Laboratory efficacy study of six concentrations of warfarin bait for black-tailed prairie dogs

Six different concentrations of warfarin bait (0.0, 44.7, 89.5, 233.0, 407.0, and 777.6 ppm) were fed for 15 days to black-tailed prairie dogs to determine efficacy. The resulting mortality was 0, 30, 50, 60, 100, and 80%, respectively. No difference in mortality was observed among the sexes. Differences in bait consumption were greater between the control group and all treatment groups than among the treatment groups (HSD=0.430, P<0.05). Warfarin consumption was highly correlated (r=0.916) with the concentration of warfarin present in the baits. The resulting LC50 and LC90 were 97 and 831 mgkg−1, respectively. Mean body weights of prairie dogs across treatments were similar (F=0.657, P=0.658) as were the variances (L=0.545, P=0.741) at test initiation (day 0). At test termination, weight loss was greater in the treatment groups than in the control group (P=0.001), but no difference was evident among the treatment groups (HSD=1.000, P<0.05). Body weight loss increased as the treatment group dosage increased. The control group was the only group in which body weight increased throughout the test.