EFFECTS OF INGESTED TUNGSTEN-BISMUTH-TIN SHOT ON CAPTIVE MALLARDS

Steel shot is required for waterfowl hunting in the United States, but hunter dissatisfaction with steel's perceived ballistic performance h as reduced compliance with steel shot laws, contributed to the loss of waterfowl hunters nationwide, and renewed interest in an alternative non-toxic shot with ballistic qualities similar to lead shot. We evalu ated the acute toxicity of an alternative shot by orally dosing 20 8-w eek-old game farm mallards (Anas platyrhynchos) with 12-17 pellets (xB AR = 1.03 g) composed of tungsten, bismuth, and tin (TBT). Ducks were monitored for 32 days for evidence of intoxication. Eroded shot eviden t in radiographs taken 11 days post-dosing indicated acute exposure to the constituent metals, but no dosed or undosed birds died during the trial. Behavior of dosed and undosed ducks (both n = 20) was normal t hroughout the trial, and no differences were detected in food consumpt ion (P = 0.52, beta = 0.39) or body mass change (P = 0.71, beta = 0. 1 5) relative to treatment. Except for blood calcium, none of 24 hematol ogy or blood chemistry variables measured 3. 11, 21, and 32 days post- dosing differed (P greater-than-or-equal-to 0.09, beta = 0.16) between dosed and undosed birds. Differences in blood calcium (P = 0.02, beta = 0.12) were judged to be unrelated to shot exposure. No gross lesion s were observed during postmortem examinations, nor did histopathologi cal examinations reveal any evidence of toxicity or tissue damage. Tin and tungsten were not detectable (<6 ppm) in kidney or liver samples. Bismuth concentrations in kidney and liver (< 16 ppm) were near detec table limits and did not differ (P = 0.34 and P = 0.22, respectively) between dosed and undosed ducks. We conclude that TBT shot presents vi rtually no potential for acute intoxication in mallards under the cond itions of our study.