Rats like the built-up environment and being near people and their waste, the study and outside scientists said. They essentially eat at the same table as humans, multiple experts said.

Each litter is eight to 16 baby rats, Richardson said: “That is a recipe for accelerated population growth. ... “The rat is the third most successful mammal behind humans and house mice.

Each litter is eight to 16 baby rats, Richardson said: “That is a recipe for accelerated population growth. ... “The rat is the third most successful mammal behind humans and house mice.

Washington was by far the leader in rat increases, followed by San Francisco, Toronto, New York City and Amsterdam.

More rats infesting cities as scientists say warmer temperatures mean ... Each litter is eight to 16 baby rats, ... “The rat is the third most successful mammal behind humans and house mice.

Rats like the built-up environment and being near people and their waste, the study and outside scientists said. They essentially eat at the same table as humans, multiple experts said.

WASHINGTON (AP) — Rat infestation in many world cities appears to be soaring, especially in Washington, and a new study blames warming temperatures, urbanization and other human actions.

Each litter is eight to 16 baby rats, Richardson said: “That is a recipe for accelerated population growth. ... “The rat is the third most successful mammal behind humans and house mice.

An extra month may not sound like much, but female rats can have a litter every month. Each litter is eight to 16 baby rats, Richardson said: “That is a recipe for accelerated population growth.” ...

An extra month may not sound like much, but female rats can have a litter every month. Each litter is eight to 16 baby rats, Richardson said: “That is a recipe for accelerated population growth.” ...

Each litter is eight to 16 baby rats, Richardson said: “That is a recipe for accelerated population growth. ... “The rat is the third most successful mammal behind humans and house mice.