State of the Planet

News from the Columbia Climate School

Scientists Are Mapping New York City Wildlife. And We Don’t Mean Rats, Squirrels or Pigeons.

New York is increasingly populated by wild native animals that adapt well to urban environments. Here, a raccoon trapped in Brooklyn. (All photos unless otherwise noted: Kevin Krajick/Earth Institute)

A possum walks into a bar. That’s the start of a joke, right? At least it should be; the reader is hereby invited to think up the rest and come up with the punch line. In the meantime, a possum did actually belly into the crowd at Temkin’s Bar in the Greenpoint section of Brooklyn one night this summer. Before it was able to order a drink, a young woman (not from here—Alaska, she explained) grabbed it, marched it outside dangled by the scruff of its neck, and set it on the sidewalk. Patrons hooted and cheered as the possum scuttled away and disappeared to parts unknown.

New Yorkers, already living in the United States’ most densely populated city, are now sharing space with an increasing number of wild creatures that are good at adapting their diets and hiding places to urban environments. The city has been expanding its green spaces for decades, and now some 78,000 acres of wetlands, grasslands, forests, cemeteries, parks and community gardens provide habitat and food. So do nearby dumpsters, trash cans, back yards, vacant lots, sewers and abandoned buildings.

There are possums, raccoons, deer, coyotes (one turned up last year in Central Park), foxes, rabbits, groundhogs and skunks. In the waters, river otters and beavers (after a nearly 200-year absence, one was recently seen running along a promenade near the Williamsburg Bridge). In the air, peregrine falcons, red-tailed hawks, bats and rare native bees.

Above and below, Columbia University grad student Myles Davis sets up camera traps in Brooklyn’s Green-Wood Cemetery, which abounds with animals.

More animals living among people and their pets means more potential disease spread, property damage and occasional physical confrontations. Among other things, there are concerns for rabies, raccoon ringworm (rare in people, but eats at the eyes and brain, and can kill you) and a canine form of coronavirus. Wild animals also can play intermediary roles in the transmission of tick- and insect-borne diseases.

Yet there has been little systematic effort to study the city’s wildlife populations, dispersal patterns, ranges, inter-species contacts, or diets. “A lot of New York is a dead zone for wildlife research—raccoons and things like that are just regarded as trash mammals,” said Myles Davis, a Columbia University graduate student working as part of a project to help fill the gap. “They’re part of the environment. We need to understand them so we can promote human-wildlife coexistence.”

Davis’s part consists of 40 camera traps he periodically sets out along a 50-kilometer transect of green spaces spanning Brooklyn, Queens and Long Island’s Nassau County. His main quarry: medium-size mammals, or so-called mesocarnivores, such as raccoons and possums. Another grad student is trapping animals, taking biological samples and fitting animals with radio collars to track their movements. Others are studying ticks and mosquitoes along the transect, to chart how they might interact with mammal hosts to spread Lyme disease or other ailments. Bird counts and surveys of humans regarding their encounters with wildlife are planned.

Columbia professor Sara Kross (left) and grad student Laura Dudley Plimpton admire a pile of raccoon scat at Green-Wood. The scat (below, in closeup), contains DNA information, and an accounting of what the raccoons are eating,

The project recently became part of the Urban Wildlife Information Network, a collaborative of some three dozen U.S. and Canadian cities, along with a few in Europe and Africa, which use the same research protocols to study and help manage wild city animals.

“All this wildlife is interacting with each other, and interacting with us. It’s important to know who’s out there,” said Maria Diuk-Wasser, a disease ecologist affiliated with the Columbia Climate School who studies ticks and mosquitoes, and supervises much of the other research.

One hot spot for research is southern Brooklyn’s 478-acre Green-Wood Cemetery. Dating to the 1830s, its rolling grasslands dotted with big old trees are permanent home for some 570,000 human residents—and an estimated 500 raccoons, along with possums, skunks, groundhogs, birds, bats and other wildlife including feral cats (not part of the current research).

