Thanks, Knowsnothing. Also, I wanted to add a few more things to this thread.
I was thinking about birds of prey such as hawks and eagles and found this question on Yahoo! Answers:
Do hawks eat meat and plants?
Best Answer (emphasis mine)
just meat. hawks don't take a nose dive to swoop up seeds lol. by evolutionary standards, they would just walk up to the plant and eat it (they're not going anywhere), then their elite flyings skills would be a waste.they'd probably end up evolving to slower creatures unless they are hunted like mad by other fast predators. plus their beak structures would also evolve to accomodate this diet range.