This is an excellent question, one I ask myself all the time. If we humans are going to break the rules and feed wild animals, we certainly must take full responsibility for the repercussions. They say "Don't mess with Mother Nature," and we should keep this tenet in mind. These birds would be fine without us, so feeding them is like opening a can of worms (so to speak!) in that it might make them more dependent on humans (and less independent and able to help themselves, as a result.) If the food we feed them is harmful, we can hurt them that way, too. For example, what if the peanuts I buy from Costco are laced with some kind of pesticide I don't know about? Even if I don't know this, it's my responsibility if the birds get ill as a result of my actions! So it's great that you are asking yourself this question, since it means you are acting responsibly and you'll be less likely to hurt them as a result.