Small change, big impact: how to feed your garden birds

There isn’t often a conservation project everyone can play a part in. But now we better understand the unintended consequences of feeding garden birds, there’s a great opportunity for us all to make a difference. Whether you love to see birds in your garden, on your balcony, or on your local patch, here’s how to help.

Encouraging birds to gather around a feeder can have a serious effect on their health. Spread through the saliva of birds, the microscopic parasite Trichomonas gallinae can cause a disease, trichomonosis, which has proved fatal for several garden bird species. This disease has caused the recent worrying declines of Chaffinches and Greenfinches, and our scientists suspect it is likely to be affecting other bird species, too.

Read more about how this disease is impacting Greenfinches.

If you’ve been reading The RSPB Magazine over the past year you may be aware that, as part of the Garden Wildlife Health project, the RSPB has been working to find solutions to this problem. This work has been partly funded by Natural England (NE) through the NE and RSPB Action for Birds in England partnership. It included RSPB scientists taking samples from gardens where finch trichomonosis is suspected, and the Institute of Zoology (IoZ) analysing these to understand how the disease is most likely to spread. At the same time, the British Trust for Ornithology (BTO) has led research looking at how season, weather, bird feeding and local bird abundance may affect these outbreaks, using long-term citizen science data gathered through the BTO Garden BirdWatch project.

Read more about RSPB and partners work on the disease.

“Using bird feeders carries risks and benefits for our birds. Research clearly shows that feeding helps birds get through periods of harsh winter weather,” explains Will Peach, the RSPB’s Head of Conservation Science in England and Wales. “However, by repeatedly attracting many birds to the same location, feeding risks disease spread, which we know has caused widespread mortality amongst several finch species.” The good news is that our scientists believe we can help garden birds with a couple of simple shifts.

Feed seasonally

Although trichomonosis is a threat all year round, the risk of disease spreading is higher during the warmer months. This is also when adult birds will be taking potentially infected food to then feed their young.

From the beginning of May until the end of October, we recommend you pause feeding peanuts and seeds. Gradually reduce the seeds and nuts you put out during April, then stop at the beginning of May. If you want to keep feeding birds during May to October we suggest you only put out small amounts of mealworms or suet. It is natural for many garden birds, such as Blue Tits, to switch from eating seeds to invertebrates during spring and summer. They have evolved to eat what would normally be available to them each season. Soft food such as caterpillars, spiders and worms are also safer to feed to their chicks as they are less likely than nuts and seeds to get lodged in their throats.

The RSPB will pause selling seeds and peanuts for birds between May and October, but will continue to sell suet and mealworms throughout the year.

Feed safer

“Flat feeder surfaces such as seed-catching trays and bird tables should no longer be used, as these increase the risk of disease spread,” says Will.

Research shows that these feeders present the highest risk because they can easily retain regurgitated, damp food and bird faeces. The RSPB removed feeders with flat surfaces from sale in December 2024 as a precautionary measure. The RSPB and other Garden Wildlife Health partners are working together to trial new feeder designs to make bird feeding safer.

Spreading feeders apart and moving them around your garden probably also reduces the risk of disease spread. That helps to mimic the way birds would move naturally between different food sources in the wild, rather than repeatedly returning to the same location.

You can judge how much food to provide by the speed at which it is removed. Food in nut and seed feeders should be eaten within two days to reduce the risk of disease spread. If you find your local birds are not getting through the food fast enough, reduce the amount that you offer.

Bird feeders should be cleaned at least once each week. It’s best to wait until they are empty, then clean thoroughly and refill. Avoid adding new food on top of old food and make sure seed is not accumulating on the ground below feeders. Regular cleaning of feeders can contribute to reducing disease spread, but combining it with the advice above will have a much bigger impact in improving safety for garden birds.

So, we don’t need to stop feeding birds, but by taking these simple precautions we can make a huge difference, slowing the spread of trichomonosis and helping garden bird populations recover. The science will continue to evolve but we must act now. We believe this is the fastest way of limiting how the disease is spread. The RSPB and Garden Wildlife Health partners will continue to monitor the situation and provide updated advice.

“Much of our conservation work is carried out away from where we live, but our own gardens and local green spaces are also vital for wildlife. By switching to seasonal feeding and providing food safely, everyone can help make a difference,” says RSPB Chief Executive Beccy Speight. “This is a unique opportunity for all of us to work together and help give finches a brighter future.”

We recognise this will be difficult for the bird food and bird care industry and it will take time for industry to transition, but we want to work with them to find long-term solutions. We all have a crucial role to play and we hope they will support our policy change and work with us to improve product design, reduce disease risks and promote seasonal, science-based feeding guidance.

We’ll continue to provide guidance on how we can all help garden birds, including the best plants that provide natural food for birds in your garden, balcony or window box, in The RSPB Magazine.

For the latest advice on keeping garden birds healthy, including a guide to cleaning bird feeders, visit our website.

How to feed garden birds seasonally and safely