Blood Lead Concentrations of Free-Ranging North Florida Raptors: 2008–17

Abstract: Whole blood samples for lead analysis were collected from 441 raptors admitted to the Zoological Medicine Service at the University of Florida (US) between 1 January 2008 and 31 December 2017. The species included Bald Eagles (Haliaeetus leucocephalus), Ospreys (Pandion haliaetus), Black (Coragyps atratus) and Turkey (Cathartes aura) Vultures, Barred (Strix varia) and Great Horned (Bubo virginianus) Owls, and Red-tailed (Buteo jamaicensis) and Red-shouldered (Buteo lineatus) Hawks. Our hypothesis was that geography, seasonality, and hunting strategies of these species would all affect the blood lead concentrations. Blood lead concentrations were found to vary significantly between species, with known scavengers having higher values. Additionally, seasonal differences were seen between winter and summer, but the county in which these individuals were found did not alter the blood lead concentrations. We found lead contamination to be a common and considerable problem in Bald Eagles and vultures but not as evident in nocturnal and other diurnal raptors in North Florida. Furthermore, concentrations were highest during winter in this temperate location, suggesting a possible relationship with hunting seasons despite a lack of big game.