Nobody will notice if that tree is missing, and I do agree it is a little distracting, at least where it's placed right now... It's in no way meant to be the focus of the painting, I'm sure, and you have an artistic license to carry a brush and make the changes you deem necessary!
I also miss something colorful at the birdhouse, since I follow his gaze. It's not a type of thing that would attract a hummingbird, they would have been down in the flowers, I'd go for a cardinal or bluebird. (Can you tell I'm an official Backyard Bird Counter?