University of Kansas Lawrence 1956 University of Kansas Publications, Museum of Natural History Editors: E. Raymond Hall, Chairman, A. Byron Leonard, Robert W. Wilson Volume 8, No. 9, pp. 499-533 Published June 12, 1956 University of Kansas Lawrence, Kansas PRINTED BY FERD VOILAND, JR., STATE PRINTER TOPEKA, KANSAS 1956...

The eastern woodrat exerts important effects on its community associates by its use of the vegetation for food, by providing shelter in its stick houses for many other small animals, and by providing a food supply for certain flesh-eaters. In the course of our observations on this rodent on the University of Kansas Natural History Reservation, extending over an eight-year period, from February, 1948, to February, 1956, these effects have changed greatly as the population of woodrats has constant

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 characterize

(A) Map of part of University of Kansas Natural History Reservation, showing first-capture sites for all woodrats live-trapped in the autumn of 1948. Because of the short time involved and the few traps available, much of the area shown was not thoroughly trapped. Woodrats were abundant, though much less so than in 1947, as shown by the large number of deserted houses. (B) Map of woodrat study area, same as shown in (A), showing first-capture sites for all woodrats live-trapped in 1949. Woodrats

Some 56 species of animals that regularly prey on small vertebrates live on the Reservation. Many of the larger kinds may take woodrats occasionally. Because of size, habitat preferences and the time and manner of hunting, five species stand out as the more formidable enemies—the horned owl ( Bubo virginianus ), prairie spotted skunk ( Spilogale putorius ), long-tailed weasel ( Mustela frenata ), pilot black snake ( Elaphe obsoleta ) and timber rattlesnake ( Crotalus horridus ). Throughout the s

Rainey (1956) listed many kinds of small animals that use the houses of the eastern woodrat and live in more or less commensal relationships with these rodents. A situation unusually favorable for observing woodrats and their associates was discovered on the Reservation where, in July, 1948, two old strips of sheet metal, each covering an area of approximately 25 square feet, were used as shelter by a lactating female with three young. This was on a brushy slope just below an old quarry site. A

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

Rainey (1956) has listed 31 food plants that are used by the woodrat in northeastern Kansas. He has emphasized that each rat usually obtains its food from plants growing in the immediate vicinity of its house, and that individuals thus differ greatly in their feeding, according to the local vegetation. Therefore, with a sufficiently large number of observations, the list of food plants might be greatly expanded, to include most of the local flora, with the exception of the relatively few kinds t

Reproductive activity continues to some extent throughout the year except in late autumn and early winter. Presence of a vaginal orifice was used as an indication of sexual activity. In most instances the orifice was not indicative of actual oestrus, as it persisted through the preceding and following stages of an oestrus cycle. In anoestrus the orifice is sealed, the genitalia are reduced in size and the skin in the genital region is white. Immature females, and adults during most of the winter

At birth woodrats weigh approximately 10 grams or a little more. In a litter born in captivity and kept by Rainey, the average gain amounted to a little more than 1.5 grams per day during the first two months, but in the third month it was somewhat less. As this was an unusually large litter, of five young, one more than the female's teats could accommodate, their growth may have been a little less rapid than in most of those under natural conditions. At an age of three months they averaged appr

The longest span of records for an individual woodrat recorded was 991 days in a female, already adult when she was first caught on November 18, 1948. Other relatively long spans of records were: 827 days in a male, adult when first caught on March 16, 1952; 754 days in a female, also adult when first captured; 649 days in a male first captured as a juvenile; 465 days in a male, adult when first captured; 409 days in a male, juvenile when first captured; 399 days in a female, juvenile when first

Plant succession resulting from land use practices created habitat conditions especially favorable for woodrats in the late nineteen forties in northeastern Kansas, and particularly on the University of Kansas Natural History Reservation. With protection from prairie fires, woody vegetation had encroached onto areas that were formerly grassland, and, later, fencing against livestock permitted dense thickets of undergrowth to develop. In this region the woodrat usually lives in a forest habitat,