The current report is the sixth 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 is used for exposure monitoring as it is considered a sentinel for species that are generalist predators of small mammals in rural areas. The specific work reported here is the measurement of liver SGAR residues in 100 barn owls that died in 2020 at locations across Britain. The residue data are compared with those from 395 barn owls that died between 2006 and 2012 (referred to as baseline years), prior to changes in anticoagulant rodenticide (AR) authorisations and onset of stewardship.
Overall, there were few differences in liver SGAR accumulation between barn owls that died in baseline years and in 2020, the exception being a potential increase brodifacoum residues. The lack of significant reductions in SGAR residues in barn owls in 2020 suggests that full implementation of stewardship since 2018 has yet to result in a statistically significant reduction in exposure of barn owls to SGARs.
For the full report (and all of our previous reports) see our Reports pages.