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Climate Threatens Species at Every Altitude
2011-01-21 17:32:55.983 GMT
By ELISABETH ROSENTHAL
(New York Times) -- KINANGOP, Kenya — Simon Joakim Kiiru
remembers a time not long ago when familiar birdsongs filled the
air here and life was correlated with bird sightings. His lush,
well-tended homestead is in the highlands next to the Aberdare
National Park, one of the premier birding destinations in the
When the hornbill arrived, Mr. Kiiru recalled, the rains
were near, meaning that it was time to plant. When a buzzard
showed a man his chest, it meant a visitor was imminent. When an
owl called at night, it foretold a death.
"There used to be myths because these are our giants," said
Mr. Kiiru, 58. "But so many today are gone."
Over the past two decades, an increasing number of settlers
who have moved here to farm have impinged on bird habitats and
reduced bird populations by cutting down forests and turning
grasslands into fields. Now the early effects of global warming
and other climate changes have helped send the populations of
many local mountain species into a steep downward spiral, from
which many experts say they will never recover.
Over the next 100 years, many scientists predict, 20 percent
to 30 percent of species could be lost if the temperature rises
3.6 degrees to 5.4 degrees Fahrenheit. If the most extreme
warming predictions are realized, the loss could be over 50
percent, according to the United Nations climate change panel.
Polar bears have become the icons of this climate threat.
But scientists say that tens of thousands of smaller species that
live in the tropics or on or near mountaintops are equally, if
not more, vulnerable. These species, in habitats from the high
plateaus of Africa to the jungles of Australia to the Sierra
Nevada in the United States, are already experiencing climate
pressures, and will be the bulk of the animals that disappear.
In response to warming, animals classically move to cooler
ground, relocating either higher up in altitude or farther toward
the poles. But in the tropics, animals have to move hundreds of
miles north or south to find a different niche. Mountain species
face even starker limitations: As they climb upward they find
themselves competing for less and less space on the conical
peaks, where they run into uninhabitable rocks or a lack of their
usual foods — or have nowhere farther to go.
"It's a really simple story that at some point you can't go
further north or higher up, so there's no doubt that species will
go extinct," said Walter Jetz, professor of ecology and
evolutionary biology at Yale, whose research last year predicted
that a third of the 1,000 mountain birds he studied, or 300
species, would be threatened because warming temperatures would
decimate their habitats.
Birds are good barometers of biodiversity because amateur
birdwatchers keep such extensive records of their sightings. But
other animals are similarly affected.
Two years ago, scientists blamed a warming climate for the
disappearance of the white lemuroid possum, a niche mountain
dweller in Australia that prefers cool weather, and that was cute
enough to be the object of nature tours. Many scientists,
suspecting that the furry animal had died off during a period of
unusually extreme heat, labeled the disappearance the first
climate-related animal extinction.
Since then, biologists have found a few surviving animals,
but the species remains "intensely vulnerable," said William F.
Laurance, distinguished research professor at James Cook
University in Australia, who said that in the future heat waves
would probably be the "death knell" for a number of cold-adapted
For countries and communities, the issue means more than
just the loss of pleasing variety. Mr. Kiiru regrets the vastly
diminished populations of the mythic birds of Kikuyu tribal
culture, like buzzards, owls and hawks. But also, the loss of
bird species means that some plants have no way to pollinate and
die off, too. And that means it is hard for Mr. Kiiru to tend
bees, his major source of income.
Current methods for identifying and protecting threatened
species — like the so-called red list criteria of the
International Union for Conservation of Nature, a conservation
gold standard — do not yet adequately factor in the impact of
probable climate shifts, and the science is still evolving, many
Some species that scientists say are at most risk in a
warming climate are already considered threatened or endangered,
like the Sharpe's longclaw and the Aberdare cisticola in Kenya.
The cisticola, which lives only at altitudes above 7,500 feet, is
considered endangered by the international union, and research
predicts that climate change will reduce its already depleted
habitat by a further 80 percent by 2100.
Other Kenyan birds that are at risk from climate warming,
like the tufted, brightly colored Hartlaub's turaco, are not yet
on watch lists, even though their numbers are severely reduced
here. A rapid change of climate can quickly eliminate species
that inhabit a narrow niche.
On a recent afternoon, Dominic Kimani, a research
ornithologist at the National Museums of Kenya, combed a pasture
on the Kinangop Plateau for 20 minutes before finding a single
longclaw. "These used to be everywhere when I was growing up," he
He added: "But it's hard to get anyone to pay attention;
they are just little brown birds. I know they're important for
grazing animals because they keep the grasses short. But it's not
dramatic, like you're losing an elephant."
As the climate shifts, mountain animals on all continents
will face similar problems. Scientists at the University of
California at Berkeley recently documented that in Yosemite
National Park, where there is a century-old animal survey for
comparison, half the mountain species had moved their habitats up
by an average of 550 yards to find cooler ground. Elsewhere in
the United States, the pika, the alpine chipmunk and the San
Bernardino flying squirrel have all been moving upslope in a
pattern tightly linked to rising temperatures. They are now
considered at serious risk of disappearing, said Shaye Wolf,
climate science director of the Center for Biological Diversity
in San Francisco, which in 2010 applied to protect a number of
American mountain species under the United States' Endangered
Last year, new research in the journal Ecological
Applications and elsewhere showed that the pika, a thick-furred,
rabbitlike animal that takes refuge from the sun in piles of
stones, was moving upslope at about 160 yards a decade and that
in the past decade it had experienced a fivefold rise in local
extinctions, the term used when a local population forever
On the Kinangop Plateau in Kenya, Mr. Kimani exults when he
finds a Hartlaub's turaco, once a common sight, near Njabini
town, in a stand of remaining of old growth forest, after
engaging local teenagers to help locate the bird. The turaco
could lose more than 60 percent of its already limited habitat if
current predictions about global warming are accurate, according
to Dr. Jetz.
"Even substantial movement wouldn't help them out," he said.
"They would have to move to the Alps or Asian mountains to find
their mountain climate niche in the future."
Copyright 2011 The New York Times Company
-0- Jan/21/2011 17:35 GMT