Where have all the birdies gone?

I've noticed over the past couple of days that I've been home that the wild birds have all but disappeared from my garden.  I know they would have come around before I left because I fed them (heaps!).  I never expected my house-sitter to feed them so they've had to look elsewhere whilst I've been away so I'm putting out plenty of food now in the hope of enticing them back.  One or two have visited but nowhere near the number I was getting before.  I'm confident they will return very soon though..........