Well, as you can see, this one does!
I was visiting with my parents earlier today when my dad said he wanted to show me something outside. So we took a short walk behind his house toward a small farm pond. A few yards beyond the pond was a sweet gum tree with a large hollow in the bottom of it. Beginning about 25 inches from the ground, the hollow stretched up vertically about three feet high. As we carefully approached the tree I noticed a mallard hen sitting on her nest. She blended so well in the tree that it took me a few seconds to get a fix on her.
I have heard of mallards nesting in rotten tree stumps, but not in a tree itself. She seemed to me safer and more protected from the elements than she would have been on the ground. It's like she knew exactly what she was doing.
She has been setting on 9 eggs for about a week now. I hope to have the opportunity to provide more updates on her success.
Notice how well she blends in...