Excessive lead burden among golden eagles in the Swiss Alps

Abstract

Fragments from lead ammunition pose a poisoning risk for predators like golden eagles that scavenge on non-retrieved carcasses or offal left behind by hunters. Three golden eagles were found in the Swiss Alps with an acute lead poisoning. To investigate whether the few cases of lead-poisoned golden eagles are exceptional events or whether a substantial proportion of the Alpine golden eagle population is affected by lead at sublethal levels, we measured body burdens in golden eagles from Switzerland in comparison to eagle owls from the same area and to their respective prey. These two raptor species differ in their food as eagle owls feed on live-caught prey. Lead levels in soft tissues were significantly higher in golden eagles (median 1.14 μg g −1 dry weight in liver, 0.99 μg g −1 in kidney) than in eagle owls (0.14 and 0.23 μg g −1 ). Bones of golden eagles contained 10 times more lead (median of 12.45 μg g −1 dry weight) than owl bones (1.28 μg g −1 ), which represent substantially higher levels than previously reported for golden eagles. Bones of prey of both golden eagles and eagle owls had low lead concentrations. In order to investigate whether the sublethal lead of golden eagles originates from ammunition or from generic environmental contamination, we examined lead isotope ratios. Lead isotope signatures of golden eagle bones were very similar to those of ammunition, but differed from the signatures of bones of their prey, eagle owls and soil. Isotope signatures did not change with increasing bone lead concentration in golden eagles or any other group examined. These findings indicate that in the Alps, most golden eagles take up lead from spent ammunition in carcasses or their offal in sublethal quantities throughout their life and a few in lethal quantities leading to acute lead poisoning.

Can Ingestion of Lead Shot and Poisons Change Population Trends of Three European Birds: Grey Partridge, Common Buzzard, and Red Kite?

“…Additionally, if concentrations of lead in tissue are used to determine the potential ultimate percentage of mortality due to lead shot ingestion (as we did for raptors), one should consider whether or not the percentage might be overestimated because it might include lead poisoning from lead bullets or non-lead-shot sources. For example, lead bullets, instead of lead shot, were estimated to have caused 5.1% annual mortality in California condors ( Gymnogyps californianus ) [ 78 ] and are the main lead source for golden eagles poisoned by ammunition in the Swiss Alps [ 79 ]. Leaded gasoline appeared to poison European kestrels ( Falco tinnunculus ) [ 80 ].…”

Lead Exposure in the Critically Endangered Bearded Vulture (Gypaetus barbatus) Population in Southern Africa

“…Consumption of prey containing lead shot or bullet fragments is generally perceived as the primary source of lead poisoning in raptors (Kendall et al 1996, Mateo et al 1999, Clark and Scheuhammer 2003, Fisher et al 2006, and for a number of species this has been confirmed through isotopic analysis (Finkelstein et al 2014, Madry et al 2015. The high velocities of modern firearms cause lead-based bullets to fragment widely along the wound tract (Stroud and Hunt 2009).…”

La contaminación por munición de plomo en Europa: el plumbismo aviar y las implicaciones en la seguridad de la carne de caza

“…Otra especie muy afectada, como se puede observar por el número de casos (Figura 5) es el águila real (Aquila chrysaetos). Casos de intoxicación en esta especie han sido descritos en toda Europa, con diez casos en Suecia (Borg 1975), seis en España (Foto 5; Cerradelo et al 1992;Mateo et al 2011), cinco en Suiza (Kenntner et al 2007;Madry et al 2015), dos en Alemania (Bezzel y Fünfstück 1995) y uno en Austria (Zechner et al 2005). Las tasas de ingestión que se obtuvieron en un estudio en Noruega fueron extremadamente elevadas, donde el 70% de las egagrópilas contenían perdigones de plomo (Tabla 7).…”