[Rodent Control] Exploring a Modern Ratopolis

Most tourists to the Big Apple go to see Times Square, the Statue of Liberty, etc. I recently participated in a group that explored some landmarks as well: the Brooklyn Bridge, Trinity Church and Battery Park to name a few. The difference is we were not just taking in the sights. We sought a glimpse into the world of urban rats.

We were attending the NYC Rodent Control Academy for three days of instruction by rodentologist (and PCT columnist) Dr. Bobby Corrigan. The Academy takes an intensive look at both the cumulative knowledge of biology and behavior and the latest advances in rodent IPM. But, as important as classroom experience, extracurricular exploring after dark is a must to truly understand the urban Norway rat. The key is to find some good rat sites to visit, lurk in the shadows, and then quietly wait.

EVERYTHING OLD IS NEW. Like several other eastern seaport cities, it’s no secret that New York contains established populations of Norway rats. The impression of the Manhattan skyline of a "modern" metropolis can be a bit misleading. New York City was established in 1625 as New Amsterdam. No one knows for certain when the rat arrived thereafter, but estimates place it at perhaps 150 years later. Now, the problems associated with keeping rat populations low in New York City are directly related to New York’s human population. According to U.S. Census figures, the human population density of New York is estimated to be as high as 40,000 people per square mile. (The population of New York, including unregistered immigrants, may be as high as 12 million people.)

Of course, people have to eat. And this creates lots (and lots) of food-related trash. New York generates mountains of trash every single day. In Manhattan there is no room for large Dumpsters or the hundreds of thousands of garbage cans that would be needed to contain all the trash. So each night, New York places its food refuse out on the curb in plastic bags. When the bags are placed in the same areas in which rats are living, rat infestations result. At the Rodent Academy, we learned 1 pound of food scraps can feed up to 22 rats per night!

COMPLEXITIES ABOUND. The problem is made even more complex by the other support mechanisms for New York’s immense population. NYC is the largest conglomeration of infrastructure in North America. Throughout 33 systems, much of a modern city’s infrastructure is inaccessible (sewers, steam tunnels, utility conduits, defunct subway lines, etc.), and much of which are below peoples’ feet. The result is a myriad of possible harborages and pathways for the burrowing rat. We witnessed large caverns excavated from under city sidewalks which, according to Corrigan, will only be repaired for the process to begin anew.

In addition to these types of harborages, New York City has a surprising amount of what Corrigan refers to as "available earthen space." Manhattan has a patchwork of public parks and greenspaces that provide burrows and natural cover for the opportunistic Norway rat. Even the smallest landscape beds on the perimeters of apartment buildings are vulnerable. There is a lesson to be learned here on the proper design and maintenance of "green spaces" in metropolitan areas and their impact on surrounding pest populations. When park landscaping and popular tourist areas coincide, rat monitoring must be ongoing.

New York City’s rat problem is made more complex by overlapping bureaucracy. Rats in a park may disperse into the nearby subway or vice versa, so the finger pointing may start as to whose rats are whose. One skyscraper may have 30 different leases with each occupant responsible for their own pest management. Add to the equation varied budget amounts for pest management and differing levels of quality in rodent management practices and it becomes almost maddening.

So, how will New Yorkers manage this formidable pest within the constraints of this complex city? The cold, hard truth is, in spite of the best efforts of NYC pest professionals, the Norway rat is likely to persist there in the shadows and underfoot, out of sight and mind to most except those that seek it out. They’ve had more than two centuries and hundreds of generations surviving and adapting to life in the Big Apple. In fact, it’s fair to say that most rats in New York City are not killed by man. Most die from stress caused by competition for food and territory among their own kind.

The author is an Associate Certified Entomologist and technical director, Action Pest Control, Evansville, Ind. E-mail him at srobbins@giemedia.com.

Editor’s note: The approximately 30 attendees of the May New York City Rodent Control Academy were primarily from various municipal departments such as Parks and Recreation, Metro Transit Authority, Housing Authority, Sanitation, etc. The class only has a limited number of seats available for participants outside of NYC. For more information, visit www.nyc.gov/rodentacademy.