Animals will approach cages on their own rarely, but if you put food they like inside it (with a stockpile), they will be attracted to them. As for their pathing and movement, they pick spots around the map (which they can reach) at random, so it's possible they could show up and just stick in one area, or they could zip across the map. It's best to litter the cages around the map to cover more area, but putting food inside the cage will help them move towards them.