D.C. Researchers Have Spent The Last Two Years Compiling Photos For A Cat Census Scientists will soon have the first ever population count of Felis catus in the District of Columbia.
From NPR station

WAMU 88.5

NPR logo D.C. Researchers Have Spent The Last Two Years Compiling Photos For A Cat Census

D.C. Researchers Have Spent The Last Two Years Compiling Photos For A Cat Census

A cat captured on camera by cat census workers. Courtesy of DC Cat Count/ hide caption

toggle caption
Courtesy of DC Cat Count/

Imagine having 6 million photos of animals — including thousands of cat photos — sitting on memory cards and computer hard drives. Your task: sort through them all, and count each individual cat.

Bill McShea doesn't have to imagine it — he's living it.

"I wish somebody would give me a computer that could match up these cat photos. But right now it's all human eyes," he says.

McShea is a wildlife ecologist with the Smithsonian Conservation Biology Institute. For the past two years, he's been one of the leaders of the DC Cat Count to get an estimate of just how many felines there are in the District. McShea and a small team of researchers are using techniques typically deployed to estimate populations of wild animals.

"Usually we're in protected areas or in a national park in China or Borneo or something like that," says McShea. "Here we are in a very urban setting." Researchers put wildlife cameras — automatically triggered by movement — in backyards, alleyways, street corners and triangle parks across the city. They've just finished collecting the data, and are now in the process of analyzing it.

Courtesy of DC Cat Count/
Courtesy of DC Cat Count/
Courtesy of DC Cat Count/
Courtesy of DC Cat Count/

So ... why would anyone spend three years counting cats?

Article continues below

Lauren Lipsey with the Humane Rescue Alliance says getting an accurate cat population number will help her organization manage feral cats in the city. The group operates animal shelters and provides animal control services in D.C. and is partnering with the Smithsonian on the cat count project.

"If we don't know the baseline population of cats, it makes it impossible to measure the effectiveness of various population control policies or strategies."

For example, says Lipsey, trap-neuter-return has long been one of the key programs in D.C. and across the country, aimed at reducing feral cat populations. Feral cats are trapped, spayed or neutered and then returned to the community. It's seen by many animal-lovers as a humane way to prevent unchecked cat population growth.

"Of course, we know that it affects those individual cats with whom we're interacting," Lipsey says. "But without knowing a baseline population estimate, we don't have a sense of the impact on the overall population."

Many scientists and bird-lovers blame outdoor cats, including ferals, for killing billions of birds and small mammals each year — and for the extinction of dozens of species. But without an accurate count, or any clear data on where in the city cats are concentrated, it's impossible to assess cats' true impact on the local ecosystem.

So ... how many cats are there in D.C.?

Researchers placed cameras in 1,530 locations, strategically sited across the city. Each location was surveilled for 15 days, for a total of 22,950 days of observation. Of the roughly 6 million photos captured, about 20% are of cats.

Cameras also caught many other creatures. The most common animals captured were dogs, followed by cats, squirrels, deer, rats and raccoons. There were also some rarer urban inhabitants: flying squirrels, coyotes, beavers and at least one bobcat.

Not the kind of cat we were looking for! A bobcat caught on camera near the C&O Canal. Courtesy of DC Cat Count/ hide caption

toggle caption
Courtesy of DC Cat Count/

"We were surprised at the abundance of species other than rats and cats," says McShea. In fact, the cat count may shed as much light on the city's other animals residents as it does on its cats. All the photos are being uploaded and tagged in the citizen science database, eMammal.

To come up with a total cat population estimate for the city, researchers are going through each photo to eliminate duplicate shots of the same cat. Once that work is done, a few months from now, the team will be able to model cat density throughout the District and arrive at a population estimate.

"Cats are very unevenly distributed across the city," says McShea. "There are hot spots out there. But the flip side of that is there are places that are relatively empty of cats."

Hungry beaver. Courtesy of DC Cat Count/ hide caption

toggle caption
Courtesy of DC Cat Count/

While the final analysis of D.C.'s cat population is still months away, McShea and Lipsey say there is at least one data point that stands out, in terms of cats' impact on the environment. There were very few cats in the city's largest parks, where wildlife could be most threatened by the presence of cats. For example — D.C.'s biggest, wildest park, Rock Creek Park, was "almost absent of feral cats or semi domesticated cats," according to McShea.

The cat count project will be complete in 2021, at a total cost of $1.5 million, funded by a number of nonprofits and charities.

Questions or comments about the story?

WAMU 88.5 values your feedback.

From NPR station

WAMU 88.5