BIRD-SONG is one of the most charming mysteries in nature; it has no counterpart in art. I have at times fancied there was some analogy between it and the art of poetry, but there is none, in fact.

The birds were singing something strange. Ken Otter and Scott Ramsay first noticed it in the early 2000s, when they were recording white-throated sparrows in Prince George, a city in western Canada.

Mornings these days resound with bird song, and it's a cheerful start to my day. The crimson-plumed male northern cardinal is one of the first songsters at the break of day. He sits atop a bush in my ...