I don't believe its encouraged as it can cause some troubles, and in general its better for them to wander as they need to to find food sources. Corn can be bad for a couple reasons, first off I wouldn't want to try convincing D.E.C. that you are not feeding deer, and second depending on the source the corn come have toxin (anafloxcin or something like that) that can be harmful to birds. Maybe if theres an extended time of deep soft snow that they can't get around in very well, they could benefit from something like black oil sunflower seeds. I still wouldn't do it very often asit could get exspensive and if they stay concentrated in one area, predaters will find them