He looks like a Carolina Wren to me, but I'm hoping for a Marsh Wren. He was pretty small. Carolinas are pretty big as far as wrens go.
I was shooting in the Missouri Botanical Gardens today. He was poking around in the lily pond as I was composing a building. He was so accustomed to people, he was never more than 10 feet away from me and acting as though I wasn't there. He was there so long he allowed me to switch lenses and really try and line some shots up. I came away with about 5.



