I've been hearing lots of bird songs lately. We have wrens and mockingbirds which are quite noisy. The last two days I've been hearing a catbird in the backyard. The catbird mimics the sounds of other birds like the mockingbird does.
A cute experiment is to get a three or four-year-old kid and have him mimic the mockingbird. It can be quite entertaining.
Once the UPS guy delivered a package and set it on the deck of my neighbor's house. He set it down in front of a motion-detecting frog which began croaking. (I'm guessing it ran the battery down considerably.) By the end of the day, I noticed that the mocking bird was mimicking the sound of the frog.
In a recent email I received, the Cornell Lab of Ornithology introduced a new game which helps a birder identify bird songs in a visual way. A spectogram of the bird song is matched to the bird. I found this very interesting; it used a part of my brain that I don't use a lot.
The game is named Bird Song Hero. (The name is similar to the popular Guitar Hero in which a gamer tries to match a recorded musical phrase with his own guitar playing.)
I think this link is worth a look (and a listen)!