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The march to extinction accelerates

A fifth of the world’s vertebrate species (i.e. mammals, birds, reptiles, amphibians, and fish) are threatened with extinction, according to a massive new study by the International Union for the Conservation of Nature (IUCN); and the situation is worsening for the world’s wildlife: on average 52 species of mammals, birds, and amphibians move one category closer to extinction every year (the IUCN Red List categorizes species as Least Concern, Near Threatened, Vulnerable, Endangered, Critically Endangered, Extinct in the Wild, and then Extinct). However, the news isn’t all bad. The study found that conservation action does work: in the first analysis of its kind, researchers found that the global biodiversity decline would have been 18% worse if not for conservation attention, “nonetheless,” the authors—174 scientists from 38 countries—write, “current conservation efforts remain insufficient to offset the main drivers of biodiversity loss.” According to the study, these drivers include agricultural expansion, logging, over-exploitation of species, and invasive species.

“The ‘backbone’ of biodiversity is being eroded,” said renowned ecologist and writer Professor Edward O. Wilson from Harvard University. “One small step up the Red List is one giant leap forward towards extinction. This is just a small window on the global losses currently taking place.”

The study is being launched today at the Convention on Biological Diversity (CBD) in Nagoya, Japan. International leaders are meeting to come up with an agreement to save biodiversity after failing to meet the goal of stemming biodiversity loss by this year.

The Hardest Hit

According to the study, the worst place to be an animal in the world is the tropics, with particular emphasis on the Southeast Asian tropics. Southeast Asia sports the world’s highest concentration of threatened species. Deforestation has exploded in many countries in Southeast Asia over the past few decades from unsustainable logging and industrial plantations, such as palm oil, rice, and pulp and paper. In addition, hunting for food and traditional medicines has decimated a large number of animals in the region.

Global patterns of threat, for land (terrestrial and freshwater, in brown) and marine (in blue) vertebrates, based on the number of globally threatened species in total. Darker areas have higher concentrations of threatened species. Click to enlarge.

Even Southeast Asia’s most iconic species—rhinos, orangutans, tigers, and elephants—face extirpation and in some cases total extinction. The Javan rhinoceros is down to some 40-60 individuals, none of which are in captivity.

But as far as type of species goes, nothing is worse than being a frog: according to the study 41% of the world’s amphibians are threatened with extinction. In contrast, 33% of cartilaginous fishes, 25% of mammals, 22% of reptiles, 15% of bony fishes, and 13% of birds are threatened.

Highly-sensitive to environmental changes amphibians face a barrage of threats, including habitat loss, pollution, climate change, agricultural chemicals, and overconsumption for food and the pet trade. However, the largest threat to amphibians is known as the ‘amphibian plague’: chytridiomycosis, a fungal disease, has decimated amphibian populations even in pristine environments. Recent studies have shown that frog species never known to science have already been lost. At least 120 amphibians have vanished entirely in the past three decades, making this group a poster child for the extinction crisis.

But of all the world’s species—vertebrates, plants, fungi, insects, etc.—vertebrates make up just 3% of the total. The study also reported on a number of non-vertebrate species types—not included in the overall analysis—finding, for example, that 14% of seagrasses, 32% of freshwater crayfish, and 33% of coral reef species are threatened with extinction. An earlier study, looking at a representative sample of plants, found that 22% of the world’s plant species are threatened with extinction.

One of the most threatened groups of species on Earth is the cycads, an ancient group of plants: 63% percent of cycads face extinction.

Conservation Works

On the bright side, the study also found that conservation action—such as protected areas and legislation—has mitigated some of the loses in species and abundance. Analyzing species that have seen improvement from conservation attention, the study found that the biodiversity crisis would be 18 percent worse today for birds and mammals if conservation action hadn’t occurred.

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. The uniform pattern of improvement at sea is driven by improvements of migratory marine mammals with cosmopolitan distributions (e.g., humpback whale). Click to enlarge.

“History has shown us that conservation can achieve the impossible, as anyone who knows the story of the White Rhinoceros in southern Africa knows”, remarked Dr Simon Stuart, Chair of IUCN’s Species Survival Commission and an author on the study. “But this is the first time we can demonstrate the aggregated positive impact of these successes on the state of the environment.”

In 7% of cases species that moved categories in the assessment moved to a safer category rather than a worst. While this is sad reflection of the state of biodiversity worldwide, the researchers found that nearly all of those species that showed improvement did so because of targeted conservation action. However, according to the authors, even this assessment doesn’t measure the fill importance of conservation.

“These results grossly underestimate the impact of conservation, because they do not account for species that either would have deteriorated further in the absence of conservation actions, or improved numerically though not enough to change [their category],” the authors write.

In terms of effectiveness, the study found that conservationists were most adept at combating invasive species, rather than slowing deforestation or regulating hunting.

Three extreme cases of conservation-in-action included reintroducing animals back into their ecosystems after they have gone extinct in the wild: the California Condor, (Gymnogyps californianus), the Black-footed Ferret, (Mustela nigripes), and Przewalski’s Horse (Equus ferus). Such species give hope in particular to amphibians, some of whom survive now only in zoos. Currently one such frog, the Kihansi spray toad, is being reintroduced after going extinct in Tanzania.

“The stark reality of accelerating species losses can lead to a feeling of hopelessness,” says Mindell, Dean of Science at the California Academy of Sciences. “However, the IUCN data analyzed in this assessment show that concerted efforts by biologists and conservationists can make a positive difference in slowing rates of endangerment. Hopefully, these findings will bolster existing efforts at conservation—and spawn new initiatives as well.”

Yet, despite decades of conservation attention and funding, many notable species are still dropping in population: for example, according to the IUCN the tiger (panthera tigris) is still classified as Endangered and its population still decreasing. Although its likely tigers would be far worse off, maybe even extinct, if not for ongoing conservation measures.

In addition, most species in the world are not like tigers. They do not receive targeted conservation funds or attention, even when they are on the edge of extinction. For example, the Vietnam leaf-nosed bat (Paracoelops megalotis) was listed as Critically Endangered for 12 years before it was moved to Data Deficient. It remains wholly unstudied by researchers and may already be extinct. But no one knows.

“The current level of [conservation] action is outweighed by the magnitude of threat, and conservation responses will need to be substantially scaled up to combat the extinction crisis,” the authors conclude. “Even with recoveries, many species remain conservation-dependent, requiring sustained, long-term investment […] The 2010 [CBD] biodiversity target may not have been met, but conservation efforts have not been a failure. The challenge is to remedy the current shortfall in conservation action to halt attrition of global biodiversity.”

Total species assessed by the IUCN Red List = 55,926 (Scientists have identified almost 2 million species on Earth, though researchers estimate that there are probably 10-50 million species in total.)

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