Lead concentration in the bones of the feral pigeons (Columba livia): sources of variation relating to body condition and death.

This paper reports on lead concentrations in the tarsometatarsi of 84 individuals of adult feral pigeons Columba livia found dead or experimentally captured in Bratislava, Slovakia. The interrelationships between lead concentrations and time of death, place of death, body measurements, sex, condition, and plumage phenotype were investigated. Size and shape of pigeons was not correlated with bone lead contamination. Sex and plumage color and pattern were slightly associated with variation in bone lead levels, females and melanic (urban) phenotypes tending to have higher bone lead concentrations than males and blue-bar (wild) individuals. Birds with antibodies to chlamydiae did not contain significantly higher lead concentrations in the tarsometatarsi than birds without antibodies. Concentration of lead in tarsi was significantly higher in birds dying in winter, compared to birds dying at the end of summer. Chronic lead poisoning probably causes mortality in pigeons in winter. The natural stressor, cold weather, has the capability of exacerbating the effects of lead poisoning, and the mortality is due to lead exposure coupled with cold stress.