If a creature has a spine and walks, flies, swims, or crawls, it may be in serious trouble.
Some 20 percent of all vertebrate species on Earth are threatened by extinction, according to a newly published survey – a study the research team involved says is the most exhaustive to date on biodiversity among vertebrates.
The losses are due largely to human encroachment on habitat, over-fishing and over-hunting, as well as the arrival of invasive species in habitats whose natural inhabitants have no defenses against the invaders, the study says.
But within an admittedly bleak global picture, the researchers add, conservation efforts have halted the decline in some species and brought others a significant step closer to recovery.
"The bad news can be extremely disheartening," says Ana Rodrigues, a scientist with the Center for Functional and Evolutionary Ecology in Paris and one of a team of 174 scientists from 38 countries who co-authored the study.
"But our results show that conservation efforts are not wasted," she adds.
Biodiversity refers to the variety of plant and animal species in an ecosystem. Generally the greater the diversity, the more resilient the ecosystem is to disturbances, either natural or man-made.
Using an internationally recognized "red list" index that tries to capture changes in a species' population size, structure, and geographic range, among other factors, the team found that without conservation programs, biodiversity among birds and mammals would have declined an additional 18 percent over the past 30 years. The programs range from efforts to establish safe havens such as marine protected areas or wildlife reserves to campaigns to battle invasive species.
The report draws on research conducted by some 3,000 scientists worldwide. It was published Tuesday on the journal Science’s website as delegates from 194 countries were meeting in Nagoya, Japan, to try to set conservation targets for the next decade under the UN's Convention on Biological Diversity, which is scheduled to end Oct. 29.
Eight years ago, parties to the convention agreed to significantly reduce the rate of biodiversity loss by 2010. But in April, a study published online in Science showed that the rate of decline in biodiversity across a broad range of plants and animals was not slowing. Countries had failed to meet the 2010 goal.
Losses in tropics
For this latest project, the team focused on vertebrates – a group that includes animals that are most important to humans either for food or for their cultural or social significance. The group looked at 25,780 vertebrate species. They used the International Union for the Conservation of Nature's (IUCN) seven categories for a species' status – from "least concern" to "extinct."
The researchers calculate that 52 species or birds, mammals, and amphibians move one category closer to extinction each year. One in eight bird species, one in seven bony fish species, one in four mammal species, and one in four reptile species are currently threatened with extinction, says Craig Hilton-Taylor, who manages the "red list" program for the IUCN.
The biggest losses are coming in the tropics, with Southeast Asia as the region experiencing the greatest declines in vertebrate biodiversity, the study shows.
By some estimates, healthy ecosystems with robust populations of indigenous species provide services to humans that are worth $33 trillion a year globally for everything from water purification and food to pest and flood control.
Andrew Deutz, director of international relations for the Nature Conservancy, a conservation group based in Arlington, Va., says biodiversity conservation isn’t just for the rich. He cites work by economist Pavan Sukhdev showing that 45 percent of the GDP of India's poorest people relies on healthy ecosystems.
Biodiversity’s failing grade for 2010 appears to add conservation to a growing list of environmental issues where the largely harmful effects from human influence are outpacing the ability of political institutions to confront them.
Relatively quick payback
But as countries consider next steps toward stemming biodiversity's decline, some conservationists say they see hope in one key difference between preserving biodiversity and, say, dealing with global warming. Whereas well-executed conservation measures can provide a relatively quick economic payback, they say, economists and some climate scientists say dealing with global warming is more akin to buying an insurance policy. It involves accepting some level of economic sacrifice now in exchange for staving off plausible but still-uncertain effects in the future.
"We've got a pretty good case history, built up over the last decade or more, where biodiversity conservation, poverty alleviation, and local livelihood supports have gone hand in hand, we've been able to achieve win-wins," Dr. Deutz says.
Fisheries rebound where marine protected areas have been established, he notes. In Nepal, after the government clear-cut forests, it turned forest management over to locals, who nursed the affected forests back to a level where they could provide the same ecosystem services – such as slowing erosion – as the forests they replaced.
The challenge for the international community now, Deutz says, is adapting lessons from local examples so they work not just at the scale of a village of 500 people, but across an entire country.