Snow and the Birds.

It’s snowing again – has been for the last five hours, and I’m getting a bit fed up with it. However, the question I have is this:

Every time the ground is covered with snow, the birds go frantic for the food I put out. I assume that’s because their usual source of food – seeds, insects, grubs, worms and so on – is cut off. In that case, how do they manage when there isn’t a human providing an alternative? I remember one winter when there was quite deep snow on the fields and gardens, and even the side roads, for eight weeks without a break. How on earth did any bird survive? I want to know.