In reply to kathrync:
Starlings are excellent mimics and I've heard a tame one immitate words too!. Their mimicry can even tell you where they've been too before. I worked in the Shetland's some years ago and a starling was 'singing' above my head. Then I heard the distinct 'meow' of a buzzard and instinctively looked up. Of course there was no buzzard as they did not occur on Shetland. But it did tell me that the starling I was listening too had lived in a location where buzzards were common.
I believe there are bird song apps, but I've never used one. Identification of birds by their calls and songs is a method almost all twitchers, birders etc., use. And it has its manay advantages over trying to identify a bird by sight. As Mick Taylor mentions, walking anywhere and you can ID a bird as long as you can hear it and you don't have to spend time looking for a bird - as you have found out.
Writing this reminds of many years ago I lived for a couple of years in a city. Walking home one evening I heard flying above me the wild cries from a flock of Redshanks flying in the dark, above all the noise and traffic. With the current reduction in traffic noise I'd guess its easier to hear bird sounds in towns and cities now.
Post edited at 07:56