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According to the RSPCA, there are only two species of rats living in the UK - brown rats and black rats.

Although most historical accounts date the arrival of brown rats to about 1775, new evidence suggests this ratty rivalry began much earlier.

Today, both types of rats exist in North American cities, though brown rats are more prevalent.

The past decade has seen a boom in descriptions of unexpected pollinators, including lizards, opossums, brown rats and cockroaches.

New York City’s common brown rats share the same traits, but their shorter lifespan makes them unlikely candidates for such trainings, Szott said.