Research Project

Gardens for birds

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Over 87% of homes (22.7 million households!) are estimated to have access to a garden here in the UK. That’s a total size equal to more than twice the size of London.

These gardens are amazing corridors for wildlife in an urban landscape and could hold a lot of potential for managing the biodiversity crisis.

In this research project we wanted to understand the role our gardens and garden owners play in the urban environment for songbirds and what we can do to encourage wildlife to flourish.

The Project

Our research project working with the University of Reading started in 2014, funding a PhD student. The research aimed to understand more about garden owners and the effect of supplementary feeding on predation rates on garden birds. We also wanted to understand how our domestic pets, feeding habits and man-made materials which are left out can affect bird nesting and reproduction.

For many people who live in urban areas, feeding birds is one of the best ways for them to connect with nature and wildlife. Over 58% of people in the UK provide food for birds, with over £279 million spent last year on outdoor bird food. Conservative estimates suggest that over 30 million birds could survive on this food alone. However, there has been little research conducted into if supplementary feeding could also have unintended negative consequences.

Predators may be attracted to the high densities of birds congregating by feeders, and therefore more likely to predate nests that are close-by. Our research wanted to find ways to mitigate these issues and offer solutions to keep our garden birds happy and healthy.

Using a combination of citizen science, GPS location tags for cats, bird feeders, cameras and artificial nests to study predation, we specifically wanted to know:

  • What are the effects of attracting large numbers of birds to garden feeders?
  • Does bird feeding affect songbird disease, predation or productivity?
  • How can we increase garden bird survival, productivity or diversity?

Sir David Attenborough said on gardens during the pandemic:

"I've certainly spent more time in my garden listening to birds, than I have for a very long time. A lot of people have been surprised by that - a lot of people have suddenly realised what deep, profound joy can come from witnessing the rest of the world - the natural world."

The Results

  • Cats range a median of 1.28 hectares (just a bit bigger than Trafalgar square) from their homes. To protect Sites of Special Scientific Interest or areas of conservation concern, a minimum buffer of 335m would be suggested in future housing developments.
  • Unguarded feeder visits were dominated by grey squirrels at 43.9% of visits compared to guarded feeders 9.3%. Small birds were more likely to visit guarded feeders, where they were not in competition with corvids and squirrels.
  • Magpies regularly visited unguarded feeders, but very rarely visited empty or guarded feeders. Jays rarely visited feeders at all but were responsible for the predation of more than a quarter of artificial nests.
  • Artificial nests near filled feeders were predated 5 times more than the nests near empty feeders.
  • Grey squirrels prefer to feed on peanuts, whereas small birds favoured seed feeders. 2 adult grey squirrels could be fully supported by the levels of feeder use seen in this study.
  • 25% of great tit nests used man-made materials to construct them. Blue tits rarely used these material (1-2%) except when nesting in gardens (16%). These materials were associated with higher levels of fleas in nests.

The Solutions

We have gained valuable insight from our gardens for birds research project, showing that providing food for garden birds can increase the levels of nest predation.

However, there are easy solutions to manage these issues and we would advise that you remember these simple steps:

  1. 1. Choose to use food specific to the birds you want to attract, so more food goes to the birds you want to support rather than the squirrels
  2. 2. Your environment is key when attracting garden birds. Plant bird-friendly flowers, trees and shrubs and locate your feeders as far away as you can from known nests or nest boxes. 40m is best, but as far as you can manage!
  3. 3. Protect your feeders from potential predators by using guards, bird baffles or use squirrel/magpie deterrents to discourage them from visiting your feeders and monopolizing the food.
  4. 4. Clean feeders regularly and clean nest-boxes after the breeding season is over and they are unoccupied to reduce disease transmission. If you provide nesting material for birds, make sure it is natural to reduce flea levels in nests. Don’t provide animal fur unless your pets have not been treated with flea and tick ointments.
  5. 5. To protect your nestboxes from predators, install a nest box without a perch, as these can give predators access to nestboxes that would be otherwise hard to reach. Nestboxes constructed of woodcrete have been found to be predator proof and provide a great home for your feathered friends.
  6. 6. Keep your cat in during the night if you can from #DuskTillDawn to give our birds a chance through the breeding season. Other options include catios and  fencing by ProtectaPet that keep cats in gardens and reduce roaming.

Our urban gardens can provide a safe haven for wildlife, whether your garden is large or small. Following these tips can help to mitigate negative consequences caused by supplementary feeding.

To further encourage wildlife into your local area, read more tips and advice.

Meet our scientists

What is a Songbird?

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Dr Hugh Hanmer

Research Ecologist- BTO

Hugh holds a BSc Zoology (Hons) degree and an MRes in Environmental Biology from the University of St Andrews in Scotland as well as his PhD from Reading on the ecology of urban birds.

Dr Martina Cecchetti

Postdoctoral researcher - University of Exeter

Martina Cecchetti has put in so much work on our study into Cats and Their Owners, alongside Dr Sarah Crowley and Prof. Robbie Mcdonald on the University of Exeter team.



Hanmer, H.J., Thomas, R.L., Fellowes, M.D.E. (2016) Provision of supplementary food for wild birds may increase the risk of local nest predation. Ibis. 159:158-167.

Hanmer, H.J., Thomas, R.L., Fellowes, M.D.E. (2017) Urbanisation influences range size of the domestic cat (Felis catus): consequences for conservation. Journal of Urban Ecology. 3(1):1-11.

Hanmer, H.J., Thomas, R.L., Beswick, G.J.F., Collins, B.P., Fellowes, M.D.E. (2017) Use of anthropogenic material affects bird nest arthropod community structure: influence of urbanisation, and consequences for ectoparasites and fledging success. Journal of Ornithology. 1-15.

Hanmer, H.J., Thomas, R.L., Fellowes, M.D.E. (2018) Introduced Grey Squirrels subvert supplementary feeding of suburban wild birds. Landscape and Urban planning. 177:10-18.


Davies, Z.G., Fuller, R.A., Loram, A., Irvine, K.N., Sims, V., Gaston, K.J. (2009) A national scale inventory of resource provision for biodiversity within domestic gardens. Biological Conservation. 142:761-771.

Orros, M.E., Fellowed, M.D.E. (2015) Wild Bird Feeding in an Urban Area: Intensity, Economics and Numbers of Individuals Supported. Acta Ornithologica. 50(1):43-58.

PFMA (2022, May 24). PFMA Market Data 2021. Pet Food Manufacturers Association.

See our publication library for more of our research.