How Fickle are the Birds

With the recent cold weather, the cold frosty mornings, the days when the temperature failed to climb above the point of freezing, the garden was alive with birds. Great Tits, Blue Tits, Coal Tits, Robin, Wren, etcetera, etcetera, you get the picture. At the weekend the weather changed and the frost and the ice disappeared. So to it seems did the birds, they did a vanishing act.
Yesterday, although I admit that I did not spend much time in a position where I had a view of the garden, I did not see a single bird. They were in fact conspicuous by their absence. The food put out in the morning was still untouched as the afternoon turned dark.
How Fickle are the birds.