Gillian Lloyd
Feeding garden birds safely
What’s the problem?
Recent research conducted by Conservation Scientists at RSPB, supported by other organisations including the British Trust for Ornithology, has highlighted that some of our much-loved garden birds, particularly greenfinches and chaffinches, have seen steep population declines over recent decades. One of the main causes is a disease called trichomonosis, which spreads easily where birds gather closely together, such as at feeders, bird tables and bird baths.
The disease affects a bird’s throat, making it difficult to swallow food and water. Infected birds may regurgitate food, spreading the parasite and infecting other birds.
Because natural food such as insects, berries and seeds are more widely available during the spring and summer months, the benefits of feeding birds at this time are lower, while the risks of disease transmission are higher.
How you can help?
You can make a real difference by feeding birds seasonally and safely. Small changes, made by lots of people, can help protect garden birds.
Feed seasonally
- From 1 May to 31 October, pause filling feeders with seeds and peanuts, as these attract larger gatherings of birds at a time when disease risk is highest.
- From 1 November to 30 April, when natural food is scarcer, you can safely feed a wider range of foods, including seeds and peanuts.
- All year round, you can continue to offer small amounts of mealworms, fatballs or suet.
Feed safely
- Keep feeders and bird baths clean. Wash them at least once a week with hot, soapy water and a wildlife‑safe disinfectant.
- Move feeders regularly to prevent a build‑up of droppings and old food beneath them.
- Avoid bird tables and flat feeders, which allow contaminated food to accumulate and build up which increases the risk of disease spreading.
- Feed little and often, and clear away any spilled seed or husks.
- Change bird bath water daily and clean baths weekly to stop germs building up.
Provide natural food
The best long‑term way to help birds is to create natural food sources.
Birds have diverse diets, with most feeding on different things throughout the year. They’ve evolved to take advantage of what’s available.
Leave some areas a little wilder to encourage insects, which are essential food for many birds, especially in spring and summer. Insects, worms and other invertebrates are essential for most birds, especially in the breeding season when they’re raising their young.
What we are doing on our nature reserves
To help protect bird health and reduce the risk of disease spreading, we are changing how we feed birds on our nature reserves.
From 1 May to 31 October, we will not be putting up bird feeders.
This is the time of year when disease risk is higher and natural food is more readily available. This approach follows the latest scientific guidance by our friends at the RSPB and supports our commitment to wildlife conservation and recovery.
FAQs
What is trichomonosis?
Garden bird trichomonosis is caused by a microscopic parasite (Trichomonas gallinae) that infects the throat and gullet, forming lesions that make it difficult or impossible for birds to swallow food and water. As a result, affected birds often become weak and emaciated and may eventually die from starvation.
The parasite is spread through saliva and regurgitated food, either directly through close contact such as adults feeding their chicks, or indirectly when birds consume contaminated food or water at feeders and drinking areas.
What species does trichomonosis affect?
Trichomonosis has caused serious declines in greenfinch populations, with the species now on the UK Red List as a result of disease-related losses. Chaffinch numbers have also fallen significantly, and there is growing concern that the disease may now be contributing to rapid declines in bullfinches. While some species have been more heavily affected, trichomonosis can infect a wide range of garden birds.
Why has the advice changed?
Conservation scientists at the RSPB have reviewed the evidence on the pros and cons of feeding birds in our gardens. This review found strong evidence that supplementary feeding can promote the spread of disease, including the trichomonosis parasite.
Feeding concentrates birds at feeders and water dishes, making disease transmission more likely, particularly during summer and autumn. For this reason, the RSPB, alongside other conservation organisations including the Trust, now advises feeding birds seasonally and safely.
We recommend pausing seed and peanut feeding between 1 May and 31 October. Small amounts of suet, fatballs or mealworms (soaked in water during spring and summer to make them easier to eat for nestlings) can still be given. To further reduce the risk of disease, please only put out small quantities of food, clean feeders regularly, avoid feeders with flat surfaces, and only provide water if it can be changed daily.
Why do seeds and peanuts cause an issue for garden birds?
Finch species prefer to eat seeds, and if seeds aren’t available, they will divert to peanuts. As finches rarely consume fat and suet (without embedded whole seeds), evidence suggests these foods to be low risk as a source of trichomonas transmission. For these reasons, we advise feeding garden birds safely and feed seasonally.
Why is it ok to feed birds seed and peanuts in the winter?
Although trichomonosis occurs year-round, the risk of an outbreak is relatively low during winter because cold weather kills the trichomonas parasite. Evidence from our friends at the RSPB shows that the risks of trichomonosis outbreaks in UK gardens are highest during August-November, intermediate during April-July and lower during December-March.
Should we stop feeding garden birds altogether?
Evidence shows that feeding birds in winter is often beneficial, particularly during colder weather when natural food is scarce. The March–April “hungry gap” is another important time to support seed‑eating birds.
While trichomonosis can occur year‑round, the parasite is less likely to survive in cold conditions, meaning the risk of disease outbreaks is lower during winter.
Why are 'flat feeders' a problem?
The RSPB’s evidence review found that bird tables and other flat‑surface feeders carry the highest risk of spreading disease. Birds infected with trichomonosis often perch on flat surfaces while trying to feed. Because the disease makes swallowing difficult, they may regurgitate contaminated food onto the feeding surface, where it can then be picked up by healthy birds.
Even regular cleaning cannot fully prevent this risk. For this reason, the advice is to not use any flat‑surface feeders of any kind, including bird tables and window feeders.
Will this impact the species that benefit from supplementary feeding?
The available evidence suggests that stopping the provision of seeds and peanuts is unlikely to have a significant impact on bird species with currently strong populations. For example, blue tits feed their young primarily on insects rather than seeds.
The Trust, alongside the RSPB and other conservation organisations, is also encouraging people to manage gardens and green spaces in ways that support birds naturally, by providing more of the plants and habitats that produce the food they need.
Why should water be changed daily?
Evidence shows that trichomonosis parasites can survive in water, making shared water sources a potential route for disease transmission in gardens.
Reducing the sharing of water by changing bird bath water daily and using fresh tap water can help lower the risk of spreading disease.