More species are moving closer to extinction each year, with one fifth of the world's vertebrates under threat, but this would be even worse without conservation activities, according to a large-scale study published in the journal Science and launched today at the global biodiversity conference in Nagoya, Japan.
The black-footed ferret, Mustela nigripes, in the United States was extinct in the wild but has been reintroduced. © Wendy Shattil and Bob Rozinski
An international team of 3,000 scientists, including David Gower and Mark Wilkinson at the Natural History Museum, studied 25,000 of the world’s endangered vertebrates.
The researchers looked at species categorised as Vulnerable, Endangered and Critically Endangered on the International Union for Conservation of Nature (IUCN) Red List, the widely accepted standard for assessing species’ global risk of extinction.
They investigated how a species’ status changed over time and found that more than 50 species of birds, mammals and amphibians moved one category closer to extinction each year.
This rate of deterioration would have been 20% more in the absence of conservation activities. But these actions are outweighed by the scale of threats causing biodiversity loss, such as agricultural expansion, logging, over-exploitation, and invasive alien species.
Out of 928 cases where the status of a species changed enough to move it to a new Red List category, 68 (7%) improved in status. 64 of these were due to conservation efforts.
The Przewalski's horse, Equus ferus, was extinct in the wild and then reintroduced back to its Mongolian habitat © David Blank
Conservation prevented the equivalent of 39 species of birds (between 1998 and 2008) and 29 mammals (between 1996 and 2008) from moving one category closer to extinction.
In fact 3 species that were in the category Extinct in the Wild have since been reintroduced back to nature: the California condor, the black-footed ferret in the United States, and the Przewalski’s horse in Mongolia.
‘This is clear evidence for why we absolutely must emerge from Nagoya with a strategic plan of action to direct our efforts for biodiversity in the coming decade,’ says Julia Marton-Lefèvre, Director General of IUCN.
Officials from 193 countries are attending the last week of the 10th Meeting of the Conference of the Parties to the Convention on Biological Diversity (COP10) to discuss how to better protect nature.
The study revealed that conservation efforts have been particularly successful at combating invasive alien species on islands.
For example captive breeding, reintroduction and control of introduced animals like cats and rats have helped species such as the Seychelles magpie-robin make a comeback from less than 15 birds in 1965 to 180 in 2006.
On Mauritius, the status of 6 bird species has improved, including the Mauritius kestrel whose population has increased from just 4 birds in 1974 to nearly 1,000.
Mallorcan midwife toad. 41% of amphibian species are threatened and in the IUCN Red List. © Dr Richard A Griffiths
The research figures underestimate the impact of conservation activities, the team says. For example, as the black stilt bird remained in the Critically Endangered category it would not have been highlighted in the study. But this species would have gone extinct without predator control and its reintroduction.
Also, 9% of mammals, birds and amphibians classified as Threatened or Near Threatened have stable or increasing populations largely due to conservation efforts, but more time is needed for this to translate into an improved category status.
Museum amphibian expert David Gower comments, ‘This study demonstrates that conservation can have a life saving impact on endangered species but also makes quite clear how much more needs to be done.’
Amphibians are in an especially bad situation. 41% of amphibian species are threatened. Their high risk is increasingly blamed on the deadly infectious chytrid fungus disease, and conservation attention given to amphibians is low. Of the 68 cases in the study that had their status improved, only 4 were amphibians.
The team’s calculations found that between 1980 and 2004 the equivalent of 662 amphibian species moved one Red List category closer to extinction.
However, international efforts are starting to take effect. For example a captive breeding programme is due to reintroduce the Kihansi spray toad back into the wild in Tanzania, after its waterfall habitat was drastically changed in 2000.
The study highlights Southeast Asia as the area of the world that has had the most dramatic recent losses. These were largely driven by the planting of export crops like oil palm and commercial hardwood timber, agriculture conversion to rice paddies, and unsustainable hunting.
16% of the species studied have become extinct including 2 birds, the kamao from Hawaii and alaotra grebe from Madagascar, and at least 9 amphibians between 1980 and 2000 but possibly 95 more.
During the reporting period between 1996 and 2008, no mammals were listed as extinct. However, the Yangtze River dolphin became functionally extinct in 2006 when researchers were unable to find any living dolphins. The team says that if this is confirmed, it would be the first large vertebrate species extinction since the Caribbean monk seal in the 1950s.
The reasons for the dolphin’s extinction are cited as incidental capture in fisheries, interaction with river traffic, pollution, and environmental degradation.
Fisheries have had a worse effect on marine birds than marine mammals, with the population of 10 bird species deteriorating and none improving. Slow-breeding albatrosses and petrels have suffered declines as a consequence of increasing incidental by-catch from growth of commercial fisheries, particularly long-line and trawling. Some legislative tools have recently been put in place and may yet bring results.
The team also looked at some invertebrates and plants and found that the level of threat was 32% for freshwater crayfish, 33% for reef-building corals and a huge 63% for cycads, the most ancient group of seed plants alive today.
Museum amphibian expert Mark Wilkinson comments on species still to be discovered. ‘For many components of the world's biodiversity we are still in a phase of discovery, describing previously unknown species and obtaining information on their distribution and abundance.
‘Without such basic taxonomic and ecological work, which is the core business of Museum science, there can be no understanding of the conservation status of these most poorly known (and unknown) species.’
This study shows that despite the failure of global targets to reduce biodiversity loss by 2010, conservation efforts have not been in vain.
However, the team warns that the erosion of biodiversity has reached such dangerous levels that we cannot afford to fail again. They say ambitious targets are needed for 2020, and to meet them will require urgent and concerted action on a greatly expanded scale.