that the total observations include dens
which have been deserted by their rightful owners.