Photos: Smithsonian Contest-Natural World

There's a photography contest that Smithsonian Magazine is putting on, and I'm planning to enter. Here are the six photos I'm currently considering for the Natural World category. Alas, I can only pick one per category. (Click for big versions).

Forest Glyph	Killdeer
Clouds over the Beltline	Paused Squirrel
On a Big Sidewalk	King's Clothes

Any input welcome.