How often should I clean my bird feeder?

Mouldy seeds or fatballs can spread disease, warn experts — and smaller birdfeeders are often easier to clean

The disease that has had the largest impact is trichomonosis. This affects birds by swelling their throats, making it difficult for them to swallow. They then cough up seeds, which are picked up by different birds, spreading the disease

As the cold weather continues, wildlife lovers are filling up their feeders with seeds, nuts and other goodies to attract as many birds as they can to their gardens.

But if the birds are slow to polish off the treats, how long will your bird food keep when exposed to the elements?