One Creature Drives So Many Species To Extinction
of animals and plants are being driven out of existence
and scientists say that mankind
is almost always to blame
Steve Connor, Science Editor, May 21, 2002
Earth is going through its sixth and probably its most
devastating period of mass extinction with scores, and
possibly hundreds of species of animals and plants dying
out each year. But unlike the previous five extinction
waves, this time the culprit is just another lifeform,
United Nations report on the environment, to be published
tomorrow, will highlight the scale of a problem many conservationists
believe is likely to rapidly worsen over 30 years as wildlife
congregations are destroyed or invaded by a less diverse
range of species.
scientists believe the "sixth wave" of mass
extinction is between 1,000 and 10,000 times greater than
the normal "background" rate at which species
are lost naturally.
a dramatic fall in biological diversity is identified
as one of the most pressing problems facing humanity,
by the scientists who contributed to the Global Environment
Outlook-3 (Geo-3) report of the United Nations Environment
report will identify some 11,046 species of plants and
animals known to face a high risk of extinction, including
1,130 mammals - 24 per cent of the total - and 12 per
cent, or 1,183 species of birds.
activities, from habitat destruction to the introduction
of alien species from one area to another, are listed
as the main causes of this dramatic loss in biodiversity.
In the report, scientists also identify 5,611 species
of plants known to be on the verge of extinction. They
say the true figure is likely to be far higher, given
that only 4 per cent of the world's known plant species
have been properly evaluated.
Geo-3 report covers almost every aspect of environmental
degradation, from forest destruction to water pollution.
It is designed to set the framework for the world summit
on sustainable development to be held this summer in Johannesburg.
looks back on the past 30 years of environmental degradation,
since the 1972 Stockholm conference on the human environment,
to assess the likely prospects for the next 30. It is
likely to warn that many of the factors that led to the
extinction of species in recent decades continue to operate
with "ever-increasing" intensity.
threats to life on Earth are over-exploitation of natural
resources, pollution, habitat destruction, the introduction
of alien species and global climate change, say the scientists
who advised Unep.
identify the loss of habitats by human encroachment as
one of the most pervasive threats to wildlife. Habitat
loss and fragmentation of breeding grounds are behind
the precarious predicament of 89 per cent of threatened
birds, 83 per cent of threatened mammals and 91 per cent
of endangered plants, the Unep scientists say.
addition to growing poverty and climate change caused
by global warming, Unep has identified alien invasive
species as another serious threat to biodiversity, affecting
30 per cent of threatened birds and 15 per cent of threatened
black rat, which since 1800 has stowed away on ships sailing
to the remotest corners of the world, is held responsible
for the biggest slaughter of birds, especially those on
of man's hitchhikers has caused havoc to native wildlife
from Hawaii to the Seychelles and Zanzibar. The crazy
ant, so called because of its frenetic movements, killed
three million crabs in 18 months on Christmas Island alone.
host of other invasive aliens have also inflicted enormous
environmental and economic damage throughout the world.
The list includes the brown tree snake, the small Indian
mongoose, the Nile perch, the strawberry guava, the water
hyacinth, the zebra mussel and the brushtail possum.
species of animals and plants in Britain are threatened
by a similar invasion of aliens. The water vole is being
killed off by the American mink, the eggs of rare wading
birds nesting in the Outer Hebrides are being eaten by
hedgehogs introduced from the mainland, and the wetland
habitats of the Norfolk Broads suffered decades of destruction
by the coypu, a South American rodent.
McNeely, chief scientist at the International Union for
Conservation of Nature in Geneva, said the next 30 years
could be the defining moment for life on Earth. Either
we can finally recognise the problems and do something
about them, or we do not, he said.
could go either way. It could be a golden age of nature
conservation, or it could be a disaster scenario. If we
assume a doomsday scenario then we're going to live in
a greatly oversimplified world.
of the remaining species are going to be widely dispersed
and cosmopolitan. We will have lost many of the large
mammals and birds, and life in general will be more homogeneous,
with a smaller capacity to adapt to a changing environment."
the next 30 years, if the biodiversity crisis is not addressed,
it is likely that the last tiger, rhinoceros, Asian elephant,
cheetah and mountain gorilla will have been lost in the
wild, Dr McNeely added.
it is the well-known animals and plants which are at greatest
risk. The Chinese alligator is the most endangered crocodilian,
with only 150 individuals in the wild. Half of the world's
insect-eating pitcher plants are threatened and one, the
green pitcher plant, is critically endangered because
of the loss of its wetland habitat.
have identified and named about 1.5 million species but
they believe that between 5 million and 15 million species
have yet to be formally classified. It is now generally
assumed that many unnamed animals, plants and micro-organisms
are going extinct before they are even known to science.
May, an Oxford zoologist, believes present extinction
rates are likely to increase further over the next century.
He said: "This represents a sixth great wave of extinction,
fully compatible with the big five mass extinctions of
the geological past, but different in that it results
from the activities of a single other species rather than
from external environmental changes."
catalogue of extinction is in danger of going unrecorded
as fewer scientists are being trained in the field of
taxonomy, the science of systematic classification.
week, the House of Lords Select Committee on Science and
Technology warned that a shortage of taxonomists and underfunding
of the research centres for systematic biology was jeopardising
efforts to protect wildlife. How can biodiversity be protected
if no one is recording what is there? "We have a
cultural and moral obligation, as well as a pragmatic
economic need, to record and, as far as possible, conserve
the diversity of life with which we share the planet,"
the committee said.
Natural History Museum and Kew Gardens in London are two
world-reknowned centres for animal and plant taxonomy
yet the committee found that both were finding it difficult
to provide a service because of financial constraints.
"It has also placed the reference collections of
specimens comprising a wide range of biodiversity, which
are housed in these institutions, at considerable risk,"
the committee added.
Paul Henderson, director of science at the Natural History
Museum, said systematics and the description of species
was critical to the preservation of animals and plants,
and the key to economic prosperity for many of the poorer
nations in the world. He said it was at the heart of the
sustainable development theme of the forthcoming world
helped to identify the screw-worm when it invaded African
livestock from South America," Professor Henderson
said. "Without recognising it early on, it would
have wreaked havoc with enormous economic consequences,"
being able to name species will not, in itself, stop the
inexorable decline, he said. "In 30 years? We'll
still be heading for very fast rates of extinction comparable
to today simply because we're not doing anything about
it," the professor said. "I have to be a bit
gloomy on the 30-year time-scale. There's not been very
much action to justify being optimistic."