Characteristics and adaptive significance of latrines of swamp rabbits (Sylvilagus aquaticus)

Abstract

Three different types of forests (mature, mixed upland, and cut-over) in central Arkansas were surveyed in June and October 1991 and February and May 1992 for latrines of swamp rabbits (Sylvilagus aquaticus). Swamp rabbits deposited >91% of their fecal pellets on logs. A greater density of pellets were found in February 1992 compared to other months. Length, height, diameter, decay class, and percent cover of moss on logs used as latrines by swamp rabbits were recorded. Logistic regression was used to predict the likelihood that a log would be used as a latrine. Increasing decay class, percentage cover of moss, and diameter of logs were correlated with latrines of swamp rabbits. Height of logs did not distinguish between used and unused logs, but length and season were significant predictors of use of logs as latrines in forests of mature bottomland hardwood and cut-over bottomland. Spatial clumping of latrines and peak use during breeding were consistent with the hypothesis that latrines on logs serve as territorial markers. An alternative hypothesis that swamp rabbits elevated themselves on logs to increase their field of view and coincidentally deposited pellets on logs was tested experimentally with three obstruction treatments; visual + physical, only physical, and a control. Treatments were placed on 1-m sections of 54 logs that had been used as latrines in at least 2 of the 4 monthly surveys. Surveys conducted for 4 months after the installation of obstructions showed a significant interaction between use of a log as a latrine, treatment type, and month of survey.