Fig. 2. Maps showing home ranges of cottontails in relation to woodland and open fields on the study area. One inch equals approximately 470 feet. Each home range is shown slightly rounded from the polygonal figures obtained by connecting actual points where the animal was recorded. Upper Left. An area of 4.6 acres occupied by a cottontail in winter, increased to 6.5 acres in summer by the animal crossing a narrow grassland strip to another woodland edge. Lower Left. Showing increasing size of home range of a female cottontail; in July, 1954 (at age of three weeks), she had a range of .25 acre; September, 1954, 1.5 acres; December, 1954, 8 acres; and December, 1955, 11 acres. Right Half. Two home ranges of a cottontail which moved from its original area to occupy a new one 410 feet farther north across a field in September and October, 1955.
Cottontails range over a larger area in summer than they do in winter because suitable cover and food is more abundant in summer. One cottontail (Figure 2, upper left) lived in a woodland home range of 4.6 acres in the winter but increased the range to 6.5 acres in summer by crossing the narrow overgrown end of a field to another woodland area. Another cottontail (Figure 3, top part) lived in a woodland home range of 7.9 acres in winter but in summer increased the home range to 9.5 acres by including also a part of an adjacent field. Other cottontails increased their home ranges in summer by five to 15 per cent.
On the average, male cottontails had a larger (by 13 per cent) home range than females probably because of the increased activity of males in the breeding season and the decreased activity of females when pregnant and caring for young. Nevertheless, some of the largest home ranges measured were those of females.
Fig 3. Diagrams showing home ranges of cottontails in relation to woodland and open fields on the study area. One inch equals approximately 545 feet. Each home range is shown slightly rounded from the polygonal figures obtained by connecting actual points where the animal was recorded. Upper. Winter range of 7.9 acres (solid line) increased to 9.5 acres in summer by area in dashed line. Lower. Overlapping home ranges of four of the many cottontails living on the study area. Each of the four cottontails occupied approximately the same home range throughout the year.
The size of the home range in immature cottontails varies between 0.1 acre and 4.0 acres, depending on the age and size of the individual. Fourteen young cottontails between three and six weeks of age did not leave areas of approximately one acre in each instance. Nine cottontails between six weeks and 18 weeks of age lived in areas of about two acres. By the time cottontails are four to five months old they inhabit a home range of four to eight acres.
One cottontail (Figure 2, lower left) born in July, 1954, was estimated to have wandered over approximately 0.25 acre at an age of three weeks. In September this cottontail occupied a home range of one and one-half acres. By December it was five months old and occupied an area of about eight acres. In the next year it enlarged its home range to 11.5 acres.
The cottontail usually settles down in one area and stays there until it dies. Changes from one home range to another are unusual, but minor shifts, in response to changes in vegetation and weather, are common. In one exceptional instance (Figure 2, right) a male cottontail, occupying a home range of 11.2 acres in a woodland, suddenly shifted to a new area that barely overlapped its former home range at one edge. Two months after the change was first noticed the cottontail was living in a new home range of 6.6 acres 300 feet from its original home range. In changing from one home range to the other the cottontail traveled along a dry stream bed and was captured there three times.
Maps of the home ranges of four of those 18 cottontails for which sufficient data were collected to determine the size of home range are shown in the lower part of Figure 3.