Hope I'm not too late with commenting, but I've found that some types of shadow people follow people around. Their population consistency can change based on an influx of people. The shadow people that feed off of energy and get denser in population when there are a lot of people gathered/gathering (cities, events, busy crossroads, etc.), will move from one location to another if that means they can get their fill. While there are shadow people that seem to move independently of whether or not humans are around, when a big event is going on, it is possible to witness "herds" of shadow people moving towards the gathering. For this, they can easily cross large fields and forests. 

To me, it seems that the shadow people further away from dense parts of civilization, are more of a "take your time, enjoy the view" mindset, rather than having to be focused on one goal or another. The ones I've seen in forests and other quiet areas, seem calmer, move slower, and appear to radiate a different energy - they lack the cold, draining absence of it, in general.

When they get into densely populated areas, it seems often times out of a desire for energy or curiosity. The ones that like the quiet, seem less interested in our daily lives and will not go into homes as eagerly, though they can get curious when you get to "their home".