Migrating aliens

I found out about this tid-bit on the Wiki. I didn't see it posted anywhere. If it was, I apologize.

If you hover over a section of road in your town, the little aliens will begin migrating towards your location. It makes them easier to collect. The gremi-aliens also seem to run by your location more often as well. If you think you may have missed any, just turn off your buildings and decos to find them.