pions
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.

NATURAL CHECKS.

The enemies of the kangaroo rat are not determined in detail, or as to
relative importance, but the badger (_Taxidea taxus berlandieri_) and
the kit fox, or swift (_Vulpes macrotis neomexicana_), may well be
foremost. Dens which have been deeply excavated by badgers are
frequently seen, and sometimes two or three badger tunnels penetrate one
burrow system. Dens thus despoiled are probably soon reoccupied even if
the original owner is captured, and in the course of a few months the
reworking of the abode obliterates the signs of destruction.

Droppings of the kit fox show an abundance of bones of small mammals of
kangaroo rat size, among them those of _spectabilis_.

Bobcats (_Lynx baileyi_) and coyotes (_Canis mearnsi_) probably are a
prejudicial factor. Skunks may sometimes be able to surprise the
kangaroo rats, but probably not often. The western horned owl (_Bubo
virginianus pallescens_), the barn owl (_Tyto alba pratincola_), and
perhaps others may well be among the most feared enemies, but no special
investigation of owl pellets on the reserve has been possible. In 592
barn-owl pellets from California were found remains of 230 kangaroo
rats, only one other rodent being represented by a