2025/06/10 by María Escobar-González, Jordi Feliú, Nuria Vallverdú-Coll +5 · 1 voice
Environmental Science · #Environmental Toxicology and Ecotoxicology #Heavy metals in environment #Mercury impact and mitigation studies
paper · doi:10.1016/j.envpol.2025.126650
openalex publication_date 2025/06/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/25
The ban of lead shot for hunting over wetlands at national and continental scales is essential to reduce the risk of lead poisoning in waterbirds, but the high persistence of lead shot in wetland sediments highlights the need for exploring additional mitigation measures. Grit supplementation has been proposed as a method to reduce the probability of lead shot ingestion by waterbirds, that would add to the regulatory actions. Here we hypothesize that (1) the lead shot ban would reduce lead shot ingestion and (2) grit supplementation would reduce overall shot ingestion (lead + steel) in waterfowl. To test this, waterbirds harvested by hunters during the pre-ban (seasons 1991/1992 to 1995/1996, n = 379), post-ban (seasons 2007/2008 to 2008/2009, n = 254), and post-ban plus grit supplementation (seasons 2009/2010 to 2014/2015, n = 1378) periods were monitored in the Ebro delta (Spain). Grit supplementation was performed in collaboration with local hunters to achieve a grit particle:lead shot pellet proportion above 2:1. Lead shot ingestion prevalence declined by 29.1-77.0 % in the five granivorous species of ducks with the highest prevalence of lead shot ingestion before the ban (i.e. Northern pintail, common pochard, mallard, Northern shoveler and common teal). Shot pellet ingestion (lead + steel) decreased by 33.8 % and 53.4 % during the grit supplementation period in the Northern pintail and common pochard, respectively. We highlight the need for monitoring the lead shot ban compliance and its effectiveness to reduce lead poisoning in waterbirds because other mitigation actions, such as grit supplementation, may be necessary in the short to medium-term before lead shot pellets disappear from wetlands or become unavailable for birds.