Conservationists are calling for restrictions on pet flea control after a study found that songbird feathers are extensively contaminated with a substance that can damage the birds’ brains and kill unborn chicks.
Almost all tested feather samples from five common UK garden bird species contained either permethrin, imidacloprid or fipronil. Although both of these insecticides are banned for agricultural use, they are still common in treating ticks and fleas on pets.
Fipronil and imidacloprid are known to impede reproductive success and disrupt neurological function in garden birds, while permethrin was found to slow growth rates and suppress feather growth in wild bird chicks, the researchers said.
The findings come after dozens of veterinary professionals, wildlife charities and academics signed an open letter calling on the government to address “systemic failings in veterinary medicine regulation”.
“Pet owners should have confidence that the products they use protect their pets,” they wrote in a letter to Environment Secretary Emma Reynolds.
Last week, the agency launched an eight-week consultation to ban UK pet owners from buying over-the-counter medicines for cats and dogs, in response to concerns about the impact on songbirds, fish and other aquatic life.
Over 80% of dogs and cats in the UK are treated for fleas and ticks at least once each year. Many are applied monthly as “spot-on treatments” and then washed into sewage, rivers, and soil.
In the latest study, funded by conservation charity Songbird Survival, researchers at the University of Sussex carried out chemical analyzes of feathers collected by volunteers belonging to the blackbird, blue tit, chaffinch, dunnock and goldfinch species.
The study also examined goldfinch feathers.
Analysis found pesticides in 100% of the feather samples, including permethrin in 98%, imidacloprid in 88%, and fipronil in 72%. Surprisingly, chlorpyrifos, which is banned in the UK due to evidence of negative effects on children’s cognitive development, was detected in 96% of the samples.
“[Our study]shows that wild animals are chronically exposed to pesticides,” said Dr. Canel Tassin de Montagu, one of the study authors.
Although the effects of pesticides on newborn songbirds have not yet been fully investigated, Tassin de Montaigues said, “Given the neurotoxicity of fipronil and imidacloprid, even low levels of chronic exposure during early development can cause irreversible physiological or behavioral impairments in chicks.”
The problem, she said, is not that you don’t use flea and tick pesticides at all, but that you use them too often for prevention.
“We don’t treat children for lice every month. We treat them when necessary, but not on pets. And that should change.”
Susan Morgan, CEO of Songbird Survival, said the researchers’ findings were “very alarming” and an effective first step would be to make flea treatments prescription-only.
“Putting a label on a box is not enough; it requires an informed conversation between veterinarians and pet owners to protect pets, homes, and the environment,” Morgan says.
A Defra spokesperson said: “The Government is committed to restoring nature and cleaning up our rivers. We take water pollution from flea and tick control extremely seriously and have recently launched an evidence campaign to help us decide how best to tackle this problem, including changes to the way we sell.”
