America's rats are being hit hard by the coronavirus. As millions of Americans shelter indoors to combat the deadly virus, which has claimed over 21,000 U.S. lives, many businesses — including restaurants and grocery stores — have closed or limited operations, cutting off many rodents' main sources for food. On deserted streets across the country, rats are in dire survival mode, experts tell NBC News.

"If you take rats that have been established in the area or somebody's property and they're doing well, the reason they're doing well is because they're eating well," Bobby Corrigan, an urban rodentologist, told NBC News. "Ever since coronavirus broke out, not a single thing has changed with them, because someone's doing their trash exactly the same in their yard as they've always done it — poorly."

But many other rats are not faring as well, said Corrigan, who works as a consultant for several city health departments and businesses, such as airports and shopping malls.

"A restaurant all of a sudden closes now, which has happened by the thousands in not just New York City but coast to coast and around the world, and those rats that were living by that restaurant, some place nearby, and perhaps for decades having generations of rats that depended on that restaurant food, well, life is no longer working for them, and they only have a couple of choices."

And those choices are grim. They include cannibalism, rat battles and infanticide.

Read the full story at NBC News.com.