I've always enjoyed watching birds at our feeders around the house and the few I can spot while out on walks.
But I seldom get a good enough look to be able to identify too many of them. The books will tell you to notice features such as a ring around the eye, a white bar on the wings or some other detail that I'm rarely able to see. Far too often, the lighting isn't right or the bird is hidden behind a branch so these visual clues aren't that helpful. But I am able to hear many different types of birds, most of which I can't see at all.
So I've tried listening to bird songs on tape to try to figure out who it is I'm hearing. All those songs, one after the other, however, quickly become a blur. That was, until I was introduced to "Birding By Ear," a CD set put out by the Peterson Field Guide Series by Richard Walton and Robert Lawson. This recording takes a completely different approach from other bird song recordings I've tried. Walton and Lawson take 85 birds from eastern and central North America and sort them into learning groups of just four to eight species. They then contrast and compare these few birds, giving listeners tricks on how to identify each one.
Once they explain the particular clue to listen for, they go back and forth between a couple of birds so you have several chances to practice what you've learned. For example, the downy woodpecker has a downward chatter, while the hairy woodpecker has a similar chatter but it stays at a more steady pitch. If you heard either one alone it would be hard to tell them apart at first. But once you've heard them compared one after the other a few times, it's relatively easy to hear the difference.