The Royal Society for the Protection of Birds said cleaning should take place every week or every time feeders are replenished. It comes after a YouGov survey found that only half of people using bird tables and a third of those using feeders clean them fortnightly.
The charity said if people can’t “clean weekly” then they should find other alternatives such as “putting up nest boxes, planting native vegetation or leaving messy corners of the garden for nature.”
Chief executive of the RSPB, Beccy Speight said: “We know that, for many people, garden birds provide an important connection to the wider natural world and bring enormous joy.
“Over the last year, there has been a broad and much-needed realisation that nature is an important and necessary part of our lives, especially for our mental health and well-being.
“But nature needs us too and we want to help make sure that people are providing the best offering they can for birds at a time when many species are in decline.”
The charity is hoping that the launch of the Big Garden Birdwatch, thought to be the world’s largest garden wildlife survey, will encourage people to attract different species to their gardens.
The survey, which has been running for 43 years, kicked off on Friday and will run until Sunday, January 30 asking the thousands of participants to spend an hour watching birds in their garden, balcony or local park and record how many species visit.
Last year’s survey, where over a million people took part, revealed House Sparrow, Blue Tit and Starling as the top three most seen species.
But some past surveys suggest the most common birds seen in gardens have called since 1970, such as house sparrows, blackbirds and robins.
The warning from the charity comes as bird flu was recently found in several parks in Birmingham as people were warned not to touch sick of dead birds by the UK Health Security Agency.
Authorities said they were working with the Animal and Plant Health Agency and the RSPCA ‘to manage the situation and protect public health and the risk to other birds, wildlife and pets’.
Bird flu is known to spread easily among wild birds and poultry and can infect humans.
It is usually spread by contact with infected animals and symptoms can range from mild-cold-like symptoms to more severe cases such as pneumonia and death.
Angela Cartwright, consultant in Communicable Disease Control with the UKHSA in the West Midlands, said: “The risk to the public from this strain of avian flu is very low.
“This is an infectious virus which spreads among birds and it is very unusual for humans to be affected.
“However, it is possible for humans to catch the virus through close contact with an infected bird, dead or alive.”