heir droppings. In the spring
of 1949 the bin and rock crusher were removed, but at least one rat
continued to live in the rock wall. In the summer of 1951 several tons
of corn ruined in the flood were dumped on the top of the bank above the
wall. By autumn, Norway rats, either brought in with the corn or
attracted by it, had taken possession of the wall, evidently displacing
the woodrats, which were no longer present. Although this Old World
murid rat is much different from the woodrat in habits, it seemingly can
compete with it and replace it where habitat conditions are otherwise
favorable for both.

_Movements_

The woodrat is dependent on the stick houses that it constructs for
shelter. For each individual the house constitutes a home base to which
it is attached, and about which its movements revolve. The area within
which routine daily movements are confined constitutes the home range,
which is variable in size and shape. An individual may, and usually
does, alter its home range over periods of time. The home range is
somewhat nebulous because the rat may at any time move far beyond the
small area to which its activities are largely confined. It may be
motivated by sexual urge or other voluntary wandering; it may be
enticed by a food supply or some other specific attraction not available
near its house; or it may be forcibly displaced by an intruder or may
abandon in favor of an offspring.

An occupied house normally has several runways radiating from it. These
are well worn paths, smoothed by use, and cleared of obstructions, and
the rat tends to keep to them in its foraging expeditions. Usually a
trail leads to a bush or tree showing evidence of heavy use by the rat.
Ordinarily such a trail cannot be traced more than 30 feet from the
house, and it seems that the most concentrated foraging occurs within
this short radius. Experience in live-trapping has indicated that the
distance covered by a woodrat in its normal foraging for food is
ordinarily less than 75 feet in any direction from the house.

Usually the rats can be caught in traps only at their houses or nearby
places that they frequent, as indicated by their sign. When travelling,
woodrats make use of overhead cover as much as possible. Storing of food
seems to be associated with the animal's reluctance to wander far from
home. When a rat is gathering preferred food for storage the home range
may be enlarged (or the animal may travel beyond the limi