Thomas J. Lueck (copy) and Tyler Hicks (images) of my hometown paper have reported that in the most prominent, and well-kept, public park in New York City, rats play as though they were squirrels. Notwithstanding municipal efforts to persuade them to relocate. From November 10, 2007, “Where the Rats Come Out to Play”:

The rat that was circling André Thomas’s feet was big and brazen, measuring more than a foot from the tip of its tail to a pointed snout that arched upward to the aroma of Mr. Thomas’s ham and cheese sandwich.

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The encounter might not have seemed all that unusual to many New Yorkers, who have become wearily accustomed to rats bounding along subway tracks or lurking about garbage bins, usually after dark.

But this rat sighting came as a shock to Mr. Thomas because of when and, especially, where it took place — 2 p.m. on a brilliant fall afternoon while he sat on a bench in City Hall Park, a nine-acre jewel of the municipal park system that underwent a $30 million renovation in 1999. The park is a cornerstone of the city’s efforts to revive Lower Manhattan.

“At first I thought it was a squirrel,” Mr. Thomas said as he strode away. “Isn’t this where the mayor works?”

Mr. Thomas’s rodent experience was hardly unusual. If he had looked under the park’s benches and around its meticulously cropped foliage, he would have spotted at least six other rats scurrying around, unconcerned about the humans all around.

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The infestation of rats in City Hall Park, clearly an embarrassment to the city, was acknowledged in interviews by senior officials of the Department of Health and Mental Hygiene, the city’s lead agency for rodent control, and the Department of Parks and Recreation.

“It’s just a big issue down there and we all recognize it,” said Jessica Leighton, the health department’s deputy commissioner for environmental health. Adrian Benepe

, the commissioner of parks and recreation, said that City Hall Park provided “a perfect set of circumstances for rats.”

Indeed, the park’s extensive makeover not only produced a verdant oasis, but inadvertently also created a haven for rats: leafy ground cover in abundance, garbage cans that proved rodent-friendly and droves of lunchtime visitors carrying brown bags with deli sandwiches. Adding to that are large construction projects in the neighborhood, including the World Trade Center site, that have forced rats from their underground homes.

Of course, rats can be found in much of the city’s 2,900 acres of parkland. And they are surely no less bothersome to a parent who sees one in her child’s favorite playground than to someone who is part of the largely adult and professional crowd that gathers each day in City Hall Park.

“I don’t know of a park where you won’t see them,” said Geoffrey Croft, president of NYC Park Advocates, a nonprofit group dedicated to improving public parks. For years, he said, the city has devoted too little money to controlling rodents in the parks.

Mr. Benepe said there was no way to know if the rat infestation in City Hall Park was worse than in other parks. But, he said, the factors attracting them there went beyond the bread crusts, mustard-laden sandwich wrappers, banana peels and other food that visitors jettison every day.

The park, a historic center of civic life since the early 1600s, when the southern end of Manhattan was a Dutch trading colony called New Amsterdam, sits atop an abandoned subway station as well as some of the city’s most intricately layered tunnels, sewers and underground utility equipment.

“The infrastructure provides subterranean highways for rats,” Mr. Benepe said, “and gives them a warm and secure place in the winter.” And a recent stretch of warm winters has reduced the proportion of the rodent population that would normally be eliminated each year by the cold.

Besides work at ground zero, heavy construction nearly surrounds the park, including work on a new subway transit hub being built at Fulton Street and Broadway. “It’s causing a lot of disruption for rats,” he said.

So far, officials said, several anti-rat measures have been taken at City Hall Park. Pellets laced with rodent poison have been inserted into the burrows that the rats have dug under the park’s lawns and foliage, and in boxlike containers designed to keep them from being eaten by dogs, squirrels or birds.