Abstract
Eighty-nine birds were found dead in Ogata village in northern Japan, in March 2006. Eighty-eight birds were rooks (Corvus Frugilegus Pastinator), which are migratory birds. Since the use of rodenticide (thallium sulfide and zinc phosphate) in the area where the birds had been found was revealed by a survey, etiological and pathological examinations including elemental analysis were conducted. Elemental analysis showed high concentrations (56-365 μg/g dry weight) of thallium in the lungs, gastric contents, intestines, livers and kidneys. Histopathological examination revealed vacuolar degeneration of hepatic cells and granular and/or hyaline droplet degeneration of renal tubular epithelia. The results suggest that the mass deaths were caused by thallium poisoning.