Around noon one recent steamy summer day, Davis was there with several colleagues to install a half-dozen wildlife cameras. The cameras—modest little boxes usually strapped to a tree—are programmed to sense both motion and temperature, and snap pictures automatically when a creature passes by.

Sara Kross scans Green-Wood Cemetery’s trees for raccoons, which like to hang out there during the day.

Davis had his spots mapped out in advance. He installed the first camera on an English holly tree just inside the cemetery fence from busy Fort Hamilton Parkway. The tree grew next to the resting place of Walter Irving and His Wife Sarah F. (1876-1949 and 1888-1964, respectively).

As Davis worked, his fellow grad student Laura Dudley Plimpton and their advisor Sara Kross enthused over a pile of raccoon poop piled on top of a nearby grave marker. Raccoons are fastidious, they explained; they use the same spot repeatedly instead of just going anywhere. By collecting poop, the team hopes to build a database of raccoon DNA and diet. “There’s a Burger King across the street,” noted Plimpton drily. “I bet this raccoon is an obese one.”

Green-Wood welcomes research, and in fact helps fund Davis’s work. Presently Sara Evans, the cemetery’s manager of horticulture operations and projects, joined us. She pointed out that in addition to relatively undisturbed habitat amid a sea of concrete, asphalt and traffic, the cemetery provides natural food sources: acorns, hickory nuts, birds’ eggs, insects. Also, some visitors leave food on the graves of loved ones—offerings that are in fact consumed, but not by the dearly departed. But the biggest food source, she said, is unsecured trash or pet food left in neighboring back yards, alleys and along curbs. “Some of the neighbors blame us for the raccoons getting into things,” said Evans. “I keep telling them we have a trash problem, not a raccoon problem.”

As Davis set up another camera, Kross pulled out binoculars and scanned nearby trees, where raccoons and other animals like to hang out during the day. Most urban-adapted mammals are excellent climbers not just of trees, but fences, drain spouts, trellises and other features. “Can’t see them, but I know they’re out there,” said Kross.

Images of wildlife caught by camera traps. Above, a coyote crossing Meadow Brook golf course in Long Island’s Nassau County, close to the New York City border. Below, more animals. (All camera-trap photos courtesy Myles Davis)
Possum, Alley Pond Park, Queens.
Raccoon, Green-Wood Cemetery, Brooklyn.
Skunk, Green-Wood Cemetery, Brooklyn.
A rare piebald deer, Meadow Brook golf course, town of Nassau.

A few weeks later, Davis was driving around the boroughs in a car borrowed from his sister to inspect previously installed cameras and set out new ones. First stop was Lincoln Terrace Park, a grassy 21-acre plot in Brooklyn’s Brownsville neighborhood. Davis’s first task was simply to ensure the camera he had previously installed was still there. He grew up in Brooklyn, so he knows: people will steal anything. Amid the tennis courts, lawns and playgrounds, nestled in a little patch of trees and brush, yes, the camera was still there. Previous visits showed it hadn’t produced much of interest yet, he said—pretty much just squirrels—but he downloaded the camera’s data into his laptop for later viewing. He put the camera back with a fresh battery, and we hopped back in the car.

On the drive, I learned that Davis is already a seasoned wildlife researcher. After college, he had taken jobs to help study crocodiles in Florida; birds and frogs in Costa Rica; and red colobus monkeys in Zanzibar. Once, he spent three years in Thailand, where he helped study the behavior of elephants used in tourist expeditions. His last job there: chasing down big, fast-moving king cobras and pinning them with a hook so they could be radio-tagged by more senior researchers. He became so good at it, locals started calling him to remove snakes from their homes.

After king cobras, aren’t dumpster-diving urban raccoons a bit of a comedown? “Not at all,” he said. “I’m interested in human-wildlife conflicts. I want to use my research to rethink how we deal with that.” Community outreach is important, he said. He is working with the Girl Scouts and local high schools to involve them in field work, and plans to use citizen volunteers to sort through the thousands of images the cameras produce.

