- By the end of the century one in 10 species of birds
in the world will be extinct and a further 15 per cent will be on the brink
of extinction according to one of the largest studies of avian biodiversity.
- The dire state of birds is documented in an American
university study which shows their decline will accelerate rapidly in a
world of habitat loss, disease, climate change and over-exploitation.
- It is estimated that just over 1 per cent of bird species
have become extinct in the past 500 years but this is set to increase tenfold
over the next 100 years, according to a study led by Cagan Sekercioglu
of Stanford University in California.
- The researchers found that the loss of birds will not
only have an impact on other wildlife but could also increase the risk
of epidemic diseases hitting the human population.
- They cite the recent decline of three species of Indian
vulture, caused by the widespread use of a veterinary drug by local cattle
farmers. The decline led to an explosion in the population of feral dogs
feeding off dead cows, leading to 30,000 cases of human rabies a year.
- "Our projections indicate that, by 2100, up to 14
per cent of all bird species may be extinct and that as many as one out
of four may be functionally extinct, that is critically endangered or extinct
in the wild," Dr Sekercioglu said. "Even though only 1.3 per
cent of bird species have gone extinct since 1500, the global number of
individual birds is estimated to have experienced a 20 to 25 per cent reduction
during the same period," he said.
- "Given the momentum of climate change, widespread
habitat loss and increasing numbers of invasive species, avian declines
and extinctions are predicted to continue unabated in the near future,"
- The study involved analysis of all 9,787 species of birds
alive today, and of the 129 species that have gone extinct recently, to
produce one of the most comprehensive databases ever compiled into the
state of one class of animals.
- Using a computer forecast based on current rates of decline,
the researchers found overall that just over one in four bird species is
currently prone to extinction and 6.5 per cent are "functionally extinct",
meaning they no longer play a meaningful role in the local ecology.
- A quarter of fruit-eating birds and omnivorous species
are in danger of becoming extinct, along with a third of herbivorous, fish-eating
and scavenging species.
- In the worst-case scenario put forward in the study published
today in the journal Proceedings of the National Academy of Sciences, the
researchers predict that threatened bird species will increase by 1 per
cent each decade.
- "These assumptions are conservative, since it is
estimated that every year natural habitats and dependent vertebrate populations
decrease by an average of 1.1 per cent," says the study.
- Gretchen Daily, a member of the research team, said it
may be difficult to imagine how the loss of a particular species of bird
can cause an outbreak of human disease. "Yet consider the case of
the passenger pigeon. Its loss is thought to have made Lyme's disease the
huge problem it is today.
- "When passenger pigeons were abundant and they used
to occur in unimaginably large flocks of hundreds of millions of birds,
the acorns on which they specialised would have been too scarce to support
the large populations of deer mice, the main reservoir of Lyme's disease,
that thrive on them today," said Professor Daily.
- © 2004 Independent Digital (UK) Ltd