In addition to taking out their predators, we have also fragmented ecosystems.

Certain species like deer thrive in the boundaries between two different ecosystem types because they get different resources from both ecosystems.

Humans do not only reduce forest size, but also change the geometry of forests: fragmentation makes the edges more pronounced (increases the perimeter:area ratio)

This harms some animals like large solitary predators who require vast ranges, but helps other species like deer who prefer the edges.