We all know how well coyotes adapt to changes in there habitat, or new habitats. As to increasing sizes the northeast IMHO does have coyotes with wolf genes running rampant in their systems. The coyotes in the south, and to some degree here in WA. at least some of the time have gained weight and size by breeding with dogs. There was a "coyote" near where I lived close to Poulsbo that had legs like a basset hound but coloration of a coyote. In the deep south you can shoot songdogs with all colors of coats, not just shades or tints but real color, red, black, white, brown, grey. I can only believe that is from mating with dogs.