Above, Davis checks a camera at City Line Park, a narrow strip of green between two busy avenues. Below, setting up a camera at Forest Park Golf Course in Queens.

Next stop was City Line Park, straddling the Brooklyn-Queens border—actually not so much a park as a wide median between two busy avenues lined with brick buildings. There are trees, but the grass is mostly dead and rutted, and strewn with trash. Locals use it to stage vehicles for drag races, said Davis, and lots of homeless people put up there at night. As an experiment to see if animals used it too, he had strapped a camera to a small pine tree. “Ah, it’s still there!” he shouted in surprise. Then he checked the data: 6,000 photos in just four days. This had to be mainly human activity. He packed up the camera for use at a more promising spot.

We drove over to Forest Park Golf Course in Queens, where a manager named Bob already knew Davis from past visits. Bob told told him to help himself to a golf cart. Davis did, and we put-putted along winding paths past several parties of golfers to an expansive lawn. Here, he strapped a camera to a huge beech tree near the 12th hole. Again, a bit of an experiment—a wide-open space, and people passing by, but anything can happen, especially at night, he said.

Succeeding stops included the 5.4-acre Joseph F. Mafera Park, on a dead-end street in northern Queens. Most of it was paved for playing courts, but there was a bit of green space. Davis fastened a camera to a big maple at the park’s edge, as summer-camp counselors and three dozen preschoolers wearing matching red shirts marched by. Ten or 15 feet from the tree, on the other side of a ramshackle chain-link fence, the M train roared by on elevated tracks.

Above, Joseph F. Mafera Park in Queens has just a small patch of green space that wildlife might use. Below, a camera attached to a tree in Brooklyn’s Brower Park shares space with a homeless camp.

Last stop was tiny Brower Park, in Brooklyn’s Crown Heights neighborhood. Kids were running around, families were strolling, young men were shooting hoops. Davis had a camera there, hidden in a clump of bushes backed up against the brick wall of the Brooklyn Children’s Museum. One or more homeless people evidently inhabit the spot; there were a couple of reclining chairs, a milk crate, plastic bottles, discarded clothes and some used toilet paper. But the camera was still there, and working. Davis downloaded the data and put the camera back on its tree.

* * * * *

Four in the morning, Green-Wood Cemetery. Outside on surrounding blocks, scattered street lights and store signs cast a dim glow over the neighborhood’s abodes and businesses belonging to the living. Inside the city of the dead, it is nearly pitch black.

Laura Plimpton and another grad student, Richie Konowal, had been there the previous sunset to set out boxy cage traps in hopes of capturing animals, mainly raccoons. Plimpton, also an experienced wildlife hand (New York suburbs, rural New England, Botswana) had selected the cat-food bait with care. “I go with the fishiest smelling brand I can source. Since I’m competing with McDonald’s and Dunkin’ I feel it has to be as enticing as possible,” she said. She has no proof yet, but believes Fancy Feast Paté is preferred to Friskies. “Sometimes I add in a little canned tuna to really add a kick,” she said.

In the predawn dark at Green-Wood Cemetery, Laura Plimpton opens a trap to release a skunk. She has been sprayed more than once.

It was time to make the rounds and see if they had caught anyone. They drove and walked through the dark to obscure corners of the cemetery where they had placed the traps. Finding their way with head lamps through overhanging foliage and filmy spider webs, they started collecting animals.

The first couple of traps were empty. Then they came upon one occupied by a fair-size raccoon; the animal showed no reaction when they picked up the cage and put it in Plimpton’s car. Eventually, three others turned up, all looking well fed and healthy. Also, three skunks, a possum and an enormous black cat, which they eventually turned loose. The researchers were not planning to collar skunks today; Plimpton gingerly opened their cage doors and propped them open with sticks so the skunks could exit at their leisure. She has been sprayed more than once—comes with the territory, she said. She currently also had poison ivy on both her forearms, acquired a couple of nights ago while brushing against unseen vegetation in the dark.

