I got a few of those last year.. one along with a couple mallards on the same hunt. Packaged them together.. cut the breast into strips, battered and fried them and I literally could not tell which was mallard or whistler.
They are good to eat but kinda a pain to clean. The skin is tough like a diver or at least that's what I remember. We used to winter a ton in our reservoir because we had a lot of water hyacinth and they would roost on top of it. Since the storm surge of Hurricane Ike in 2008 killed all of the hyacinth we have not killed one tree duck in our reservoir. They are mostly gone by the time duck season rolls around nowadays.
Loc: My favorite place TEXAS
I've always liked watching them, cool little ducks. Had them coming to a deer feeder once that was well over a mile from the nearest water. You could set your watch by them, always there right before the feeder went off.