Researchers studying long-term changes In regional mouse populations have found that by focusing on the populations of a rare but widespread and easily identifiable species of mouse (Species X), they can make fairly accurate estimations about the total regional mouse populations.

In a report on a recent study that Included the data tables that follow, the researchers provided some addenda:

1. "The Species X population of Region CV increased by 123,995 between 1990 and 2005.

2. In contrast, the Species X population of Region EW declined by about 52% during that same time.