This is when the birds really need you! A diversity of foods will allow you to help a diversity of species. High calorie foods like fatballs, suet blocks, peanuts and sunflower seeds are all great. Put the food in multiple locations – in different feeders, but also some on the ground (or roof or on top of a wall to keep away from cats/rats) for species that don’t like hanging from feeders.
One of the most important things during cold weather is to put out fresh water. The icy conditions mean natural water sources might be frozen over, so your birds will need somewhere to drink and wash themselves. Keep an eye throughout the day to make sure the water you put out hasn’t frozen over and top it up with fresh water each day.