Sussex researchers find pesticide use is linked to garden bird decline
By: Lauren Ellis
Last updated: Monday, 6 February 2023
Pesticide use by British gardeners is playing a significant role in the declining populations of our songbirds, as shown by the first study of its kind, published in Science Of The Total Environment. The study, conducted by researchers at the University of Sussex, shows that gardeners who use pesticides can expect to see fewer birds. This is especially true of house sparrows, whose numbers were 25 percent lower in gardens where commonly-available glyphosate was used (known by their brand names such as Roundup or Gallup). However, the research confirms positive news that providing bird-friendly habitats in gardens increased the number of species recorded, and the abundance of individual species.
The study, supported by charity, SongBird Survival, drew on data gathered by the British Trust for Ornithology which organises Garden BirdWatch – a citizen science garden bird recording scheme. It examined information on pesticide use and garden management from 615 garden owners. The owners recorded which brands or products they used, revealing that 32 percent of gardens used pesticides, and that glyphosate-based herbicides made up over half of those applications (53 percent). In gardens where metaldehyde slug pellets were used, house sparrow numbers were down by almost 40 percent.
Professor of Biology at the University of Sussex, Prof Dave Goulson, known for his work on bee ecology and insect-friendly gardening, supervised the research.
Professor Goulson of the School of Life Sciences, at the University of Sussex explains:
“The UK has 22 million gardens, which collectively could be a fantastic refuge for wildlife, but not if they are overly tidy and sprayed with poisons. We just don’t need pesticides in our gardens. Many towns around the world are now pesticide free. We should simply ban use of these poisons in urban areas, following the example of France.”
Author of the study, Cannelle Tassin de Montaigu, a PhD researcher within the School of Life Sciences at the University of Sussex, says:
“It’s encouraging to find that simple measures, such as planting native shrubs and trees and creating a pond, together with avoiding the use of pesticides, really make a measurable difference to the number of birds you will see in your garden.”
SongBird Survival funds high quality science to better understand why Britain’s songbird numbers have fallen by around 50 percent in 50 years. As birds rely on the entire food chain for survival, gardeners concerned with biodiversity loss should rethink their use of pesticides and increase bird-friendly habitats in their gardens via the tips below.
Susan Morgan, the charity’s CEO, adds:
“We’re still trying to understand the factors behind the tragic loss of British songbirds, so we are delighted this new study by the University of Sussex sheds light on why, and how we can help. Brits love their gardens, and as a nation of bird lovers, we must ‘think biodiversity’ and do our bit: Avoid using toxic chemicals or else we’ll continue to see house sparrows, chaffinches, tits and other small birds continue to disappear, their songs silenced forever.”
Bird exposure to harmful pesticides comes in both direct and indirect forms, whether through consumption of contaminated food and/or water, absorbing pesticides through the skin or through a decline in numbers of their insect prey.
Norwich-based entomologist, Ian Bedford, gives talks on how gardeners can support insects in environment-friendly ways. He says:
“A common question I’m asked by gardeners at this time of year is, ‘How can we control plant pests such as aphids and vine weevils without using toxic pesticides in our gardens?’ The answer is to try using environmentally friendly products instead, that deter or block plant pests from susceptible plants instead of killing them. And this will be important if we are going to use our gardens to help restore Britain’s rapidly declining biodiversity, since the creatures we call ‘the plant pests’ are also an essential food source for many other wildlife. Nowadays, there are many non-toxic products that could be used as an alternative to chemicals, so I would certainly encourage Garden retailers to stock a selection of these in their stores and make a real difference in the choices gardeners make.”
SONGBIRD SURVIVAL’S 5 TIPS FOR GARDENERS TO SUPPORT BIRDS
- Ditch the pesticides! The study found that using pesticides is associated with 12 percent lower house sparrow abundance.
- Plant berry bushes to provide natural food and shelter, increasing garden ‘quality’.
- Have a water source in your garden e.g. bird bath or a pond (which encourages invertebrates).
- Hedges made up of different species which flower at different times of the year provide year-round food and shelter for our songbirds e.g. brambles, hazel, honeysuckle.
- Plant flowers that encourage insect life and songbirds e.g. sunflowers, jasmine, fennel, teasel.