Above, veterinarian Sarrah Kaye examines a sedated raccoon captured at Green-Wood Cemetery. Below, fitting a radio-collar to track the animal’s movements. (The collar is designed to fall off after about 6 months.)

The researchers ferried their catches to an alley sandwiched between a brick building used for storing and repairing cemetery vehicles, and a row of back yards backing up to the burial ground. Here, they set up a folding table and bunch of equipment for “processing” the animals, as they called it. This would require the services of a veterinarian. Sarrah Kaye, vet and general curator for the Staten Island Zoo, had signed on, and it was still dark when she showed up.

Kaye provides cares for everything from tarantulas to leopards, so this was a pretty routine job for her. One by one, Plimpton and Konowal corralled the animals in their cages so Kaye could jab them through the bars with a sedative shot. Most, but not all, submitted quietly. “No, don’t worry, it’ll be OK,” Plimpton cooed to one hissing raccoon who definitely was not enjoying the situation. Aware that the animals could be carrying diseases, everyone wore masks and gloves. (The cemetery regularly puts out baits laced with rabies vaccine to minimize at least that concern.)

Once each animal was inert, Kaye gently lifted it out and laid it on the table. She stroked each gently and examined it. To sample for diseases, Kaye took oral, nasal and rectal swabs, and a small blood sample. Meanwhile, Plimpton rigged up a radio collar, which was fitted loosely around each animal’s neck. Once everything was set, they placed the animals back in their cages, which were covered with blankets to keep their occupants calm upon awakening.

Above, grad student Richie Konowal weighs a captured possum. Below, Sarrah Kaye checks the possum after sedation, discovering babies in its marsupial pouch.

As Kaye lifted the possum out of its cage, she remarked that it was a female—and was carrying babies in her marsupial pouch. Her gloved hand briefly revealed some tiny pink blobs on the animal’s underside. Possums can carry 10 or 12 at a time—possibly one key to their success, along with the fact that, like most other urban animals, they will eat just about anything.

Presently, the sun came up, and the team worked for another hour or so. When they were done, Kaye packed up and headed to her day job. The researchers wanted to make sure each animal was fully alert before setting them loose, and checked periodically under the blankets.

While waiting for the animals to wake up, Plimpton opened her laptop and showed me the travels of some already-collared raccoons. The collars ping each animal’s location to a wifi network every 15 minutes at night, when they are most active. Bluetooth devices placed around likely visiting places such as dumpsters also detect when collared animals are visiting. “That way, we can tell where animals are socializing, and if different species are making contact with each other,” said Plimpton.

Free at last; a radio-collared raccoon streaks away after being released from its trap.

On the laptop, zigzagging lines lain over a local map showed some raccoons ranging only within the cemetery; she called these “cemetery raccoons.” One made the same nightly straight-line pilgrimage from one end of the cemetery to the other, for reasons unknown. Other raccoons embarked on regular expeditions a block or two out into surrounding neighborhoods, undoubtedly looking for food. Plimpton called these “urban raccoons.” Some seemed to like variety, and explored different places on different nights. But at least one could be seen sticking to a tight pattern along the same few blocks each night. “Raccoons do the weirdest things,” she said.

It was time to set the animals loose. Plimpton opened one cage and stood back, but the raccoon did not seem interested in leaving. “Come on, you can go,” she said, and dragged the blanket across the back of the cage to coax it out. Finally the animal exited. It headed for a tall, straight tree, which it scaled with astounding speed, despite the lack of any branches for about the first 30 feet.

A few minutes later, Konowal freed another raccoon. This one did not hesitate; it streaked a few dozen feet away, and turned to look back with what seemed like a sullen expression. Then it disappeared into a patch of high vegetation bordering a neighboring back yard.

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