Study: NYC Rats Have Evolved Into 'Uptown,' 'Downtown' Breeds

NEW YORK (CBSNewYork) - New York is a city of diverse humans, and a Fordham University grad student team has discovered it may be a city of diverse rats as well.

A study by five researchers found Manhattan's "uptown" and "downtown" rats are genetically different, as are "West Village" versus "East Village" rats.

A sampling of 262 Rattus norvegicus -- or brown rat, to laymen -- were used to find out where the original rats of New York City first came from and how various neighborhood's rat populations were related to each other over time.

"Across Manhattan, rats exhibited a homogeneous population origin from rats that likely invaded from Great Britain," the researchers said.

Since the move over from Europe, colonies of rats became more tightly clustered to groups staying within a few blocks of a common nest or area.

In addition to trapping and measuring the genetic profile of rats, the team also used a crowdsourced online "rat map" showing a concentration of rats below 34th Street and another group on the Upper West Side north into Washington Heights.

Between the two groups, Midtown appears to have less to offer rat colonies as bases of residence.

In the city's most recent attempt to win the war against the furry vermin, Mayor Bill De Blasio announced in July a $32 million plan to reduce the rat population by 70 percent. Since then in Manhattan, parents have complained that rats have taken over parks in the Upper West Side, with some residents saying the animals have attempted to jump into their children's strollers.