Alberta still has native 'pack rats' which could perhaps be mistaken for 'true rats' (the sort Alberta is ostensibly free of.) They are still actively fighting

Alberta still has native 'pack rats' which could perhaps be mistaken for 'true rats' (the sort Alberta is ostensibly free of.) They are still actively fighting them, it's a constant battle I suppose, but at least in theory there aren't any permanent breeding populations of true rats in Alberta. You're not even allowed to own a pet rat there.