was begun in September, 1948, and was pursued most
intensively in the autumn of 1948 and in 1949, with relatively small
amounts of data obtained in 1950 and 1951 because of the great reduction
in numbers of rats. Rainey's field work began in the spring of 1951 and
was continued through 1954, concentrating on a colony in the extreme
northwestern corner of the Reservation and on adjacent privately owned
land. In actual numbers of rats live-trapped and for total number of
records the two sets of data are comparable. Fitch's field work
consisted chiefly of live-trapping while Rainey's relied also upon
various other approaches to the woodrat's ecology. Rainey's findings
were incorporated originally in a more comprehensive report (1956), from
which short passages have been extracted that are most pertinent to the
present discussion. Our combined data represent 258 woodrats (153
Fitch's and 105 Rainey's) caught a total of 1110 times (660 Rainey's and
450 Fitch's). Rainey's records pertain, in part, to woodrats outside the
Reservation but within a few hundred yards, at most, of its boundaries.

_Habitat_

In the autumn of 1948 the population of woodrats was far below the level
it had attained in 1947 or earlier, but the rats were still abundant and
distributed throughout a variety of habitats. Almost every part of the
woodland was occupied by at least a sparse population. Also, many rats
lived beyond the limits of the woodland proper, in such places as
deserted buildings, thickets, roadside hedges, and tangles of exposed
tree roots along cut banks of gullies. All these situations are
characterized by providing abundant cover, a limiting factor for this
woodrat.

In 1947, when the population of woodrats was especially high, plant
succession on the wooded parts of the Reservation may have been near the
optimum stage for the rats. For some 80 years, since the time the land
was first settled and prairie fires were brought under control, woody
vegetation has been encroaching into areas that were formerly grassland.

About 1934 the University changed its policy with regard to treatment of
the tract that was later made the Reservation. Up to that time, most of
the area had been used as pasture and subjected to heavy grazing, but
several fields had been fenced and cultivated. Under the new policy the
hillsides and hilltop edges with open stands of various deciduous trees
were enclosed with stock fences and protected from grazing.