The poisons of some fruits including berries is sometimes contained in the
seeds which pass harmlessly through birds. Indeed, some seeds found in
berries germinate best after being "processed" by birds. Madrones are that
way. I'm not an expert on nightshade but this could be the case. I've heard
of some mild to severe reactions from humans eating the berries but it's all
hearsay. So, if you see a vine-like plant with leaves that resemble a
tomato, you will want to leave the berries. They're for the birds.
Steve Ellis
sellis at coup.wednet.edu