we used to call it birdwatching, but so much of what we do relies not on what we are seeing but on what we are hearing. Nevertheless, the sheer volume of what bird sound could be telling us is underestimated by almost every birder. Mark and his co-authors have made great strides teaching us how to listen, be aware and become better birders. While I still prefer paper books (and the hardcover is beautiful), there is a great charm in having the accompanying sound files available at a click and the format lends itself really well to understanding the message.