INFLUENCE OF DIET ON DETECTION OF FECAL BILE-ACIDS BY THIN-LAYER CHROMATOGRAPHY

Use of scat analysis to determine food habits of carnivores is depende nt on accurate species identification of scat. Thin-layer chromatograp hy (TLC) of fecal bile acids has been used to identify carnivore scat but relies on an untested assumption that diet does not affect the pro file (incidence and concentration) of fecal bile acids in ways that ob scure species-specific patterns. We conducted a feeding experiment to evaluate the effect of diet on the reliability of TLC as a means of un iquely identifying coyote (Canis latrans) scats. We detected deoxychol ic and chenodeoxycholic acids in all scats from coyotes fed a control diet composed of commercial feed. We detected the same bile acids in o nly 60 (P = 0.012) and 55% (P = 0.005), respectively, of scats from co yotes fed a diet consisting solely of apples. The apple diet also resu lted in fewer (P = 0.001) unidentified steroids than in the commercial diet (3.5/scat, SD = 1.9 vs. 5.6/scat, SD = 1.3) and tended to lower concentrations of fecal bile acids relative to the commercial diet. Un til the effect of diet on fecal bile acid profiles is known, TLC may n ot aid in distinguishing scats among different species.