Factors Affecting Scent Station Visitation Rates of Raccoons and Bobcats

Scent stations are assumed to be a simple and economical method to index furbearer populations, but recent literature challenges the reliability of this technique. We examined several variables that could affect visitation rates of 2 commonly indexed species. Raccoon (Procyon lotor) and bobcat (Felis rufus) visitation rates of scent stations were monitored on the Hatchie National Wildlife Refuge in western Tennessee during summer and fall 1991. Factors tested included placement from water and roads, attractant type, and within-habitat variability of scent-station visitation rates. Placement of scent stations near water (^10 m) increased visitation rates of raccoons. Attractant type (visual vs. olfactory) did not affect visitation rates of bobcats or raccoons regarding visual attraction to a scent station. Differences existed between sites within a habitat for raccoons. Variability did not increase with increasing visitation rates in raccoons and showed only a slight positive slope in bobcats. Reliability of scent station indices may depend on random locations and optimal placements and will require standardization of techniques for each species. Proc. Annu. Conf. Southeast. Assoc. Fish and Wildl. Agencies 48:182-190 1 Present address: Department of Wildlife and Fisheries Sciences, Texas A&M University College Station, TX 77843. 2 Present address: Fish and Wildlife Program, Department of Biology, Montana State University, Bozeman, MT 59717. 3 Present address: Department of Biological Sciences, P.O. Box 5218, University of North Texas, Denton, TX 76203. 4 Present address: Department of Biology, University of Mississippi, University, MS 38677. 1994 Proc. Annu. Conf. SEAFWA Scent Station Visitation 183 Growing interest in furbearer management has intensified the need to determine population changes (Clark and Andrews 1982, Johnson 1982). Various techniques have been proposed, including spotlight counts (Fountain 1976, Andrews 1979, Rybarczyk et al. 1981), track indices (Becker 1991, Stanley and Bart 1991, Van Sickle and Lindzey 1991), and scent stations. The scent station technique was originally developed for foxes (Richards and Hine 1953, Wood 1959), and was later used to monitor populations of other mammalian predators (Conner et al. 1983). Roughton and Sweeny (1982) described scent stations as a practical means to determine trends in carnivore populations. Use of scent stations has increased recently, but questions concerning reliability and repeatability of this index remain (Conner et al. 1983). Recent research has focused on modifying techniques to standardize this method (Conner et al. 1983). Ideally, scent station indices should correlate with population densities. Few studies have correlated scent station indices with population densities (Davison 1981, Conner et al. 1983, Diefenbach et al. 1994), and results from these studies have varied. Attempts to standardize techniques had led to the search for higher visitation rates (Morrison et al. 1982, Roughton and Sweeny 1982), assuming a correlation of visitation rates and accuracy of a density estimate exist (Hatcher and Shaw 1981, Roughton and Sweeny 1982). Low visitation generally results from low mammalian predator densities, large home ranges, and/or territoriality (Becker 1991). Variation in visitation rates occur among seasons, habitats, odor attractants, and construction materials (Sumner and Hill 1980, Morrison et al. 1982, Conner et al. 1983, Linscombe et al. 1983, Turkowski et al. 1983, Leberg and Kennedy 1987, Strapper et al. 1989). Preferences for habitat, odor attractant, and construction materials by a species are uniquely influenced by behavior. Because species-related differences occur (Morrison et al. 1982, Conner et al. 1983), standardizing techniques to the behavioral characteristics of each species is essential. Standardizing techniques should reduce within-sample variances and accentuate between-sample variability, thereby allowing for equitable comparisons within a region for a given species. Previous investigations have focused on attractant and substrate used at the scent station (Morrison et al. 1982). Technique improvements have concentrated primarily on coyotes (Canis latrans). Because coyotes use unimproved roads as travel lanes (Hodges 1975, Morrison et al. 1982, Roughton and Sweeny 1982), and cost-effectiveness is increased by setting scent stations along roads, most research has centered on increasing visitation rates for all furbearer species at road sites, while minimizing multiple visits by an individual animal (Roughton and Sweeny 1982, Linscombe et al. 1983, Diefenbach et al. 1994). Sumner and Hill (1980) and Leberg and Kennedy (1987) described placing scent stations for raccoons near water to increase precision, but there were no data to corroborate this assumption. Because many carnivores do not use roads as corridors, placement of scent stations may differentially affect visitation rates among these species. 1994 Proc. Annu. Conf. SEAFWA