Lead poisoning in wild birds from southern Spain: A comparative study of wetland areas and species affected, and trends over time

Abstract

We studied lead (Pb) shot contamination in sediments from the Guadalquivir marshes and six other closed-basin lagoons in Southern Spain that are of major importance for threatened species of waterbirds. Shot densities were relatively low in Doñana, ranging from 0 to 25 shot/m(2) in the top 10 cm of sediments. The density at Medina lagoon (Ramsar site) was 148 shot/m(2), making it the most contaminated wetland known in Europe. Densities in the other five lagoons ranged from 9 to 59 shot/m(2). We studied the prevalence of ingested Pb shot in waterbirds from Doñana and found a lower prevalence in ducks than previously recorded in other Spanish wetlands. Lead shot were also found embedded in tissues of some waterbirds, proving that protected species such as the greater flamingo (Phoenicopterus ruber) and the glossy ibis (Plegadis falcinellus) are subjected to illegal hunting. The prevalence of embedded shot for geese was especially high (44% for trapped birds). Lead shot were detected in 2.8% of the pellets of the Spanish imperial eagle (Aquila adalberti) which usually preys on geese. We found that the prevalence of ingested Pb shot in geese and in Spanish imperial eagles has significantly decreased in recent years, possibly due to restrictions on hunting activity, efforts to remove shot from a sand dune used by geese to obtain grit, and to the high rainfall in Doñana during the last years that permitted waterfowl to stay more within the protected areas.

Effects of lead exposure on oxidative stress biomarkers and plasma biochemistry in waterbirds in the field

“…Pb shot ingestion in hunted birds is positively related to grit size in gizzards, and also negatively related to the abundance of grit in the environment Figuerola et al, 2005). Medina lagoon has low abundance of grit of 4 1 mm, but a high Pb shot density in sediment (Mateo et al, 2007), increasing the risk of Pb shot ingestion for those species selecting grit of 4 1 mm. The elevated Pb exposure observed in the moorhens from Salada lagoon (43%) can be explained by the high accessibility of Pb shot in the sediments due to the low water level at the time of capture.…”

“…In a separate study, we have confirmed using Pb isotopes that Pb shot ingestion causes high Pb levels in waterbird feces from the Medina lagoon (authors, in prep. Mateo et al, 1997Mateo et al, , 2007Mateo, 2009). The results for pochards suggest that the white-headed duck is also exposed to Pb poisoning at Medina lagoon, which regularly holds several hundred individuals of this globally threatened species, and up to 25% of the Spanish population.…”

“…The detection limit was o 0.6 mg/dl of Pb in blood. Blood Pb concentration respectively (Mateo et al, 2007). Additional sampling was carried out in Salada lagoon, a brackish and shallow lagoon of 33 ha with a density of 59 Pb shot/m 2 in the first 10 cm of sediment, located in Puerto de Santa María (Cá diz, 36138 0 40 00 N, 06114 0 10 00 W) 16 km to the west of Medina lagoon (Mateo et al, 2007).…”

Intoxicación por munición de plomo en aves silvestres en España y medidas para reducir el riesgo

“…1). De modo general, las máximas densidades de perdigones en sedimento han sido detectadas en la Laguna de Medina (Cádiz), con una media de 399 perdigones/m 2 en los primeros 30 cm de sedimento (Mateo et al 2007a). Puntualmente podemos encontrar densidades todavía mayores en humedales en los que hay campos de tiro deportivo como es el caso del Parque Natural de El Hondo, donde en una zona se registró una densidad de 1432 perdigones/m 2 (Bonet et al 2004).…”

Use of grit supplements by waterbirds: an experimental assessment of strategies to reduce lead poisoning

“…It is particularly important for red-knobbed coot and the globally threatened white-headed duck (Oxyura leucocephala). Further, ML has the highest density of Pb shot pellets in sediments, resulting from hunting activity, recorded for any European natural wetland, with 399 shot per square metre in the upper 30 cm (Mateo et al 2007).…”