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New publication looks into the hazardous chemicals impact on Red-breasted Goose at its wintering grounds in Bulgaria

Lead shot is the preferred ammunition for many hunters. It is highly toxic and causes high mortality in many wildfowl, including non-target species, which accidentally ingest spent shot pellets along with grit, used to aid digestion. It was currently unknown if lead poisoning was an issue in Red-breasted Geese, what the potential sources of lead are for this species, or whether lead poses a greater risk in particular parts of the flyway. Therefore the assessment of the risk for lead poisoning was amongst one of the expected results of the AEWA Single Species Action Plan - Result 11 - The severity of threat from lead poisoning evaluated. However the current study went further and looked into the agricultural chemicals to which the geese are exposed as they feed predominantly in cropfields during winter.

The paper addresses two potential causes of decline of this species for the first time: lead poisoning, and contamination from pesticides. The study quantified the densities of spent Pb shot in three wetlands used by the geese in north-east Bulgaria, and analysed the Pb concentration in the faeces of Red-breasted Geese and the more abundant Greater white-fronted Geese Anser albifrons, using Al concentration as an indicator of soil ingestion. Pb shot densities in sediments were low, and we found no evidence for Pb shot ingestion in red-breasted geese. On the other hand, we found that the geese were feeding on wheat whose seeds were treated with four fungicides: thiram, tebuconazole, difenoconazole and fludioxonil, and the two first were even detected in geese faecal samples. Using data on the daily food intake, we estimated the exposure levels of the geese to these fungicides, both by measuring the concentrations remaining on seeds and by estimating the amount used to coat the seeds at the time of sowing. We found that the exposure rates estimated during the sowing period for both geese species can exceed the recognized hazardous doses for thiram, and to a lesser extent for tebuconazole, which indicates that some pesticides may be playing a previously overlooked role in the decline of red-breasted geese.

You can find the whole paper here

Mixed flock of Redbreasts grazing in a field in NE Bulgaria
Fresh faecal samples were collected for the study
Density of lead shots in shallow water was assessed as well
collecting samples from soil and plants