Reactions to Odor Trails in Bullsnakes

Abstract

specifics on the basis of scent trails (Gehlbach et al., 1971; Parker and Brown, 1980; Ford, 1982; Brown and MacLean, 1983; Ford and Schofield, 1984; Chiszar et al., 1986; Ford and O'Bleness, 1986; Burger, 1989). In many instances, snakes were able to distinguish conspecific scent trails from congeneric trails (Brown and MacLean, 1983; Ford and Schofield, 1984; Ford and O'Bleness, 1986; Burger, 1989; Burger et al. 1991). These scent trails have been speculated to facilitate hibernaculum formation or location (Heller and Halpern, 1981; Brown and MacLean, 1983; Ford, 1986; Burger, 1989, 1990; Burger et al., 1991), mate location (Ford and O'Bleness, 1986), or species recognition (Ford and Schofield, 1984; Ford, 1986; Ford and O'Bleness, 1986). In addition, snakes respond to predator odors (Burger, 1989, 1990), and prey scent trails (Gehlbach et al., 1971; Chiszar et al., 1986; Fritts et al., 1989). The majority of studies involving the reaction of snakes to odors have been done in the laboratory (e.g., Parker and Brown, 1980; Burger, 1989); only a few studies have been performed in the field (e.g., Parker and Brown, 1980). In this study, we set out to investigate odor detection by bullsnakes (Pituophis melanoleucus sayi) in a field situation. Bullsnakes both scenttrail conspecifics (Parker and Brown, 1980; Burger, 1989), and react to predator odors (king snakes, Lampropeltis getulus; Burger, 1989; Burger et al., 1991). This study was performed at Smith Lake on the Crescent Lake National Wildlife Refuge in the sandhills of Garden County in western Nebraska. The area surrounding Smith Lake is typical sandhill prairie habitat consisting primarily of grasses and yucca (see Imler, 1945; Weaver, 1965; Gunderson, 1973, for detailed site descriptions). Portions of the area around Smith Lake were grazed by cattle during the study period. A 4.1 km drift fence (see Fitch, 1951) along the west side of Smith Lake was erected in 1987 and 3.3 km of fence was added on the east side in 1988. The drift