New PBMS report published: 'Second-generation anticoagulant rodenticide residues in barn owls 2022'

The current report is the seventh in a series of annual reports that describe the monitoring of Second-Generation Anticoagulant Rodenticide (SGAR) liver residues in barn owls (Tyto alba) in Britain. This work is an element of an overarching monitoring programme undertaken to track the outcomes of stewardship activities associated with the use of anticoagulant rodenticides. The barn owl, a generalist predator of small mammals, is used for exposure monitoring as a sentinel species. The number of barn owls dead and collected across Britain was 88 in 2022, instead of 100 as the previous years, due to the impact of Avian Influenza. The measurement of liver SGAR residues in these barn owls is compared with the residues from 395 barn owls found dead between 2006 and 2012 (referred to as 'baseline years'), prior to changes in anticoagulant rodenticide authorisations and the onset of stewardship.

Overall, there were significant differences in SGAR accumulation in barn owl livers between the baseline years and 2022: a potential reduction of bromadiolone and difenacoum and an increase of brodifacoum residues. However, no significant difference was observed in the sum of SGAR residues. These trends were the same as the previous year. The lack of significant reductions in the sum of SGAR residues suggests that full implementation of stewardship since 2018 has yet to result in a statistically significant reduction in the exposure of barn owls to SGARs.

For the full report (and all of our previous reports), see our Reports pages.

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