https://phys.org/news/2018-06-york-rats-ice.html

Rick Simeone's team is at work in Sara D. Roosevelt Park on the Lower East Side, one of Manhattan's oldest districts.

The day before, they spent more than three hours locating all the entrances to the burrows, 67 in all. That means there could be more than 250 "rattus norvegicus," the scientific name for common brown rats, living there.