Who's That Rap-rap-rapping at My Window?

I heard a clicking sound coming from the kitchen, almost like very large rain drops directly hitting the window... except that it's sunny outside. So i walked slowly into the kitchen and glanced over - there is a small, rather non-descript bird (can you tell what it is from the picture?) tapping on our window. Is he trying to get in? Is he tapping something in Morse code and i'm missing it all? He's been at it now, as i type, for nearly 10 min. I'll have to ask Ron if our lil' visitor was here earlier.