Research shows that over 85% of dog owners used a flea-treatment in the last year. Of these, 36% claimed to let their dog to swim in rivers or streams at least once a month. While we know these treatments end up in water, we don’t know how much further they travel and where they can end up.
Building on the findings of the birds and pesticides research, SongBird Survival is continuing to build the relationship with the University of Sussex by funding the 'Do veterinary drugs harm nesting tits?' project. The project will be done in collaboration with Dr Julia Schroeder at Imperial College London using Silwood Park as the site*.
In January 2024 Dr Cannelle Tassin de Montaigu began a 2-year postdoctoral research project, to explore if spot-on flea treatments could have an impact on the breeding and survival of nesting tits.
Many species of songbird use dog, cat and livestock hair in their nests, often as cushioning before laying eggs. This project hypothesises pesticide treated pet and livestock hair could be present within nests, potentially affecting eggs and chicks.
Research goals:
Using the Imperial College London site at Silwood Park*, this study will:
*The blue tit project at Silwood Park operates under the Home Office Project Licenses of Dr Julia Schroeder: PPL 7009092: Sept 2016-Sept 2021 and PPL PP5873078: Sept 2021-Sept 2026.
Looking at 103 nests from blue tits and great tits, the initial results of this research found:
Further analysis of the same nests found significant positive correlations between insecticide concentrations found in the nest fur lining and those in unhatched eggs and dead chicks. These results offer some of the first evidence of transfer of insecticides from nest linings into eggs and chicks.
The results of this project strongly suggest that chemicals originating in veterinary drugs are contaminating birds’ nests and reaching their offspring. We are a nation of pet lovers and many pet owners will be using the ‘spot-on’ flea treatments for cats and dogs as they look to keep their pets healthy. Many pet owners will be very concerned to hear that these veterinary drugs are potentially having such a negative impact on songbird populations.
We are therefore calling on the government for:
As recommended by the British Veterinary Association, pet owners and vets should have informed discussions about their pet’s flea and tick treatments to risk-assess when treatments are needed, taking into account animal, human and environmental health risks, in addition to lifestyle factors.
SongBird Survival recommends:
Professor Goulson studies the ecology, behavior and conservation of bumblebees, with an interested in pollinators and pollination more generally, and particularly in the sustainable management of pollinators in agro-ecosystems. .
Cannelle is a post-doctoral researcher at the University of Sussex, specialising in ecotoxicology and conservation ecology. Her current research focuses on the impact of veterinary drugs (such as spot-on dog treatments) on the health of nesting tits.
Tassin de Montaigu, C. et al., (2026) Transfer of veterinary parasiticides from the fur lining bird’s nest to eggs and chicks. Environmental Science and Pollution Research. https://doi.org/10.1007/s11356-026-37654-7
Tassin de Montaigu, C., Glauser, G., Guinchard, S., Goulson, D. (2025) High prevalence of veterinary drugs in bird's nests. Science in the Total Environment. https://doi.org/10.1016/j.scitotenv.2025.178439
Perkins, R., Goulson, D. (2023) To flea or not to flea: survey of UK companion animal ectoparasiticide usage and activities affecting pathways to the environment. PeerJ. 11, 15561, 10.7717/peerj.15561
Perkins, R, Whitehead, M, Civil, W., Goulson, D. (2021) Potential role of veterinary flea products in widespread pesticide contamination of English rivers. Science of the Total Environment. 755: 143560
Wells, C., Collins, C.M. (2022) A rapid evidence assessment of the potential risk to the environment presented by active ingredients in the UK’s most commonly sold companion animal parasiticides. Environmenta Science and Pollution Research. 29: 45070-45088.
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