I'll see if I can find the link again, but there's a very extensive article (actually, almost book-length) that is a compendium of all of the research on the benefits and negatives of supplemental feeding. And in certain circumstances there are benefits, especially in areas with very limited quality or quantity of resources year-round or just seasonally. But the negatives of supplemental feeding documented in scientific studies are numerous, with many being very subtle. Providing a concentrated spot for predators to hunt their prey is one of those subtle negatives. So is the concentration of wildlife around the feeders. Not only does this increase the risk of communicable disease transmission, wildlife concentrating on a feeder site eat far more than just the food in the feeder. They end up devastating the habitat near the feeders. I've seen this with my own eyes. While touring a new clients property, I can often tell when we are getting close to a feeder because of the concentrated excessive browse pressure.