Incidence of lead ingestion in managed goose populations and the efficacy of imposed restrictions on the use of lead shot

Lead is a toxic heavy metal that when ingested can cause death or sub-lethal fitness effects. Despite its toxicity, it is still widely used in recreational and management shooting globally. To reduce the impacts of lead on wildfowl, recent European Union legislation has banned the use of lead shot in and around wetlands from 2023. Understanding the effectiveness of such mitigation is vital to inform future policy. On Islay, Scotland, the licensed shooting of Barnacle Geese Branta leucopsis to reduce agricultural damage has adhered to the ban on use of lead shot over Ramsar-designated wetlands legislated in Scotland in 2004. On average 2380 lead cartridges were fired annually between 2005 and 2020 outside designated wetlands, where Barnacle Geese and other wildfowl forage. From faecal samples, it is possible to infer whether birds have ingested lead and are therefore potentially suffering from lead poisoning. After sampling faeces from Barnacle Geese (n = 193) and Greenland White-fronted Geese Anser albifrons flavirostris (n = 150) we found only four (1.2%) faecal samples with elevated lead levels that may be indicative of lead shot ingestion. Further post-mortem examinations (n = 102 Barnacle Geese only) and X-ray of live birds (n = 293) revealed similarly low levels of shot ingestion in both species (post-mortem