Factors causing variations of lead and cadmium accumulation of feral pigeons (Columba livia).

In order to understand the factors causing variation of lead and cadmium accumulation in tissues of feral pigeons in Seoul and Ansan, Korea, we investigated their age, food items (crop and gizzard contents) as well as environmental factors such as soil, atmosphere, and local traffic density. The results indicate that concentrations of Pb and Cd were highly increased in the order of eggs < chicks < adults. In food analysis, supplementary foods (rice, small stones, domestic scraps, cements, hairs, Styrofoam, etc.) could be considered as factors considering the Pb concentration differences. Concentrations of Cd in foodstuffs, the proportion of crop contents as their major foods could have an influence on the difference of Cd levels from a nutritional viewpoint. The Pb levels in gizzard contents and soil had an effect on the tissue accumulations, these were associated with the volume of vehicular traffic. However, we could not find any differences of Cd concentrations in gizzard contents and soil, although there were significantly different Cd accumulations in target organs of adult pigeons between the study areas. The Pb and Cd levels in tissues did not correspond to atmospheric metal levels.