oted mouse (_Peromyscus leucopus_), short-tailed shrew (_Blarina
brevicauda_), least shrew (_Cryptotis parva_), American toad (_Bufo
americanus_), Great Plains skink (_Eumeces obsoletus_), pilot black
snake (_Elaphe obsoleta_); and one each of bull snake (_Pituophis
catenifer_), spotted king snake (_Lampropeltis calligaster_), red milk
snake (_L. triangulum_), and timber rattlesnake (_Crotalus horridus_).
The snakes which were potential predators on the rats seemed to be
merely utilizing the shelter in these instances, but they may have been
lying in wait for prey there.

Among mammals, the cottontail and the white-footed mouse are the most
persistent users of the woodrat houses, especially those that are no
longer occupied by the rats. On one occasion five white-footed mice were
caught simultaneously in a trap set beside a house at the base of an
osage orange tree. Subsequent trapping showed that this house was no
longer occupied by a rat, but that the mice lived in it. Occupancy of
such an old woodrat house by white-footed mice may continue long after
abandonment of the house by the rat, even after the house has partly
decayed and settled to a small part of its original volume.

Cottontails often have their forms under the edges of houses, either
occupied or deserted. These situations offer protection overhead and on
three sides. Abandoned houses having one or more of the entrance holes
enlarged, as by predators breaking through the side of the house to gain
access to the nest, are especially well adapted for occupancy by the
cottontail. The rabbit may make its form inside the house structure.

The opossum, also, finds the type of shelter that it requires in
abandoned houses that have had the entrances sufficiently enlarged. On
various occasions opossums or their remains have been found in such old
houses, and opossums released from live-traps have been known to seek
shelter in abandoned woodrat houses.

At the old quarry on the Reservation woodrat sign was especially
abundant. A wooden bin approximately seven feet square, used to store
crushed rock before quarrying operations were abandoned, was inhabited
by one rat. At the base of a rock crusher on the top of a bank a few
yards from the bin was an accumulation of sticks and other debris
brought by woodrats. A rock wall at the top of the bank between the
crusher and the bin had many crevices providing shelter for the rats,
and projecting rocks were littered with t