Many studies have related estimates of predator diet to prey detectability in scats, but no studies have examined effects of diet on deterioration of scat in the field and the ability to recognize the species depositing the scat. Scats from captive bobcats (Lynx rufus) fed 1 of 3 diets—(mice [Mus musculus] and rats [Rattus norvegicus], rabbit [Oryctolagus cuniculus], and deer [Odocoileus virginianus])—were used to determine the effect of prey species on the integrity of an exposed scat. Diet affected (P<0.001) mass loss of scats. Mass loss of scats containing mice and rats was similar (P>0.05) to mass loss of scats containing rabbit, but mass loss of scats containing deer was greater (P<0.05) than scat containing mice and rats or rabbit. If mass loss of scat reduces the ability of biologists to identify the species depositing the scat, those scats that lose mass at a faster rate would become unidentifiable sooner. These scats would then not be collected or would not be included in predator-specific diet analyses, which could bias the results (e.g., underrepresent the importance of deer in bobcat diet). We suggest that diet-specific mass loss of scats may occur in other species and that research is needed to evaluate this possibility. Studies also are needed to determine adequate sampling intervals to eliminate effects of mass loss bias.