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outside the borders of these ostensi-
bly protected areas. “We appear to be
making vast tracts of land inhospitable
to most forms of life,” one co-author
grimly commented, “and are currently
on course for ecological Armageddon.” “big implications for how people think
about the value of nature.” And chang-
es in human attitudes about nature can
have dramatic effects on the ability of
wildlife to survive in human-dominated
landscapes.
That came on the heels of a July report
in the Proceedings of the National Acad-
emy of Sciences describing a “biologi-
cal annihilation” in which “as much as
50% of the number of animal individuals
that once shared Earth with us are al-
ready gone,” with likely “cascading cat-
astrophic effects on ecosystems,” and
on economic and social services “vital
to sustaining civilization.” In particular,
global vertebrate populations — from
elephants to amphibians — declined by
58 percent from 1970 to 2012, a 2016 re-
port noted, with losses likely to reach 67
percent by 2020. That’s two-thirds of all
vertebrate animals on Earth vanished in
the lifetime of a person not yet 50. For instance, persistence of old cultural
attitudes is the major reason wolf recov-
ery has struggled in the U.S., despite
an abundance of available land. Mean-
while, Europe, one of the most indus-
trialized landscapes on earth, has wel-
comed the return of wolves even to the
fringes of its largest cities — along with
brown bears, lynx, bison, and other spe-
cies. The surprisingly rapid recovery of
such species in Europe has led to a call,
as a recent commentary in the journal
Conservation Letters put it, for rewild-
ing to become “a primary component”
of long-term biodiversity conservation
on degraded landscapes elsewhere —
even perhaps everywhere.
In the face of “annihilation” and “Ar-
mageddon,” emphasis on tending the
margins of our lives can seem, yes, mar-
ginal. “If the focus is on degraded land-
scapes – roadside edges, powerline
rights of way – you can find examples
where these habitats are important to
particular species,” says Josh Tewks-
bury, a conservation biologist at the
University of Colorado, Boulder. “But it
would be hard to find any evidence that
it’s going to make a whit of difference to
the big problem. It’s not going to solve
95 percent of the problem.” One danger is these
landscapes may be-
come places where
excess individuals
from undisturbed
habitat can survive
but not increase.
Then, as a second thought, he added,
“It could be the 95 percent solution for
people and biodiversity,” in the sense
that routinely seeing birds in a city park,
or a fox running across a field, can have
But caution about the potential of our
cities and suburbs as wildlife habitat is
probably still a good idea. One danger
is that these landscapes may become
“ecological sinks” — that is, places
where excess individuals from undis-
turbed habitat can survive, but not ul-
timately increase. Having straw-headed
bulbuls in central Singapore does not,
for instance, ensure survival of the spe-
cies. Success with some more visible
species may also blind us to broader
but less obvious declines in other spe-
cies. European rewilding, for instance,
has not been rewilding for its insect
population.
Finally, we know almost nothing about
what ecologist Meredith Holgerson at
Portland State University calls “these
cryptic changes happening” as humans
occupy and alter a landscape. For her
doctoral research at Yale University, she
looked at the effects of suburbanization
on wood frogs in 18 ponds in the pros-
perous Connecticut suburb of Madison.
The area around the ponds had devel-
oped largely with two-acre zoning, al-
lowing for survival of “pretty good red
maple swamps and vernal ponds,” says
David Skelly, a professor of ecology at
the Yale School of Forestry & Environ-
mental Studies who oversaw the re-
search. But chemical analysis of the
ponds demonstrated that, along with
other changes, the wood frog larvae
were getting as much as 70 percent of
their nutrients from materials leaching
out of septic systems. “It suggests,”
says Holgerson, “that tadpoles and
other pond organisms are made up of
human waste.”
The consequences of that remain un-
known. But it also suggests that we
may change the entire nutrient flow of
an ecosystem, cause eutrophication, or
introduce hormone-disrupting drugs or
other chemicals in our waste — and still