In freezing conditions, birds need fresh water but if the can’t get it, they will eat snow, like this Great Spotted Woodpecker I have been watching in the garden. This Mistle Thrush, during a blizzard, managed to stand ankle deep in melting ice on the pond, and sip water from a more melted spot!
If you can, put out water for them. Conditions: Still, grey with early snow showers. Temperature: Max 1 Min -1C.