Rodents in general need to work down their teeth and this is often done on materials harder than their teeth. Every once in awhile I’ll notice some wiring on pool equipment that looks like it has been chewed on. This last month in Paris, France this habit took on dangerous overtones when a train accident occurred. Rats nibbled on signalling cables and this prevented a light to function correctly. “Rats blamed for rail accident“, luckily no one was killed but 40 people were injured.