Humans modify natural landscapes in a variety of ways, from constructing expansive cityscapes to fencing off otherwise untouched rangeland. A new study, co-authored by biologists at the University of Maryland, describes the extent to which highly modified landscapes impede the movement of 57 land-based mammal species from around the world. On average, these mammals cover about a third to half of the distance they would otherwise travel in wild, unmodified landscapes.