The trouble is, rattus norvegicus is not too fussy about its environment.
From the scienceblogs.com
A neighborhood needs everyone working to make the environment inhospitable for rattus norvegicus, but that's easier said than done.
From the scienceblogs.com
Rattus norvegicus, mistakenly classified in 1769 as an emigrant from Norway rather than its native Asia, turns out to have 2.75 billion pairs of DNA bases.
From the newscientist.com
When inspectors observed ARS or conditions favorable to rattus norvegicus, the property owner was promptly sent a notice detailing the findings and ways to correct the problem.