Bobby Corrigan’s Thoughts on Sandy’s Impact on NYC’s Rats

Editor’s note: As New York City continues rebuilding from the destruction caused by Hurricane Sandy, a question among many pest management professionals is: “What will happen to the rodents?” Dr. Bobby Corrigan, of RMC Pest Management Consulting and a PCT columnist, was interviewed by EPA about the impact of Sandy’s flooding as well as any other type of ground-flooding.

While much of the public’s focus is on New York City’s subway system, Corrigan said rodents are not necessarily the worst in the subways, “In modern day cities, like New York and others, rats are opportunists in their use of city. They will move into protective harborages that are not just exclusive to subways. Others include sewers, sub-street defunct pipes, parks, basements and in some areas, where trash is abundant, even below the every-day sidewalk cavities that people walk upon daily.” Corrigan added that each urban neighborhood can have a different "rat profile,” which depends on a range of complex physical and environmental factors that dynamically interact.

EPA: Is it true that flooding in the subway system could cause rats to relocate into occupied buildings?
Corrigan: Baby rats not yet ambulatory perish for sure if their nests become submerged. Some flushed rats will swim for their lives and survive. Among the better swimmers who do survive and make it to ‘dry ground,’ some of these may still not be able to find suitable shelter and easily accessible food quickly enough and will perish from displacement stress, or other calamities. But yes, it is probable that some rats will be successful in riding the storm out and in adapting to new places if there is also the resources they need (e.g., garbage). It’s case by case; block by block.

EPA: Can we expect an outbreak in diseases carried by relocated rats?

Related: MTA Efforts Corrigan said New York’s Metropolitan Transportation Authority (MTA), during the past three years, has been addressing rat issues more aggressively. “They are concurrently conducting several pilot studies on how to best minimize rodent infestations and rodent sightings within their system of 465 subway stations; the majority of which have no rats issues whatsoever. I believe the City of New York will see these efforts pay off beginning with the next several months and for the immediate future.” — Brad Harbison

Corrigan: The epidemiology of pathogens…their reservoirs, vectors and transmission… is far beyond rats being flushed out of their hiding places from storms and hurricanes. If disease pathogens are not prevalent prior to a surging storm, they are not likely to suddenly increase in a massive outbreak in a modern city. The potential might be greater in a third world country city perhaps. But here, as with other major hurricanes and floods (Irene, Katrina, etc), rodent-borne disease outbreaks did not occur. So there is no reason to assume they will occur with Sandy. But that doesn't mean city health officials in any city can or will let their guard down. It will take weeks for the effects of Hurricane Sandy on the rat population to become apparent. Similar to Katrina, there has not been any immediate increase in rat complaints inside apartments and other occupied structures.

Corrigan’s initial impression is that Sandy has negatively impacted many of the subterranean populations of rats that could not get to higher ground quickly enough. “Each day forward might bring different news, but as of October 31st, there have not been ‘hoards of rats’ displaced to the streets and running about as some are worrying about.”

WHAT’S NEXT? EPA added that the information relayed by Corrigan supports the assertion that while there may be some displaced rats looking for a new home, it is unlikely that a significant overall increase in rat infestations will occur as a direct result of the Sandy. For a short period of time, displaced rats may be seen in areas they did not previously inhabit. Alternatively, some established rat colonies may vanish entirely.

Related link: www.epa.gov/opp00001/controlling/rodents.htm