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Second-Generation Anticoagulant Rodenticides Were Detected in 90% of Red Foxes Sampled in England

Wild red fox in London, England
Conservation · Threats

A study first published in 2026 found widespread exposure to second-generation anticoagulant rodenticides in red foxes (Vulpes vulpes) sampled in England. These rodent poisons disrupt the vitamin-K cycle and therefore blood clotting; foxes can be exposed indirectly when they eat contaminated rodent prey. Rodenticides were detected in 90% of 181 fox liver samples collected between 2013 and 2020.

The researchers screened liver tissue from 181 red foxes and 100 European hedgehogs (Erinaceus europaeus) using liquid chromatography–tandem mass spectrometry, a laboratory method that separates and identifies very small amounts of chemical residues. Anticoagulant rodenticides were also detected in 62% of hedgehog samples. Among all animals with detectable anticoagulants, 83% contained more than one compound, consistent with repeated or cumulative exposure.

High residues indicate concern, not a diagnosis of poisoning

For red foxes, 64% of samples contained summed anticoagulant concentrations above 100 ng/g, a reference value commonly used in stewardship monitoring and as an indicator of potential poisoning. The threshold is not diagnostic by itself: sensitivity differs among species, toxic effects may occur below it, and wildlife poisoning is normally assessed from residues together with signs such as haemorrhage. The study therefore demonstrates widespread exposure but does not show that 64% of the sampled foxes were clinically poisoned. It found no significant association between fox exposure and geographical region or sex.

No clear reduction after the stewardship scheme

The authors found no evidence within their convenience sample that overall second-generation anticoagulant exposure had declined following the introduction of the UK rodenticide stewardship scheme in 2016. Brodifacoum was actually more likely to be detected in samples collected after the scheme began, but the opportunistic sample design means this cannot be attributed to the scheme itself. The authors conclude that exposure remains widespread in non-target British mammals and support more structured monitoring.

Sources and image credit

  1. Seilern-Macpherson, K., Lawson, B., Charman, S., Jones, S., Rainford, J., Macarthur, R., Kent, A. J., Cunningham, A. A., & Barnett, L. (2026). Exposure to second-generation anticoagulant rodenticides is widespread in the non-target British wild mammals Erinaceus europaeus and Vulpes vulpes. Science of the Total Environment, 1043, 181927. https://doi.org/10.1016/j.scitotenv.2026.181927Primary research article with article date 5 June 2026; the journal issue is dated 10 August 2026. Liver samples from 181 red foxes and 100 European hedgehogs collected in England in 2013–2020 were screened for pesticides. Anticoagulant rodenticides were detected in 90% of foxes and 62% of hedgehogs; 64% of fox samples exceeded the commonly used 100 ng/g summed-concentration reference value, and the convenience sample showed no evidence of reduced exposure after the UK stewardship scheme began in 2016.

Image: Ryan Hodnett — wild red fox (Vulpes vulpes) in London, England, photographed 29 October 2023; Wikimedia Commons / iNaturalist; representative British species image, not a fox sampled in the rodenticide study · CC BY-SA 4.0 · Source

About this content: This story was produced with AI assistance within an editorial workflow developed by Wildlife Vagabond. Editorial responsibility remains with Wildlife Vagabond.How AI is used

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