The conversion of land adjacent to the Canadian Rockies into agriculture use and partial clear-cutting of coniferous trees (resulting in widespread deciduous vegetation) has been favorable to the white-tailed deer and has pushed its distribution to as far north as Yukon. Populations of deer around the Great Lakes have also expanded their range northwards, due to conversion of land to agricultural uses favoring more deciduous vegetation, and local caribou and moose populations declining. The westernmost population of the species, known as the Columbian white-tailed deer, once was widespread in the mixed forests along the Willamette and Cowlitz River valleys of western Oregon and southwestern Washington, but today its numbers have been considerably reduced, and it is classified as near-threatened. This population is separated from other white-tailed deer populations.