Also, because rats live in a world of smell, their former homes might have been rendered unfamiliar by a flood, he said, even if the buildings, parks or tunnels they had been living in suffered little permanent damage.
"To a rat, it wouldn't look the same, it wouldn't smell the same," he said.
Jessica Lappin, the councilwoman who proposed the emergency extermination program for flood-damaged neighborhoods, said she was skeptical when she first started hearing stories about rat infestations since the storm but has come to believe the problem is real.
"We are used to seeing rats. But it definitely seemed to be getting worse," Lappin said.
She noted that even though the health department's citywide rat complaint numbers show no increase, there has been a rise in select Manhattan neighborhoods near where flooding occurred.
Those neighborhoods include the West Village, where mice first turned up in a basement storage area at Magnolia Bakery in the weeks after the storm, company spokeswoman Sara Gramling said Thursday. The bakery was cited by city health inspectors in January, then was closed down Feb. 14 after a follow-up inspection. It reopened two days later, with lines even longer than usual.
Gramling said she was sure the storm was a factor in the infestation, although she noted that there is also a large construction project taking place down the block.
"At the building, and in the West Village, there has been an influx across the board," she said. "We don't feel like it's an isolated incident. Clearly there is a trend."
Thomas King, a manager at M&M Pest Control, an extermination business based in Chinatown, said his company's rat calls are up 20 percent to 30 percent since the storm.
Recent media coverage of the supposed rat scamper caused by Sandy has focused on Brooklyn Heights, a historic district perched on a hill above the East River. But the neighborhood's rat problem is hardly new. Nearly every year has brought a new newspaper story about rats in the neighborhood, usually linked to trash left by visitors to the Brooklyn Promenade, the neighborhood's elevated esplanade.
The Brooklyn Heights Association, a civic group, did get some reports after the storm about new rat burrows being dug in gardens along the Promenade, but city park officials took quick action, and there have not been any complaints since.
So the mystery remains.
At least one notable rat population perished for sure: 7,000 lab rats and mice at a New York University research facility died when the building flooded during the storm.