Acute Lead (Pb) Toxicosis In Mourning Doves
John H. Schulz, Missouri Department of Conservation, Resource Science Center, 1110 South College Avenue, Columbia, MO 65201; (573) 882-9909; FAX (573) 882-4517; John.H.Schulz@mdc.mo.gov
Joshua J. Millspaugh, Department of Fisheries and Wildlife Sciences, University of Missouri, 302 Anheuser-Busch Natural Resources Building, Columbia, MO 65211
Alex J. Bermudez, University of Missouri, Veterinary Medicine Diagnostic Laboratory, Columbia, MO 65211
Lisa G. Britt, University of Missouri, Veterinary Medical Teaching Hospital, Columbia, MO 65211
Sherry Gao, Missouri Department of Conservation, Resource Science Center, 1110 South College Avenue, Columbia, MO 65201
Thomas W. Bonnot, Department of Fisheries and Wildlife Sciences, University of Missouri, 302 Anheuser-Busch Natural Resources Building, Columbia, MO 65211
Lucas J. Miller, Department of Fisheries and Wildlife Sciences, University of Missouri, 302 Anheuser-Busch Natural Resources Building, Columbia, MO 65211
Long-term declines in several small game populations have prompted many wildlife managers to enhance mourning dove (Zenaida macroura) shooting field opportunities, especially on public lands located near urban population centers; the amount of Pb shot deposited on and around these fields is considerable. Previous evaluations have suggested a low level of risk associated with the deposition of Pb shot on public hunting areas focusing on low dosages corresponding to low chronic exposure; i.e., a chronic Pb toxicosis hypothesis. Other evidence exists, however, demonstrating a rapid and acute poisoning scenario in mourning doves explaining why few doves are found with multiple Pb pellets in hunter-killed bags; i.e., an acute Pb toxicosis hypothesis. Our objective, therefore, was to determine the level of Pb exposure at which acute Pb poisoning occurs, and the effects of mitigating factors (e.g., temperature). We conducted 3 trials with 60 doves per trial. We used a 7-day pre-treatment period followed by a 21-day post-exposure monitoring period. We had 6 treatments (2, 4, 8, 12, 18, and 24 Pb pellets) and a control group. We collected information on basic survival/mortality, body weight changes, post-treatment x-rays to determine pellet retention, packed-cell volume, heterophil:lymphocyte ratios, blood Pb levels, blood plasma chemistries from all survivors at end of each trial, liver and kidney Pb concentrations, and histopathology on individuals. Because individual doves exhibited variation in Pb pellet retention, we regrouped the birds by the number of pellets observed in x-rays taken at 48 hr post-treatment. Survival rates ranged from 0 to 0.5 (95% CI: 0.284-0.880) for trial 1, 0.125 (95% CI: 0.02-0.782) to 0.765 (95% CI: 0.587-0.995) for trial 2, and 0 to 0.467 (95% CI: 0.272-0.802) for trial 3. In general, the higher the number of Pb pellets retained at 48 hr post-treatment, the lower the survival rate. Results and preliminary conclusions will be presented, along with a description of further on-going research investigating possible differences between Pb and steel pellet selection.