Yesterday I got my first ever chance to photograph a grasshopper warbler. These are generally shy birds that are often heard but rarely seen. The characteristic sound is a very long rattle, almost like a rattle snake. I heard this one long before I got a chance to see it. This was an unusually tame bird, I got the chance to take 40 pics at a comfortable distance. Light wasn't from the best direction but this way it does work I think. While I was observing it I was stunned at how long such a tiny bird can make so much noise.
Here's the sound one of these makes:courtesy of wikimedia