ces where they were partly or
wholly protected from moisture and sunshine were much less subject to
decay than those in more open situations, and remained long after the
rats themselves were gone. Accumulations of droppings in depressions in
rock surfaces beneath overhanging ledges likewise have lasted for many
years. The rock outcrop provided a continuous travelway along the
hilltops, and even parts that were not permanently occupied usually had
some sign. The following types of situations were found to be especially
favorable for occupancy: deep crevices beneath overhanging projections
of the ledge; large flat boulders broken away from the main ledge; thick
clumps of brush (usually fragrant sumac, _Rhus trilobata_) providing
shelter and support for the house; logs fallen across the ledge
providing support and protection for the house structure.

A second outcropping limestone stratum approximately 20 feet below the
level of the hilltop was just as extensive as the upper outcrop, but it
was little used by the rats because the exposed rock surface was more
regular, lacking the jagged cracks and deep fissures of the hilltop
outcrop; and it lacked the overhanging projections which provided
overhead shelter for the rats along the upper outcrop. More than ninety
per cent of the rats that were recorded as associated with the outcrops
were at the hilltop stratum.

Second in preference to the hilltop outcrop as a house site was the base
of an osage orange tree in thick woods. This tree occurs throughout the
woodland of the Reservation, having become established when the leaf
canopy was more open, and the whole area was subject to grazing, with
less development of the understory vegetation in the woodland. Houses
were most often situated in those osage orange trees that had been cut
one or more times, and had regenerated with spreading growth form, the
multiple branching stems offering substantial support. Occasionally
houses were built in crotches from two to six feet above ground.

Blackberry thickets also are favorable locations for houses. These
thickets grew up mostly in fenced areas from which livestock were
excluded, but where there was not dense shade--hilltop edges and level
or gently sloping ground adjacent to creek banks. The houses were
usually in densest parts of the thickets where they were almost
inaccessible. Mats of dead canes more or less horizontal, with the live
canes growing up through them, provided effe