New York rats: Did they sink or swim?

2012-11-01 12:12

New York - As Hurricane Sandy pushed floodwater through New York's streets and into its subways, many wondered how the city's infamous rat population would fare - sink or swim?

For some, the deluge that accompanied Sandy raised fears of a "ratpocalypse", with the city's least glamorous 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 rodents.

"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 said.

Unsavoury elements

"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 re-establish 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 said in an e-mail.

Still, those that did make it overground would be feasting.

"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," Zikovic said.

Despite the abundant food available to them, life won't just be a walk in the park for the new overground arrivals.

"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," Zivkovic said.


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," Zivkovic said.

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 said, 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.

Robert Corrigan, a rodent specialist based in Indiana, noted that in previous major storms, including Hurricane Katrina of 2005, "massive disease outbreaks did not occur".

"No reason to assume they will occur with Sandy. But that doesn't mean city health officials can, or will, let their guard down," said Corrigan.

  • fidel.mgoqi - 2012-11-01 12:25

    The rats would have moved prior to the storm hitting the mainland. Most animals have exceptional senses that fore warn them of impending natural disaster.

      thabang.makgoka - 2012-11-01 13:01

      Intresting fact!

      ludlowdj - 2012-11-01 14:30

      Spot on, buy the time the storm hit the rats would have been far inland and out of harms way. this phenomenon although rarely seen in the modern age is where the term "like rats abandoning a sinking ship" originated from.

      Cayowin - 2012-11-01 15:54

      Then why the heck is my Labrador still totally surprised by raindrops? He runs round in loops trying to bite them as they hit the ground.

  • kenpeg.dawson - 2012-11-01 15:27

    I never gave that one a thought more worried about the people. Makes you think about the stray cats and dogs as well. Maybe the fish that were washed into the system ate the rats that fed the cats that were chased by the dogs that lived in the house Jack built.

      rowan.clark.10 - 2012-11-01 18:38

      Now I still don't know if Sandy was a rat trap or a side walk ratatouille Now I have to google ratatouille mmm looks good !.

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