For some, the deluge that accompanied Sandy raised fears of a “ratpocalypse,” with the city’s least glamourous residents crawling in their thousands up out of their subterranean habitats and into the streets.
Others pondered the possibility of a grim “rat soup,” imagining dozens of the rodents drowned and floating along on the tide of water that swept into the city’s subway stations.
No one knows just how many rats there are in the city, with experts at odds over the accuracy of one common estimate suggesting there is at least one rat for each of New York City’s eight million human residents.
And Rick Ostfeld, a disease ecologist at the Cary Institute of Ecosystem Studies, said it was similarly difficult to predict what had happened to the rats.
“Rats tend to inhabit very low lying areas that are most subject to this intense flooding. So some rats will be killed, they’ll be drowned in the water,” he told AFP.
“But I would expect that relatively few will be killed by a flood of this nature, because as quickly as the floods can rise, the rats can rise. They can swim quite proficiently and climb and get up and out of harm’s way.”
While a rare fan of the rat, at least as a research subject, Ostfeld pointed out that the rodents can carry a slew of unsavoury ailments, including leptospirosis and salmonella.
Those rats that make it up to the surface “could pose a threat to us in new parts of the city where they haven’t been,” he warned.
In the short term, Ostfeld predicted, survivor rats will be looking for new homes, trying to get by in a new environment and reestablish a social order.
“But once these new social structures are maintained, are formed, I would expect the rats to begin breeding again,” he said.
“And if there’s a massive amount of new food as a result of the storm… that could constitute a new food resource for rats and we could see a population increase.”
But Bora Zivkovic, a behavioral biologist and editor at Scientific American, predicted the storm might well have drowned a portion of the city’s rodent dwellers.
“Rats, especially the pups, in the areas most quickly flooded, or without good easy exits to the surface, would have drowned,” he told AFP by email.
Still, those that did make it to the surface would be feasting, he added.
“Much more food will be thrown away, at all hours of day and night, and I assume that trash pickup will be temporarily erratic, thus leaving plenty of food sitting in plastic bags on sidewalks for a while.”
Despite the abundant food available to them, life won’t just be a walk in the park for the new overground arrivals, he added.
“Displaced rats will interact with local rat groups, probably in quite aggressive encounters. Those encounters will decide who is dominant, who stays and who leaves.”
And for those terrified by the prospect of street corners overrun by aggressive rodents, he had calming words.
“Most rats would try to go back home once the water subsides. They are very loyal to their home territories and groups and can find their way home from quite far away.”
He added that while breeding would quickly bring the rat population back up to pre-storm size, there was “no reason to expect it will get bigger.”
Sam Miller, assistant commissioner for public affairs at New York City’s Health and Mental Hygiene department sounded a similarly optimistic note.
“We haven’t seen an increase in rats above ground caused by Hurricane Sandy,” he told AFP, echoing Zivkovic’s theory that the flooding could reduce the rodent population by drowning young rats in burrows.
“We believe the flooding could reduce the rat population overall,” he said.