D.C.’s War On Rats Goes Digital


Complaints about rats in D.C. have more than doubled since 2015, but the rodents pose an age-old problem for the city. Fifty years ago, it was estimated that the District had as many rats as humans. The situation got so bad that Congress declared a War on Rats and had a staff of more than 100 exterminators fighting on the front lines.

The latest rat boom seems to stem from warming winters (fewer rats die, more baby rats are born), and a growing human population (who unwittingly provide food and shelter for the rodents). This time, the District is looking into a high tech solution to combat the rats: using computer modeling and data to hunt them, enlisting the help of The Lab @ DC, a new team in the District government that uses data science to tackle urban problems. The computer model is still being developed, but in early testing, it’s more effective at finding rat infestations than the city’s current approach: eight exterminators patrolling the city in pickup trucks marked “Rodent Control — Frequent Stops.”

Responsive government isn’t always the best government

The trucks do indeed stop frequently: in FY 2017, there were more than 5,000 complaints about rats to 311, the city’s service request line. The number is up from about 2,000 in FY 2015.

The exterminators focus their efforts almost entirely on responding to those complaints. They’re very responsive: often, the exterminators will show up in an alley just a day or two after receiving a complaint, and they follow up the next week.

But there’s a problem with this responsive approach. Not everyone complains equally, so exterminators may be missing blocks where residents for whatever reason don’t call 311 as much. For example, research suggests that social factors, including immigration status and exposure to police force, affect the likelihood that someone will call 311.

“There’s some citizens that don’t call in that have real bad issues, and there’s some that don’t have serious issues that call in a lot,” said Michael Jacobs, the exterminator tasked with patrolling Ward 1, which data indicates is the District’s rattiest.

On a recent morning, Jacobs was working his way up an alley in Park View, poisoning rat burroughs, when a resident hollered down from an upstairs balcony.

“That dude right there be out here everyday,” said Linwood Davis, nodding toward Jacobs. “They need to give him something more powerful though. A couple rats dropping, but it seems like two will drop and you’ll see five more coming.”

Davis has lived here for most of his 55 years. He said there have always been rats, but never this bad. “The rats control this area, man,” he said.

He frequently calls 311 to report them. “311, man I been calling them so much, they got my name on speed dial.”

Three recent casualties of D.C.’s war on rats, in an alley staircase in Park View.Jacob Fenston / WAMU

311 ‘frequent fliers’ bias data

“It’s great that people call in to 311,” said Peter Casey, a data scientist and a fellow with The Lab. “It’s like crowdsourcing this data.” But, while crowdsourced data can be useful, it doesn’t create an accurate picture of the city — for one thing, power users like Linwood Davis can bias the data.

So Casey has been working on a computer model to predict which city blocks are most likely to be rat-infested — based not on 311 complaints, but on all the variables in the environment that allow rats to flourish.

The team at The Lab scoured data from just about every city agency — everything from property tax records to business licenses — to get information on things like building age, building condition, population density, number of restaurants, size and condition of alleys, location of sewer grates and the location of parks and community gardens.

Peter Casey with The Lab @DC shows a brainstorming white board.Jacob Fenston / WAMU

The model has produced a map of the District with every block in a different shade of red. There’s a clear pattern: the most densely populated neighborhoods show a higher likelihood of rat infestation. Dark red radiates from downtown up through Dupont, Columbia Heights and Petworth, out along H Street and in Trinidad, and in Georgetown and up Wisconsin Avenue.

“When you have lots of people living in close quarters you’re producing more and more trash in a smaller and smaller area and you’re producing more potential food for rats,” Casey said.

Building age is another important factor, according to Casey. “When you have older infrastructure that is degrading, rats have more opportunities to burrow in and get settled and find shelter,” he said.

An individual human could create a similar-looking map by simply plotting out 311 complaints. But Casey says that’s three-dimensional thinking — latitude, longitude and 311 calls.

“What the machine learning model is doing is dozens or even hundreds of dimensions of thinking,” he said.

They’re still testing the model, but if it works, it could help the city be more methodical and proactive in hunting rats.

The Lab’s map of predicted likelihood of rat infestations by census block.CapSTAT on Rats / Office of The Mayor

Farming rats

As any rat expert will tell you, using data to find rats isn’t exactly new.

“The principles of data collection for urban rat control began in the 1940s, actually,” said Bruce Colvin, a rodent consultant who has advised cities all over the country. According to Colvin, the modern era of urban rat control began during World War II, when the U.S. government started investing in research because of concern about contamination of food and the spread of disease.

At that time, researchers developed a systematic approach, involving block-by-block surveys of conditions. Each block would be coded for rat risk, and prioritized on that basis. The Lab’s computer model basically is doing the same thing, but without the expense of an army of rat surveyors combing every city block.

Despite decades of research backing up this systematic approach, however, most cities don’t do it.

“Urban programs around the United States fail because they get into a complaint-driven, chase-the-rat mentality, rather than systematically looking at each block and its risk factors and solving them in a sustainable way,” said Colvin.

Gerard Brown, program manager of D.C.’s rodent control program.Jacob Fenston / WAMU

Gerard Brown, who heads D.C.’s rodent control program, said that right now there are so many complaints coming in, responding is all his small team can do.

“Right now we’re focused on those 5,000 complaints we receive. We don’t have to predict where they are; we know.”

He said the predictive analytics model will be a good tool to use, “as soon as we get on top of the increase in complaints.”

But Bruce Colvin said extermination campaigns alone can have a terrifying unintended consequence:

“When you lower the number of rats, there’s less competition for food, which means the reproduction rates can soar. And the numbers may come up higher than before you started trapping and poisoning rats.”

To avoid that, Colvin said extermination can’t happen alone. You have to also get rid of the food sources rats thrive on. In other words: trash. Otherwise, he said, you’re just “farming rats.”

Pick up your pizza

From her dining room window in Capitol Hill, Sylvia Csiffary has a perfect view of the rat activity in her alley.

“Right outside my window there are five commercial-sized dumpsters,” she said, opening the window.

Csiffary lives off Pennsylvania Avenue, behind several restaurants, and she’s spent the past six years waging her own small war on rats. She rallied neighbors and cajoled restaurant owners. She even created a Facebook page, filled with her photos of rats eating trash. Her favorite is of a rat feasting on a bin of used cooking grease.

“I was horrified, and so was the rat horrified when it saw me with my iPhone,” she said.

She also waded into the alphabet soup of city agencies responsible for sanitation — from DPW to DOH to DDOT.

“It was so frustrating to have to learn all of this about the way the bureaucracy was set up and how it worked,” she said. These days, the alley looks better, but the war isn’t over: there are still rats.

Back in the alley in Park View, the problem isn’t restaurants, but residents. Just about every residential trash can has a hole in it.

“Most everybody’s trash can like this been chewed through though,” said longtime resident Linwood Davis.

A trash can in Park View, with a hole in its lid chewed through by a rat.Jacob Fenston / WAMU


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