Rats in Canada

I found a rat with no hair on its tail, body colour was Grey, in my house a few years ago an just read how we only have the Bushy tailed rats and the one I found was about 16 Inches in body length, lower jaw teeth about 3/4 inch long and the tail was about 9 Inches, could this be from rising temperature over years causing them to come up to a more Northern country.  Stanley,  Ottawa.

You have described what is probably a Norway Rat. They arrived in North America with the first ships from Europe that touched our shores.  They are common in all areas where there are humans, unintentionally feeding them. Their migration has nothing to do with climate change although the reproduction and survival rate could be affected in colder climates. Read more about rodents.  http://pestcontrolcanada.com/how-to-get-rid-of-rodents