Why have coyotes spread out to live in more areas of Canada?

The coyote is native to North America. Despite being extensively hunted, the coyote is one of the few medium-to-large-sized animals that has enlarged its range since human encroachment began. It originally ranged primarily in the western half of North America, but it has adapted readily to the changes caused by human presence and, since the early 19th century, has been steadily and dramatically extending its range. Sightings now commonly occur in a majority of the United States and Canada. Coyotes inhabit nearly every contiguous U.S. state and Alaska. Coyotes have moved into most of the areas of North America formerly occupied by Gray_Wolf, and are often observed foraging in suburban garbage bins.

Read more about coyotes in Wikipedia.