I am want to plant a small tree in my backyard. I live in zone 6a and want to plant something beneficial to wildlife in my area that gets no bigger than 15-20ft tall. My yard is very wet so something that can soak up lots of water. My soil has lots of clay. Any suggestions would be appreciated.

I am very happy with how Fringe Tree (Chionanthus virginicus) has done in my yard. We have lots of clay, and while I don't know that it 'soaks up' water, we have one growing happily in a spot that gets standing water for a few months in the spring, so it at least tolerates it. It has unique flowers, and the leaves are consistently attractive, even when other things start looking shabby in the summer. Unfortunately, you have to plant a male and a female to get fruit set, which the birds would like best and I didn't luck into that, but am still very happy with it. They are a bit hard to find sources for, which I don't understand, I think they should be much more widely planted.

I think the butterfly forum ( https://garden.org/forums/view... ) has links in their sidebar listing plants that are hosts for specific butterflies and birds.

Edit: The Amelanchier family is also very nice for wildlife. Early nectar and fruit for birds. I forget how they do in wet soil though.