[TN-Bird] Empty Skies: World's Birds At Risk
- From: Beau Peyton <bpeyton@xxxxxxxxxxxxxxx>
- To: TOS <tn-bird@xxxxxxxxxxxxx>
- Date: Wed, 07 Dec 2005 12:47:29 -0600
Interesting article from Lester Brown's group worth passing on...
Beau Peyton
Germantown, TN
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EMPTY SKIES: WORLD’S BIRDS AT RISK
http://www.earth-policy.org/Updates/2005/Update50.htm
Janet Larsen
Even before canaries were brought into coal mines to alert miners to the
presence of poisonous gas, birds were giving us early warning calls
signaling the earth’s deteriorating environmental health. Worldwide, some
1,212 of 9,775 bird species—one out of every eight—are threatened with
extinction. Destruction and degradation of habitat is the number one
danger, threatening 87 percent of these vulnerable birds.
As an ever-expanding human population has altered natural places around
the globe—wetlands, grasslands, and forests—bird numbers have fallen.
Global bird populations have shrunk by up to 25 percent since
pre-agricultural times, largely because of conversion of habitat to farms.
Over the past 300 years, farmland has expanded from 6 percent of the
earth’s surface to nearly a third.
Today three quarters of threatened bird species depend on forests as their
principal habitat; each year, however, some 13 million hectares of forests
are destroyed, an area the size of Greece. Nearly half the forests lost
are relatively undisturbed primary forests that are home to a number of
sensitive birds and other creatures.
The sharpest declines in avian populations in recent years have come in
Asia, particularly in Borneo and Sumatra, where lowland moist tropical
forests are disappearing at an astonishing rate. By 2000, some 40 percent
of Indonesia’s forests had been cleared. Now three out of every four bird
species that depend on Sumatra’s lowland forest are on the verge of
extinction. In addition to the loss of forests due to logging for lumber,
the increasing demand for palm oil—recently prized as a biofuel—has raised
pressure to convert natural forests to palm plantations. Without a rapid
reversal of deforestation trends, all the lowland forest could be lost
within a decade. Overall, some 118 of Indonesia’s bird species, including
several endemic parrots and cockatoos, are threatened with extinction—the
highest number of any country.
Close behind in numbers is Brazil, where 115 bird species are threatened.
Both the Amazonian rainforest and the savannah-like cerrado are being
cleared for ranches and farms, most recently for large-scale soybean
production for feed, food, and fuel. In addition, Brazil’s Atlantic
rainforest has shrunk by 90 percent, squeezed by growing cities and farms.
This fragmented forest is home to some 950 kinds of birds, 55 of which are
endemic and threatened.
Since 1500, 150 species of birds are believed to have disappeared
entirely. Some 50 of these extinctions were the result of overhunting.
Hunting brought the demise of North America’s passenger pigeon, once the
most numerous bird on earth, within a human lifetime. Direct exploitation,
including hunting for food and capture for the pet trade, is the second
greatest danger after habitat loss, affecting nearly a third of threatened
bird species today. Fifty-two of the world’s 388 parrot species are at
risk from overexploitation. (See data at
www.earthpolicy.org/Updates/2005/Update50_data.htm.)
The intentional or accidental introduction of non-native species is the
next greatest danger, affecting 28 percent of the world’s threatened
birds. As people travel to all parts of the globe, so too do the pests and
pets that prey on, out-compete, or alter the habitat of native wildlife.
Introduced rats and cats alone have led to the extinction of 50 bird
species. In the Hawaiian Islands, introduced predators and diseases have
compounded problems of habitat loss and knocked out more than half of the
100-plus endemic bird groups. Possums, rats, and other mammals brought
into New Zealand in the past 200 years have ravaged the once-abundant
diversity of large birds that had evolved over 80 million years with no
natural predators.
Pollution poses an additional risk, affecting 12 percent of the threatened
bird species. In India, Gyps vulture populations have plummeted by 95
percent in less than a decade, many poisoned by medicine used to treat the
livestock they feed on. Populations of common Western European farmland
birds dropped by 57 percent between 1980 and 2003, with much of the
decline attributed to the intensification of agriculture. In addition to
direct poisoning from fertilizer and pesticide applications, runoff of
chemicals contaminates the wetlands that migrating waterfowl rely on.
Persistent organic pollutants, such as DDT residues, dioxins, and
polychlorinated biphenyls, accumulate in the food chain and can lead to
deformities, reproductive failure, and disease in birds.
Climate change is a relatively new threat to birds and other wildlife.
Worldwide, a third of plant and animal species could become extinct by
2050 as a result of climate change. Over the last three decades, global
temperatures have risen by 0.6 degrees Celsius (1 degree Fahrenheit),
bringing changes to the migration, breeding, and habitat ranges of some
birds. For example, as spring has come earlier in the Netherlands, so too
has the emergence of the caterpillars that great tit birds need to feed to
their nestlings. Unfortunately, the birds’ egg-laying date has not
shifted, putting the hatching of the chicks out of sync with their food
supply.
Birds that spend all or part of their lives at the earth’s poles are
particularly vulnerable to rising temperatures. The migratory waterbirds
in the Arctic will lose out as warming alters this vulnerable ecosystem.
In the Southern Hemisphere, where 10 of the world’s 17 penguin species
already are threatened, conditions will not improve as global temperatures
increase by a projected 1.4–5.8 degrees Celsius (2.5–10.4 degrees
Fahrenheit) during this century.
In addition to these looming threats, 7 percent of threatened bird species
are at risk from incidental mortality. A rapid decline in seabird
populations over the last 15 years corresponds with the growth in
commercial longline fisheries. Each year these operations kill some
300,000 seabirds that are tempted by bait and then ensnared. All 21
species of albatross are now threatened or near-threatened because of
run-ins with the fishing industry. Birds also fall prey to industrial
development, which endangers more than half of the threatened birds in
eight Latin American and Caribbean countries. In Europe, Central Asia, and
Africa, electrocution on power lines has caused the mass mortality of
raptors. And hundreds of millions of birds in the United States die each
year from collision with windows, the number one cause of U.S. avian
mortality.
If birds disappear, so do the economically valuable services they provide.
Birds pollinate flowers, disperse seeds, and help to eliminate rodents,
insects, weed seeds, and other pests. Scavenger species recycle nutrients
and clean up dead and decaying animals that might otherwise be sources of
disease.
Preventing the decline and extinction of additional bird populations
depends largely on protecting the world’s remaining wild spaces and
preserving the health of our natural and altered ecosystems. For species
that are critically endangered, more-intensive management may be needed if
population numbers are to return to a viable level. This may include
captive breeding and re-introduction, and the active removal of invasive
predators to the extent possible. To prevent the spread of avian disease,
more stringent biosecurity is needed to limit contact between infected
domestic flocks and wild birds. Diverting birds away from artificial
structures—buildings, towers, and turbines—and siting new construction
outside of migratory paths also could prevent avian fatalities.
Reports this past spring that the ivory-billed woodpecker, long thought to
be extinct, is still with us thrilled birdwatchers and others, but this
sort of second chance seldom occurs in nature. Even with continued habitat
protection, once wildlife populations drop dramatically, a rebound is far
from guaranteed. And without stabilizing climate and human numbers,
putting fences around all the parks in the world will not be enough to
protect threatened species.
# # #
Additional data and information sources at www.earthpolicy.org or contact
jlarsen(at)earthpolicy.org
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