THE world鈥檚 birds are in crisis. Despite concerted conservation attempts, more than 1000 species face extinction caused by habitat loss, predation by alien species and climate change, and the status of most is not improving.
This sobering analysis comes from a 70-page report presented to more than 300 delegates at the world conference of BirdLife International under way in Durban, South Africa, this week. The report, State of the World鈥檚 Birds 2004, compiled by BirdLife鈥檚 secretariat in Cambridge, UK, shows scant evidence of any progress towards slowing the loss of the planet鈥檚 biodiversity before 2010, the target set by governments at the World Summit at Johannesburg in 2002.
By the latest estimate, 1211 out of around 10,000 known bird species are facing extinction. This figure has crept inexorably upwards in the past 10 to 15 years; it is only in this period that criteria by which the risk of extinction is assessed have been both rigorous and internationally agreed. 鈥淲hat makes the assessment especially telling is that, for birds, visible and well-watched, it is possible to track the well-being (or otherwise) of virtually every species,鈥� says Alison Stattersfield, who is responsible for monitoring threatened species for BirdLife.
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In the past four years, the status of species threatened with extinction has worsened as populations have dwindled and habitats have been destroyed. The deterioration is evident roughly equally in all habitats and among all bird groups, although seabirds affected by commercial long-line fisheries have fared especially badly. For every threatened species whose status has improved, four have remained in the doldrums and another four find themselves in an even worse state than before. Two species, Spix鈥檚 macaw in Brazil and the Hawaiian crow, have vanished from the wild.
There are many causes for the decline. One is the growth of the human population, leading to the destruction of natural habitat and its conversion to ever more intensive agriculture. Indonesia, where three-quarters of the logging now taking place is illegal, lost 40 per cent of its forest between 1950 and 2000, and the rate of loss is increasing. Alien species, such as rats and domestic cats, have caused the extinction of at least 65 bird species since 1500.
And the effects of global warming have yet to be felt. In Australia, as many as a dozen montane species may go extinct within a century as their habitat disappears with climate change.
More subtle forces are also at work. Many endangered birds have small geographic ranges: for example, one rare hummingbird, the black-breasted puffleg, is found only in a few forest patches close to Quito in Ecuador. It turns out that hotspots for birds, most of which are in the developing world, often have especially high human population densities. 鈥淲hy this association should exist for birds and indeed also for mammals and flowering plants is a puzzle,鈥� says Andrew Balmford, a conservation biologist at the University of Cambridge. This association undoubtedly increases the potential for conflict between human development and conservation.
Since 2000, two-thirds of the world鈥檚 threatened bird species have received some conservation attention, Stattersfield notes. 鈥淥ften this has been in the form of surveys and baseline studies.鈥� Though this doesn鈥檛 itself put more eggs in nests, she says, 鈥渢hey are a necessary basis for effective conservation actions that will increase populations鈥�.
While the BirdLife study indicates that under 25 per cent of the threatened species have benefited to some extent, only a paltry 4 per cent gained 鈥渟ignificant benefit鈥� from the conservation actions so far (see Graph).
