When birds congregate together they are more likely to spread disease and as the weather warms up it can provide the ideal conditions for harmful bacteria which can exacerbate the potential problems. There are a few things you can do to keep your feeders and bird table clean, hygienic and therefore healthy.
1: Avoid putting out too much food. Much better to feed regularly that leaving too much food out which can go off and become bacteria breeding grounds.
2: Use birdfeeders and a bird table and therefore avoid feeding on the ground. This can attract rats and again they can carry disease which can spread to birds.
3: Move your birdfeeding station from time to time as this will help avoid the accumulation of bird droppings underneath which can cause problems.
4: Clean and wash your table and feeders regularly. It's a good idea to use a very diluted disinfectant solution.
5: Change the water in your water containers or bird baths regularly and again give them a good wash from time to time.
Don't forget your own health and hygiene - wash your hands after birdfeeding, avoid bringing your feeders into the house to clean and be especially careful if you handle a poorly bird.