Lesser White-fronted (Anser erythropus) and Greater White-fronted (A. albifrons) Geese wintering in Greek wetlands are not threatened by Pb through shot ingestion

Abstract

Fecal lead (Pb) levels were investigated in the threatened European population of the Lesser White-fronted Goose (LWfG, Anser erythropus) and of the non-threatened Greater White-fronted Goose (GWfG, Anser albifrons) wintering in two wetland areas in northern Greece in order to assess the potential risk from Pb exposure. Fecal, soil and food plant samples were analyzed. Levels of Pb were normalized using Al concentrations in order to separate the effect of possible ingestion of Pb shot from that of soil or sediment accidentally ingested with food. All concentrations are expressed on a dry weight basis. Geometric means of Pb content in the feces of LWfG were 6.24mg/kg at Evros Delta and 7.34mg/kg at Lake Kerkini (maximum values of 28.61mg/kg and 36.68mg/kg, respectively); for fecal samples of GWfG geometric means were 2.39mg/kg at Evros Delta and 6.90mg/kg at Kerkini (corresponding maximum values of 25.09mg/kg and 42.26mg/kg). Soil Pb was in the range of 5.2–60.2mg/kg (geometric mean=22.6mg/kg) for the Evros Delta and between 13.4 and 64.9mg/kg (geometric mean=28.1mg/kg) for Kerkini.A general linear model fitted to the data showed that Pb levels were very closely dependent on Al levels in the feces from both species and at both sites indicating soil or sediment were the only significant source of Pb; species and site, as well as their interaction, were not statistically significant factors. For both species and at both sites exposure to Pb was evidently very mild and the observed levels of Pb were well below the proposed thresholds for lethal or sublethal effects of Pb poisoning. Soil ingestion appeared to gradually increase from October to December for LWfG at Kerkini, corresponding to a gradual depletion of their food source.