Global patterns of net change in overall extinction risk across birds, mammals and amphibians mapped as average number of genuine Red List category changes per cell per year. Purple shades correspond to net deterioration (i.e., net increase in extinction risk) in that cell, green to net improvement (i.e., decrease in extinction risk), and white to no change. (Science/AAAS)At least one-fifth of the world's mammals, birds, reptiles, amphibians and fish are threatened with extinction due to human activity, a new study concludes.

"More worrying is that when we look at the trends … we find that there are more species moving toward extinction or even becoming extinct than there are species that are recovering," Craig Hilton-Taylor of the International Union for the Conservation of Nature, one of the lead authors of the study published in Science Express, said Tuesday during a telephone news conference.

The study found about 50 species move one category closer to extinction each year on the IUCN Red List. The polar bear has moved from "least concern" to "vulnerable." (U.S. Fish and Wildlife Service)Ana Rodrigues, another of the paper's 174 co-authors, said that while the trends might be disheartening, the research also showed some hope.

"What our results show is that conservation efforts are not wasted," said Rodrigues, a researcher at the Centre d'Ecologie Fonctionelle et Evolutive in Montpellier, France. "They are making a noticeable difference."

The rate of deterioration would be at least 20 per cent worse without conservation efforts, the report said.

Rodrigues highlighted the case of the black-footed ferret, which is coming back in the U.S. midwest after being reintroduced to the wild. Nick Dulvy, Canada research chair in marine biodiversity and conservation at Simon Fraser University, noted that similarly the blue whale and the humpback whale have been recovering since a whaling ban in 1966.

The study, billed as "the most comprehensive assessment of the world's vertebrates" by the IUCN, was released as world leaders met in Nagoya, Japan, for the United Nations biodiversity summit in an effort to reach an international agreement on how to halt the worldwide decline.

Stuart Butchart, global research co-ordinator for Birdlife International, said biodiversity loss should be a concern worldwide because living organisms help provide clean drinking water, pollination, pest control, flood control and other "ecosystem services" worth $33 trillion a year.

He urged world leaders to step up their conservation efforts.

"Our results should be a timely wakeup call to governments in Nagoya. Biodiversity is in a desperate state," he said "But we can turn things around. We just need greater political will and resources."

The study was based on the IUCN Red List, which describes 25,780 vertebrates, including their distribution, population trends and how threatened they are, based on a list of nine categories from "least concern" to "extinct." The study found about 50 species move one category closer to extinction each year, due largely to human activities such as agriculture, logging, urban development, hunting and fishing.

Sharks, amphibians most threatened

Things are particularly dire for sharks and amphibians, for which one in three species are threatened, the tall found.

A third of amphibians and a fifth of vertebrates overall are threatened with extinction, and more species are moving closer to extinction than recovering. This reed frog was thought to be extinct, but was recently rediscovered in Congo. (Jos Keilgast/Natural History Museum of Denmark/Conservation International)Most threatened species live in tropical regions, and Southeast Asia has experienced the most dramatic recent species losses, blamed largely on habitat loss to logging and crops like oil palm and rice, as well as unsustainable hunting.

However, Rodrigues said that even though Canada has a low population density, a lot of its species are widespread and it has the capacity to do lots of conservation, it is home to a number of threatened species, including the nearly extinct Vancouver Island marmot.

"This species alone is driving Canada's score low," she added.

Dulvy said Canada has done a good job of protecting land-based animals through the Species at Risk Act but needs to show more leadership in the protection of marine species, which aren't covered by the act.

Butchart said countries like Canada also need to take responsibility for the biodiversity loss beyond their own borders.

"In western countries, levels of consumption are so high that's it's our demand that is causing the deforestation, the intensifying of agriculture, the production of commodities … that are leading to the land-use change and the threats to biodiversity in the tropics, which is where most species are found," he said.

And when it comes to the biodiversity talks in Nagoya, Canada and the European Union are both blocking a binding treaty against "biopiracy" that would ensure developing countries can profit from the genes of their native plant and animals species.

"If that protocol doesn't get agreed, it looks like it's going to be very limited progress on all the other topics," he said. "Canada is playing a particularly obstructive role in those negotiations, which could be disastrous for biodiversity worldwide."