Pet Flea Treatments Are Poisoning Wild Birds: Study

High levels of harmful pesticides from pet flea treatments in birds’ nests lined with animal fur is leading to the increased mortality rate of chicks.

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Great tit (Parus major), Lancashire, UK. (Credit: Francis Franklin / CC BY-SA 4.0)

A recent study reveals that pet flea and tick treatments are poisoning wild birds. The study found that songbirds that collect and line their nests with pet fur are at greatest risk.

“No nest was free from insecticides in our study, and this significant presence of harmful chemicals could be having devastating consequences on the UK’s bird populations,” said the study’s lead author, ecotoxicologist Cannelle Tassin de Montaigu, a post-doctoral researcher at the University of Sussex, where she specializes in ecotoxicology and conservation ecology.

“Our research shows that, based on the chemicals detected, veterinary flea and tick drugs are the most likely source of contamination,” Dr Tassin de Montaigu added.

Graphical Abstract. (doi:10.1016/j.scitotenv.2025.178439)

Dr Tassin de Montaigu and collaborators came to this conclusion after analyzing 103 blue tit and great tit nests for the presence of 20 different insecticides. They detected 17 of these poisons…