Rabbits and foxes have disappeared, while raccoon, opossum and bobcat populations have dropped as much as 99%, researchers at Virginia Tech University, Davidson College and the U.S. Geological Survey reported in 2012.

CNN: STORY HIGHLIGHTS

The largest single school shooting in U.S. history, which occurred at Virginia Tech in 2007, was perpetrated by Seung-Hui Cho.

CNN: Rejection, bullying are risk factors among shooters

Virginia Tech has been, statistically, one of the safest campuses in the U.S. The school of over 27, 000 students reported just 45 crimes in 2005 to the Office of Post Secondary Education, a rate of 1.6 per thousand.

FORBES: Keeping Campus Crime At Bay

The mass shooting is the worst in the U.S. since a gunman killed 32 people and then took his own life in 2007 at Virginia Tech.

WSJ: 12 Killed in Colorado Theater Shooting