Title should be changed to reindeer, not deer. As those are domesticated by the Sami people. Then it makes more sense and should not be a major task, since they are regularly caught to be ear-marked for example. In general a good idea IMO.

For deer it would be trickier, but I imagine you could somehow do it by setting up feeding stations (pretty common with hunters) and spray them when they approach it. But it would be messy. Now my imagination is wandering, please stop me.