It
took a long time of course, but that is best understood by the sharp
change in human density in rural america. The boy with a rifle and
his dog is not able to suppress the population of small carnivores or
even the rabbits although that was always no contest. A thousand
acres is simply too much to patrol and populations have nicely
rebounded over the past fifty years.
The
result is a serious recovery in carnivore population and this leads
naturally to penetration of the urban space along with prey animals
were hunting pressure is even lower.
We
should welcome it of course. Pigeon populations are now quite modest
thanks to resident hawk populations. The hawks still prefer open
fields of course, but it is easy to jump an errant pigeon in the
city. The animals generally respect our space as well and hunting is
mostly nocturnal and we have learned to protect our pets.
As predators big
and small push quickly into North American cities, biologists are
following—and discovering how much we’ve underestimated them.
Coyote number 748 is
not shy. He emerges often during the day, padding along the pavement
of his territory. That territory centers on Soldier Field, the
stadium where the Chicago Bears play. The arena is in the core of the
city, flanked to the west by eight lanes of Lake Shore Drive, and to
the east by a sculpted park and a marina with room for a thousand
boats. In April, Stanley Gehrt, an Ohio State University biologist
who has tracked more than 800 coyotes in Chicago with GPS collars
over the last 14 years, traced number 748 to his den. It was on
the top level of a nearby parking garage, underneath some concrete
slabs. And inside? Five healthy pups. Never before has Gehrt found a
mating pair establishing a litter so deep downtown.
“They’re off to a
good start,” Gehrt told me, his voice edged with awe. “These
coyotes constantly remind me that we’ve got to broaden our view of
what we consider to be wildlife habitat. What someone else might
consider a junky, useless piece of ground, well, that may actually be
the difference between life or death to a coyote.”
Over the past 100
years, coyotes have, quite literally, been taking over America. They
are native to the continent, and for most of their existence these
rangy, yellow-eyed canids were largely restricted to the Great Plains
and western deserts where they evolved. But after wolves and cougars
were exterminated from most of the United States by the 1800s,
coyotes took their place. Colonizing some areas at a rate of 720
square miles per year, coyotes now occupy—or “saturate,” as one
scientist I spoke with described it—nearly the entire continent.
(Long Island is a notable exception.) The animals are now the apex
predators of the east. And they’re proving so resourceful that even
the last stronghold—the urban core—represents an opportunity to
flourish.
Gotham Coyote Project
from JSTOR on Vimeo.
Coyotes may be the
most driven carnivores to penetrate modern cities in recent years,
but they’re hardly the only ones. Raccoons, foxes, and skunks have
long been prolific urban residents. And now bobcats, cougars, even
grizzly bears—predators that symbolize wilderness, who typically
require a lot of space and a stable prey base, and defend
their territories—are not just visiting but occupying areas that
scientists used to consider impossible for their survival. Dozens of
grizzlies now summer within the city limits of Anchorage. The most
urban cougar ever, a male named P22, has been canvassing Los Angeles’
Griffith Park for more than two and a half years. Bobcats prowl
the Hollywood Hills and saunter near skyscrapers in Dallas. And in
New York City, a predator is returning that hasn’t been seen since
Henry Hudson’s day—the fisher, a dachshund-sized member of the
weasel family with a long, thick tail. This spring, a police officer
named Lenart snapped the first NYC photo of one, skulking on a Bronx
sidewalk at dawn.
These are not isolated
incidents. Instead, they’re signs of a broader trend: success.
Globally, almost a third of wild species (both plants and animals)
that the IUCN Red List assesses are threatened. But in North America,
many mammals and birds are bouncing back from historic losses. (The
naturalist Ernest Ingersoll, lamenting the dearth of wildlife in
1885, marveled at colonial-era reports of “deer thronged everywhere
along the Atlantic seaboard in almost incredible numbers.”)
History is being
revisited. The comebacks are bringing people and wildlife closer
together,especially in the densely populated eastern United States.
“There’s still a [public] perspective that we are pushing into
animal territory, and pushing them out,” says Roland Kays, a
mammalogist at the North Carolina Museum of Natural Sciences and
North Carolina State University. “In fact, at this point, it’s
the opposite. Animals are coming back into our territory—our cities
and suburbs—more than they ever have before.”
