Garden birds should not be fed seeds and nuts over the summer months, the RSPB has said, in an attempt to reduce the spread of avian diseases.

Bird lovers are being urged to take down their bird feeders between May and October to help birds such as the greenfinch, whose numbers have plummeted after the spread of trichomonosis, a parasitic disease transmitted more easily when birds cluster around feeders in the warmer months.

In new guidance, the RSPB is advising people to “feed safely and feed seasonally” by removing all bird feeders filled with seeds and peanuts and instead offering small amounts of protein such as mealworms, fat balls or suet from 1 May to 31 October, since they tend not to attract clusters of finches and protein is useful for the birds to feed their chicks.

It follows the results of this year’s Big Garden Birdwatch, the world’s largest garden survey with 650,000 participants, which put the greenfinch in 18th place overall. The species, which is now on the red list of endangered British birds, has recorded a 67% decline in average numbers since the annual Big Garden Birdwatch survey began in 1979.

An estimated 6 million greenfinches and chaffinches have died because of the disease in recent years.

“Feeding birds is something millions of us love and value, but the science shows us that birds such as greenfinches have been affected by the spread of disease at feeders,” said Beccy Speight, chief executive of the RSPB. “We’re not asking people to stop feeding, just to feed in a way that protects birds’ long-term health. By making small changes together, we can ensure garden feeding continues to be a positive force for nature.”

While one study estimates that the volume of food put out by Britons could support 196 million garden birds – almost half the total number of wild birds in the British countryside – another found that feeding birds changes the local phosphorus cycle, potentially adding extra nutrients to the environment that can favour some plants over others and reduce biodiversity.

Trichomonosis is a parasite that mainly threatens finch species, and can be transmitted through fluids, such as saliva at feeders. During warmer months, the parasite can survive for longer, making the disease easier to spread.

The RSPB says that people can continue to feed birds with seeds and feeders during the winter months but it recommends they retire all bird tables and flat-surfaced feeders, with research confirming that there is a higher risk of disease spreading on flat surfaces, where contaminated food can collect. It is calling on people to clean and move their feeders weekly and, if they are providing water, to change it daily.

“The new advice is simple: feed safely and feed seasonally,” said a spokesperson. “During the warmer months from 1 May to 31 October, when disease can spread more easily, we are recommending people pause filling bird feeders with seed and peanuts to avoid large numbers of birds gathering in one place. Small amounts of mealworms or fat balls can still be offered safely throughout the year.”

The RSPB is also recommending bird-friendly garden planting, with sunflowers, teasels and ivy providing natural sources of seasonal food as well as encouraging insects, which are particularly important as a food source for many garden birds when they have chicks to feed.

In the Big Garden Birdwatch this year, the house sparrow once again held on to the top spot, with blue tit the second most-seen bird. The starling continued its revival, creeping up one place to number three. The wood pigeon and blackbird completed the top five.

Big Garden Birdwatch 2026 results: top 10

1. House sparrow – average of 3.57 per garden; seen in 57.1% of gardens; population fall of 64.3% since 1979.

2. Blue tit – 3.12 per garden; 78.5% of gardens; population rise of 28% since 1979.

3. Starling – 2.23 per garden; 31.4% of gardens; population fall of 85.1% since 1979.

4. Wood pigeon – 2.21 per garden; 75.2% of gardens; population rise of 1,003% since 1979.

5. Blackbird – 1.68 per garden; 71.7% of gardens; population fall of 58.1% since 1979.

6. Great tit – 1.58 per garden; 56.1% of gardens; population rise of 75.2% since 1979.

7. Robin – 1.50 per garden; 83.1% of gardens; population fall of 25.2% since 1979.

8. Goldfinch – 1.38 per garden; 27% of gardens; no long-term trend data.

9. Magpie – 1.32 per garden; 58% of gardens; population rise of 228.8% since 1979.

10. Long-tailed tit – 1.19 per garden; 26.2% of gardens; no long-term trend data.