Exactly...
A LOT will depend on if what you offer will be better than what they can find to call home. Distance from the mother hive "can" also make a difference... We have all heard of a swarm moving into the empty hive next door, so I think persoanlly, that it depends on availability of new homes they can find.
Dr. Seely did a test to see how accurate they are at finding the best location, and set up several different sized boxes on an island with no trees... the first place they picked was a chimney of one of the few houses on the island... they had to seal up the chimney, then the bees began investigating the ground level boxes he had set out.
So, if you have hollow trees, barns, houses etc.. especially if they have an old hive in them your feral bees may select one of those sites before yours...
The best thing to do is try to make sure your box is the best spot. Make sure it is large enough, has old comb in it if you have any, and get some Swarm Commander from Scott's site...
All you can do is try to shift the odds in your favor... like Fishing.. you pick the spots to fish you think will be most productive and give it a go!