The causes are
complex: a tossed salad of legal protections and habitat
conservation, hunting restrictions, reintroduction programs, regrowth
of forests in former farmland, and suburban sprawl. On a
species-by-species basis, scientists still have much to untangle
about why North American carnivores are increasingly in our midst,
how they’re changing cities, and how cities are changing them. But
researchers are learning—and learning quickly.
That’s because the
North American wildlife revival is presenting remarkable new
opportunities for discovery. Indeed, over the last few decades, a new
genre of researcher has emerged: the urban wildlife biologist.
According to a 2012 literature review, more than 30 times as many
urban wildlife studies are being published now than were in the
1980s. And many new scientific journals have blossomed to publish
them.
Gehrt’s coyote
research has filled many gaps, such as estimating population size in
Chicago (2,000 adults, and likely double that with young),
tracking what urban coyotes eat, how they
maintain mates and territories, and how likely they are
to avoid people. What was intended as a one-year study at the
county’s behest is now one of the largest analyses of urban
carnivores in the world. It and similar efforts for coyotes and
wild cats near Los Angeles have inspired scientists in
municipalities such as Albany, Atlanta, Denver, Calgary, and now New
York City to document burgeoning predator populations. As they do,
they’re discovering howthese animals are
changing—behaviorally, physically, and perhaps even
temperamentally—to exploit the landscapes we all now call home.
*****
In 2000, the same year
that Gehrt tagged his first coyote, near O’Hare airport, Roland
Kays strapped a few motion-sensitive cameras to trees in a forest
fragment between the cities of Albany and Schenectady. The patch is
bisected by the interstate, which you can take to get to the mall or
airport a few miles away. Kays, then a curator at the New York State
Museum, was hoping to catch a red fox on his camera “traps,” or
maybe a coyote. To his astonishment, the SD card recorded a low,
limber predator with dense brown fur: a fisher. “Fishers weren’t
even on my mind,” Kays says. “I never thought they’d be there.”
For one, fishers
weren’t common. The animals are native to the continent’s
northern forests, and overzealous logging and trapping for the fur
trade nearly wiped them out of the U.S. and much of Canada by 1940.
Trapping bans took hold around that time, and fishers are now
recapturing original territory in the most crowded swath of the
United States: the northeast.
As more fishers turned
up on cameras and tracking forays, Kays realized they were thriving,
able to find enough space and cover near malls, split-level
colonials, and areas of 1,134 people per square mile. But the species
had been described in countless scientific texts as
requiring deep evergreen forests. Either scientists’ assumptions
about fishers were wrong, or the weasels were themselves changing to
take on the suburbs.
The puzzle fascinated
Scott LaPoint, who had studied martens in the Adirondacks as an
undergrad. In 2008, LaPoint began working on his PhD thesis with Kays
to find the answer. The team investigated fishers’ diets, their
competitors, and their range changes. Over several winters, the pair
tracked eight animals with GPS collars custom-fit for their narrow
necks.
Kays and LaPoint, who
is now a postdoctoral researcher at the Max Planck Institute for
Ornithology in Germany, released their findings this past year. They
saw that fishers navigate urbanized areas via connected snippets of
forests— what biologists call corridors. But the animals will cross
roads and ball fields, or slink past homes when they need to, usually
at night, unbeknownst to residents.
Why are they
flourishing in the east? “We found support that eastern fishers are
experiencing what’s known as mesopredator release,” says
Kays. “That means they overlap with fewer predatory species than
they used to. There are no cougars; there are no wolves.” Without
many big competitors to fear, middle-sized predators, or
mesopredators, are free to change their habits: they can hunt in a
wider range of places or times. They can also pursue larger prey (for
fishers, that means hefty snowshoe hares, porcupines, or deer
roadkill) without getting beaten to it or bullied. Scientists suspect
that mesopredator release is fueling coyotes’ incredible expansion
as well.
