but cats are threatened too.

Domestic cats an endangered species? Now, THAT has to be the most idiotic statement I've heard in many a year.

How many you want? Go to any animal shelter in the world- they are gassed in the thousands- perhaps millions- anually because they are vastly overpopulated. Same for dogs.

Didn't the Europeans forego their attempted annihilation of small felines and start encouraging their proliferation because of the bubonic plague being spread so wildly by rats and mice?

No, they did not. The link between yersinia pestis & the rat flea wasn't established until the very end of the 19th century.

Greg, if the wilde beasties higher on the food chain...

Ah, but then felix domesticus are NOT "wilde beasties", they're domestic animals, like cows, pigs & chickens. Just because some irresponsible human failed to get Moggie spayed or neutered & their progeny became "wilde", or allowed Moggie to run "wilde" or abandoned him/her doesn't create a "wilde beastie".

In some areas, feral cats are worse plague than rodents could ever be, and should be turned over to the same exterminator to deal with.

The REAL wilde beasties higher on the food chain- hawks, owls, weasels, stoats, etc. do a more than adequate job of keeping the wild rodent populations in check.

If one has a problem INDOORS with rattus rattus, rattus norvegicus or mus musculus Moggie needs to be indoors anyway to be effective.