Anticoagulant Rodenticide Effects on Wildlife Systems

Anticoagulant rodenticides have long been deployed to suppress pest rodent populations by disrupting the vitamin K cycle and inducing fatal haemorrhage. While effective against target species, these compounds permeate terrestrial and aquatic food webs, leading to primary poisoning of rodents and secondary poisoning of predators, scavengers and non-target fauna. Second-generation anticoagulants exhibit high potency and persistence, resulting in bioaccumulation in liver tissues and extended elimination half-lives. Wildlife across multiple trophic levels—ranging from fish and waterfowl to raptors, mustelids and small carnivores—now frequently carry measurable residues. Consequences include direct mortality, sublethal effects on reproduction and behaviour, selection for genetic resistance in commensal rodents and disruption of ecosystem balance. The global distribution of usage, differing regulatory frameworks and emerging resistance mutations underscore the need for integrated pest management strategies, targeted monitoring programmes and risk mitigation to safeguard biodiversity while maintaining effective control of pest species.

Research from Nature Portfolio

Recent experimental work has validated reduced-dose brodifacoum baits containing approximately half the previous concentration, demonstrating equivalent lethality in non-resistant house-mouse populations under both laboratory and field conditions. These findings support regulatory moves toward lower-toxicity formulations that may lessen non-target exposure without compromising control efficacy. Complementary genetic surveys have mapped sequence variants of the VKORC1 gene in wild rat and mouse populations, revealing regional patterns of amino acid substitutions linked to resistance against warfarin and related compounds. The observed prevalence of key VKORC1 mutations informs localised resistance management, advises rotational use of different anticoagulant classes and highlights the evolutionary pressure exerted by prolonged rodenticide deployment.

Anticoagulant Rodenticide Effects on Wildlife Systems publication trend

The graph below shows the total number of articles in anticoagulant rodenticide effects on wildlife systems across all publications each year (not limited to Nature Index journals).

Technical terms

Anticoagulant rodenticide: chemical compounds that inhibit the vitamin K–dependent clotting cascade to induce lethal haemorrhage in rodents.

Secondary poisoning: unintended intoxication of non-target species via ingestion of contaminated prey or carrion.

VKORC1: gene encoding vitamin K epoxide reductase, the primary molecular target of coumarin-based rodenticides; point mutations confer resistance.

Bioaccumulation: progressive build-up of chemical substances in an organism over time through continual exposure within a food web.

References

1. Rodenticide contamination of cormorants and mergansers feeding on wild fish. Environmental Chemistry Letters (2024).
2. Significant Turning Point: Common Buzzard (Buteo buteo) Exposure to Second-Generation Anticoagulant Rodenticides in the United Kingdom. Environmental Science and Technology (2024).
3. Anticoagulant rodenticide exposure and toxicosis in bald eagles (Haliaeetus leucocephalus) and golden eagles (Aquila chrysaetos) in the United States. PLOS ONE (2021).
4. Efficacy of rodenticide baits with decreased concentrations of brodifacoum: Validation of the impact of the new EU anticoagulant regulation. Scientific Reports (2019).
5. VKORC1 sequence variants associated with resistance to anticoagulant rodenticides in Irish populations of Rattus norvegicus and Mus musculus domesticus. Scientific Reports (2018).