Most intriguingly,
LaPoint and Kays discovered that the bodies of eastern fishers are
actually getting bigger over time. These carnivores seem to be
evolving to better catch larger-bodied prey by becoming larger
themselves. A big, well nourished fisher is more likely to survive in
new, challenging environments. “They’re getting bigger where
their populations are expanding,” says LaPoint, which the team
documented by comparing hundreds of museum specimens collected from
the 19th century to the present. That’s brisk, evolutionarily
speaking. “Within a century, more or less,” he says. “It’s
pretty crazy.”
The rub is that this
“wilderness” species seems to be quickly adapting to our
presence. In persecuting North America’s biggest carnivores, we may
be encouraging medium-sized ones to spread directly into the areas we
now live, and in some cases, actually evolve into bigger, more
resourceful predators.
*****
Now that fishers are
stealing south through Westchester and into New York City, Kays
speculates that their prospects are good in the country’s largest
metropolitan area given its rodent hordes. Those prey are sustaining
New York City coyotes just fine. The canids are established in the
park-filled Bronx, just north of Manhattan (and occasionally pop into
Central Park or even further downtown).
Wildlife biologists
are now seizing an opportunity that this city uniquely affords: a
chance to document the leading edge of coyotes’ American invasion
in real time. The only large tract that coyotes have not yet
colonized in the United States lies just to the east—Long Island.
“There’s primo habitat out there,” says Mark Weckel, a
postdoctoral researcher at the American Museum of Natural History.
“It’s just a matter of them getting to it.”
Weckel and
his frequent collaborator Chris Nagy, who directs research
at Westchester’s Mianus River Gorge Preserve, are tracking this
historic passage. They began in 2011 by launching the first
large-scale camera-trap study in New York City. On a muggy July day I
met them in the shade of a Bronx park. Commuter trains roared by
regularly. There, Weckel and Nagy were siting trail cameras to
photograph coyotes, and hopefully pups, in order to discover what
kinds of areas suit them in the boroughs. Then, with collaborators,
the researchers hope to predict similar habitats that coyotes might
colonize in Long Island so they can monitor their ecological and
social impacts pre- and post-arrival. That’s about as close to a
controlled experiment as you can get in ecology. “You often don’t
have opportunities to measure before an interesting thing
happens,” says Nagy.
Coyotes’ final surge
may already be underway. As Weckel and I walked the park’s
well-trod trails, he told me that he recently retrieved—in a yellow
taxicab—a rare dead local specimen for the American Museum of
Natural History’s collection. The body was lying along the
northbound side of a Queens parkway about a mile from the Long Island
border. To get there from the Bronx, Weckel said, the coyote must
have swum across the East River or walked along one of two bridges.
“I’m pretty
ecstatic,” he said. “I mean, I’m sorry it died. But we’ve
been monitoring [a nearby] park for three years and hadn’t found
coyotes there yet.” He and Nagy have been collecting genetic
samples from coyote scat, so they’ll be able to evaluate the
specimen’s DNA to see if it dispersed from a breeding population in
the Bronx.
“Coyotes are my
favorite animal,” says Nagy. “I like them because they’re smart
and adaptable—I find that personality admirable.” This bold
coyote is just a sign of more to come.
*****
Researchers are now
asking whether individual predators that are particularly intrepid in
cities—such as this Queens coyote, Chicago’s number 748, or the
Bronx fisher—are genetically predisposed to such behavior. These
animals could pass their adventurous personalities to their
offspring, and so on, presumably inclining future generations to push
the urban envelope further. Gehrt initiated a DNA study this year
that will compare genetic markers of Chicago coyotes to those
identified in the domestic dog genome that correlate with boldness,
inquisitiveness, and other personality traits. “We know that
certain alpha pairs have been more successful than others in terms of
raising litters that become successful themselves,” says Gehrt. “If
it’s genetic, then we are inadvertently selecting for a certain
kind of coyote.”
What about larger
predators that have less apparent flexibility and currently have
smaller populations, such as cougars or wolves? Might they eventually
adapt to live more in our midst? “I think this is going to be a
very exciting next few decades, because we’re going to get to
answer that question,” says Gehrt. “The easy answer is that
larger predators will come up to cities, but they probably won’t be
able to exploit them.” He pauses. “But the real answer is that we
don’t really know. We’re moving into uncharted waters here.”
While the public might view that future with trepidation, the new ur
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